# XT and XTR brakes get squeal/power loss after sitting idle for 6-8 weeks



## rfxc (Oct 18, 2004)

What happens to shimano brake pads when my bike sits in the basement for 6-8 weeks without riding? Help me, I'm baffled.

Backstory:
In the last 2 years, my wife have had over 7 bikes in our house each with either Shimano M98x or M78x brakes on them. They either came stock on a bike, or I bled them and installed them myself. 

We'll ride a bike for couple months in the fall, brakes work great-- quiet, powerful, zero drama. put the bike in the basement for a couple months, pull it out in March to ride, and boom-- brakes squeal like crazy, less grabby, less power. Bikes are stored right side up, in various parts of my basement, leaning against a wall, etc.

This has been happening on various bikes. Various pad compounds, organic and metallic, finned and not finned. Genuine Shimano and truckerco pads.

Removing and sanding sometimes helps, but often only for a minute or two-- full power just doesn't return.

My solution is to buy cheap (truckerco) pads in bulk and replace when this happens. 

My LBS has said the same thing about their XT equipped demo/rental bikes that sit for a month plus without use. What gives?

What the heck am I missing? Please share your well thought out hypothesis.


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## rfxc (Oct 18, 2004)

I just can't buy into the notion that pads get contaminated by "absorbing moisture from the air while sitting idle" or some such thing.


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## aerius (Nov 20, 2010)

Did you notice any oil residue or any other sign of leaks or pad contamination?

One thing I can think of, at least on the M78x brakes is a slow leak on the o-ring between the two caliper halves on the banjo bolt. If the bike is ridden frequently it keeps the oil burned off so the pads don't get contaminated, but let the bike sit for long enough and the oil will get into the pads. This however doesn't explain the M98x since with one piece calipers it doesn't have that o-ring. The only other possibility is bad piston seals, but this isn't Avid here so it's very unlikely.

One possible solution would be to remove the brake pads when you put the bikes into storage, then check the calipers at the beginning of the season and clean them if needed. As an experiment, you could try leaving the pads in on one bike and then compare it against the bikes where the pads were removed. If both sets are bad, it's a pad problem, if only the set that was left on went bad, it's a leaking caliper.


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## Cleared2land (Aug 31, 2012)

*In my head, I can hear the theme to The Twilight Zone playing softly*


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## matto6 (Dec 28, 2013)

I just rode my bike with xt brakes for the first time in 2.5 months and the front brake has significantly less bite and requires more force than the rear. It also squeals sometimes. I suspect it's the phenomenon discussed above. 

What is the solution? New pads? 

Have others experienced this?


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## skinnybeans (Jun 12, 2009)

I'm having issues with my rear XT. Front works great but the back has much less power and squeals. It lever feels firm but just no stopping power so guessing the pad are dodgy.

Also noticed last time I bled them when I removed the rear pads it looked a bit gunky and slimy around the calipers. I suspect that I have oil leaking out from the calipers or the seal between the two halves of the caliper.

Going to take another look after upcoming race and might try getting them warrentied. Bought online though so not holing out much hope...


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## Mark16q (Apr 16, 2006)

Bizarre but likely from minor leak in caliper.pull the pads next time but leave them in the same room to see what happens?


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## Cleared2land (Aug 31, 2012)

*Yeah, sounds like a caliper leak and some bleeding necessary. Of course just bleeding is a very short term fix if you've in need of a caliper seal.

Racing on compromised brakes huh? I would at the least do a bleed job before the race. This is one of the few situations where I would do a top down bleed given the origin of air would be at the caliper.*


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## matto6 (Dec 28, 2013)

Cleared2land said:


> Yeah, sounds like a caliper leak and some bleeding necessary. Of course just bleeding is a very short term fix if you've in need of a caliper seal.


Why do you say bleeding is needed? It doesn't feel soft or spongy at all. It just has no bite. It feels like a coefficient of friction at the pads kind of thing.


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## Njhardrock (Feb 17, 2013)

Try scuffing the rotor up with some sand paper and clean them ... Then try them out... I kinda feel when they get contaminated there really is no great save... I just lost a pair of barely used icetech rotors due to sitting


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## PerthMTB (May 2, 2011)

Does it get pretty hot in your basement - boiler down there or something? I have the same when my bikes have been sitting in the shed in my garden for a few weeks during the summer heat. I'd assumed it was a bit of oil weeping past the piston seals due to the heat causing expansion. Seem to return to normal after the first few minutes of a ride, with the help of a bit of deliberately heavy braking to help burn off any contaminants.

I read somewhere that Shimano brakes can only release pressure from the system by actuating the lever, otherwise they are a 'closed' system. So if they heat up in a car interior during the summer for example, expansion may cause oil to escape from the weakest part of the system - the piston seals.


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## Cleared2land (Aug 31, 2012)

matto6 said:


> Why do you say bleeding is needed? It doesn't feel soft or spongy at all. It just has no bite. It feels like a coefficient of friction at the pads kind of thing.


*
Ok, I should have replied with a quote from skinnybeans (below). Obviously, I wasn't replying to Matto6 because Matto6 didn't say anything about the caliper looking "gunky and slimy" or "having oil leaking around caliper". If your caliper is leaking then you likely have introduced air and thus a bleed would be required.*



skinnybeans said:


> I'm having issues with my rear XT. Front works great but the back has much less power and squeals. It lever feels firm but just no stopping power so guessing the pad are dodgy.
> 
> Also noticed last time I bled them when I removed the rear pads it looked a bit gunky and slimy around the calipers. I suspect that I have oil leaking out from the calipers or the seal between the two halves of the caliper.
> 
> Going to take another look after upcoming race and might try getting them warrentied. Bought online though so not holing out much hope...


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## dragbike (Jun 10, 2005)

I can't believe this thread is on here I came on to post about the same situation with my Shimano SLX brakes(latest generation). Rode my mtb for the 1st time since November. Bike was stored in a dry basement, upright. Brakes were fine when bike was last ridden. I took the bike for a road ride tonight and the brakes squealed like a pig. Back brake felt like it had no bite at all, front had some. levers felt normal. I took some automotive disc brake cleaner and wiped off the rotors and the rag really took off a lot of blackish grime? gunk?. This helped some but still not ideal at all. I will look at pads tomorrow.

Could what ever brake dust and grime that was left on the pads and rotors, from the end of last season, have hardened into some sort of film or glaze that just needs to be burned off? Like they need to be bedded in again, like when the brakes are brand new?


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## thickfog (Oct 29, 2010)

Guys, guys..... This is simply your bike telling you "don't you ever go this long again without riding me".


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## dragbike (Jun 10, 2005)

Thought I'd pass this info onto you guys. Above I reported the same problem with my SLX brakes. I cleaned the rotors with automotive brake disc cleaning spray. A lot of grime(brake dust?) came off the rotors. I then pulled the brake pads and also cleaned them with the same cleaning spray. again a lot of black grime(brake dust/dirt?) came off the pads. I unbolted the calipers and inspected inside where the pistons are. I could see no traces of any fluid but there was lots of brake dust. I thoroughly cleaned the calipers too but with rubbing alcohol.

I then went on my first trail ride of the season, about an hour ride. At first the brakes still felt the same- plenty of power and correct lever feel but no bite. About 1/2 into the ride all of a sudden the "bite" started returning, even to the point that I went into a skid a few times. By the end of the ride the brakes felt pretty much back to normal, more so in the front than in the rear. After my next trail ride I am hoping they'll feel 100% normal. I might bleed the back brake if it doesn't feel perfect.

Not sure why we are experiencing this issue but thought I'd share my findings.


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## machine4321 (Jun 3, 2011)

What pads are most of you on? Sintered or organic?


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## shiggy (Dec 19, 1998)

rfxc said:


> What happens to shimano brake pads when my bike sits in the basement for 6-8 weeks without riding? Help me, I'm baffled.
> 
> Backstory:
> In the last 2 years, my wife have had over 7 bikes in our house each with either Shimano M98x or M78x brakes on them. They either came stock on a bike, or I bled them and installed them myself.
> ...


Dust. Just wipe the rotors with a clean damp cloth.


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## -Todd- (Jun 13, 2011)

Corrosion would be my guess, there's lots of metal in sintered pads. Leaks don't just happen overnight, it's likely the pads need a scuff and a re-bedding...


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## Son (Jan 9, 2007)

I have this same issue. I got my bike with 2013 XT brakes (don't know the type, just that they're not with the ventilated, finned pads) in September last year and rarely rode it during the winter. When the bike was brand new, the brakes were grippy as hell, genuinely one-finger brakes as two would've been too much. No I have to squeeze with two fingers really hard (esp. the front brake) to get them to lock. Especially the front one is really noisy, too. The bike has 300km on it!


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## Cleared2land (Aug 31, 2012)

Son said:


> I have this same issue. I got my bike with 2013 XT brakes (don't know the type, just that they're not with the ventilated, finned pads) in September last year and rarely rode it during the winter. When the bike was brand new, the brakes were grippy as hell, genuinely one-finger brakes as two would've been too much. No I have to squeeze with two fingers really hard (esp. the front brake) to get them to lock. Especially the front one is really noisy, too. The bike has 300km on it!


*All of these experiences are news to me, but I suspect it could have something to do with dust accumulation. I live where I am able to ride with some regularity through most of the winter. So, I can add that I have never seen this issue. Assuming there are no leaks and the pads haven't become contaminated, what else could it be other than some dust accumulation? I really don't know. I have experienced a similar braking situation when riding through very powdery, talcum-like sand and noted reduced braking efficiency something like described on one occasion.

Perhaps a good cleaning several times throughout the winter or during storage periods. I wouldn't squeeze the brakes until cleaned to possibly test the theory. I simply can't think of any other possibility that would contribute to this problem. *


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## dth656 (Feb 12, 2009)

hi all,

i was going to start a new thread, but thought i would pose a few questions on this one. i have saint br-M820 brakes (180mm front, 160mm rear) on my santa cruz nomad. they have been mostly fine since i got them. last week i took them to my LBS for a bleed, and when i got my bike back, the front brake had no power, and was squealing super loudly. i assumed that it would just require a bed-in, and the LBS said the same.

well, i tried pedalling around quite a bit, and i wasn't able to bed them in. took the bike for a ~15 mile ride with about 2k feet of descent, and while a little bit more power, not much. 

a few questions:

-i ride my bike 2-3x a week, and the winters here are mild enough in california that i ride year round, so i don't think it is the storage issue
-the rear brake is perfectly fine: full power, full modulation, no noise
-is it possible that the pads were contaminated w/ mineral oil or something else during the bleed procedure? i took it back to the shop and they sanded the pads and cleaned the disc again, but no change: very little power, lots of noise
-does anyone know if the saint's come w/ metal or resin pads stock? none of the shimano technical documentation seems to help

i wanted to ask before i order some new pads and swap them out--thanks in advance!


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## Cleared2land (Aug 31, 2012)

dth656 said:


> last week i took them to my LBS for a bleed, and when i got my bike back, the front brake had no power, and was squealing super loudly. i assumed that it would just require a bed-in, and the LBS said the same.
> 
> -is it possible that the pads were contaminated w/ mineral oil or something else during the bleed procedure? i took it back to the shop and they sanded the pads and cleaned the disc again, but no change: very little power, lots of noise
> -does anyone know if the saint's come w/ metal or resin pads stock? none of the shimano technical documentation seems to help
> ...


*First, If you did NOT have new pads installed, then there is no reason to 'bed them in'. That's only a new brake pad requirement.

Second, if the brakes were working fine before the LBS bleed them (other than the necessary bleed for which you took the bike in for), I would have to assume that they indeed were responsible for the issue. To further the inquiry... is your front brake lever soft or spongy or is the only apparent problem a lack of friction (pad to rotor) such as might be experienced with contaminated pads. My question is really trying to determine if the bleed job was not done correctly or inadequately, or do you think it's a contamination problem?

Either way, I would place the problem back to the LBS. That is unless you had a contamination issue before you took the bike in for a bleed. It does sound like they are contaminated and just sanding will not correct the problem. If the LBS is responsible, they should either correct your problem or replace the pads.

Regarding your brake pads, look on the back of them to determine what you have. If metal, I believe the part number will begin with a M. Such as M06. I think, but not sure that the resin or organics begin with an F.*


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## dth656 (Feb 12, 2009)

thanks for the feedback cleared2land. both levers that were bled feel crisp, and not spongy at all, so everything good there. it's more the lack of power in braking, or as you said, it feels like the coefficient of kinetic friction between the pad and rotor is much less now, leading me to believe its pad contamination. 

i'll order new pads and a shimano bleed kit on monday (having watched quite a few videos on bleeding shimano brakes), so henceforth, i'm hoping to just service them myself.


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## Son (Jan 9, 2007)

Cleared2land said:


> *All of these experiences are news to me, but I suspect it could have something to do with dust accumulation. I live where I am able to ride with some regularity through most of the winter. So, I can add that I have never seen this issue. Assuming there are no leaks and the pads haven't become contaminated, what else could it be other than some dust accumulation? I really don't know. I have experienced a similar braking situation when riding through very powdery, talcum-like sand and noted reduced braking efficiency something like described on one occasion.
> 
> Perhaps a good cleaning several times throughout the winter or during storage periods. I wouldn't squeeze the brakes until cleaned to possibly test the theory. I simply can't think of any other possibility that would contribute to this problem. *


Definitely not a dust issue with mine, the bike's been ridden only in the winter, partly in snow, too.

I have a buddy working for Shimano and he'll ask their support guys if they've heard of this before. He said they have such few warranty cases that practically every warranty case is approved.

A friend bought a mountain bike last year with XTR brakes that were like a year or 1.5 years old and they were just like mine, lacking in power. And the previous owner took the bike to the LBS for regular services, so I don't think he was the neglecting type. This friend of mine got the brakes serviced. She has no previous experience in disc brakes, so she has no idea how powerful they should be. Hence it's a little difficult to check with her, if they work perfectly now. She's also the type who'll just pay to get her bike serviced, so she won't know what was done to the brakes to fix them.


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## Cleared2land (Aug 31, 2012)

dth656 said:


> thanks for the feedback cleared2land. both levers that were bled feel crisp, and not spongy at all, so everything good there. it's more the lack of power in braking, or as you said, it feels like the coefficient of kinetic friction between the pad and rotor is much less now, leading me to believe its pad contamination.
> 
> i'll order new pads and a shimano bleed kit on monday (having watched quite a few videos on bleeding shimano brakes), so henceforth, i'm hoping to just service them myself.


*Hmmm...I guess that I'm a little confused. You say that your brake levers feel crisp and not spongy at all. If that's correct, then there is no reason to bleed them. Bleeding them will not offer anything better than you have right now. If in fact your issue is in the pads (contamination) then you need to address that issue, not bleeding.

If you have metal pads, you have an option available to you that is not recommended for resin pads. Baking them. You can scrub the pads with acetone, MEK, or alcohol and place them in the oven to bake. Everyone seems to have a slightly different "recipe" for doing this in terms of how hot and how long. A brief search here should yield you some additional information on that. I would try that before dropping the money on new pads. If that fails, then you were getting new pads anyway.*


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## JuliusHettig (Sep 1, 2008)

I'd like to point out another culprit that can contaminate front brakes...

I've had an instance where my fork was slowly leaking oil onto my front brake. It is also an XT M785 and I lost all friction between the rotor and the pads, but the lever felt fine. I took it for a ride and the friction eventually came back to 100%, but on my next ride it was slippery again. I cleaned my rotor and installed new pads and also installed new crush washers for my RS Pike's lowers and everything was back to normal.


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## Triaxtremec (May 21, 2011)

I also had the same problem when the bike sits over winter. I simply took my pads out, put them in the oven at 350 degrees for 10 minutes. Let them cool, reinstalled the pads, and never had another problem...


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## dth656 (Feb 12, 2009)

ooops, sorry i should have been clearer. i took the bike in because both brakes did need a bleed, but they were otherwise fine (i.e. full power and modulation). the bleed successfully addressed the lever feel, but at the expense of the front brake being contaminated. 

i would only purchase the bleed kit to keep handy for future use (to avoid the LBS from now on!)


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## Cleared2land (Aug 31, 2012)

Interesting note...when I had Avid Elixers, the nessesity to bleed was an ongoing issue, so I sprung for a professional bleed kit and learned to become really good at bleeding those silly Elixers. Finally, I got so tired of the ongoing problem that I sprung for Shimano XT's. In 4000+ miles, I have only had to bleed them one time. WOW! 

The moral of my story DHT, is that you might never need that bleed kit that you're buying. But, I would definately suggest you buy one just in case.


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## pimpbot (Dec 31, 2003)

rfxc said:


> What happens to shimano brake pads when my bike sits in the basement for 6-8 weeks without riding? Help me, I'm baffled.
> 
> Backstory:
> In the last 2 years, my wife have had over 7 bikes in our house each with either Shimano M98x or M78x brakes on them. They either came stock on a bike, or I bled them and installed them myself.
> ...


Easy... check for fluid leaks. I'm fighting the same issue right now.

I'll bet pot brownies to poundcake that if you took the pads out and hit them with a torch, they would smoke off a bunch of brake fluid. Try that, and cleaning the rotors with brake cleaner. The brake cleaner or isopropyl alcohol will leave a bit of a residue that burns off after a couple hard stops. Throwing out brake pads because of brake fluid contamination is like throwing away clothing instead of doing laundry.

And, I'm not convinced that bleeding brakes will do anything for this issue. If the issue is that the seal is contaminated with a speck of dirt, allowing fluid to seep out, then sometimes you get lucky by being able to clean the seals (brake fluid on q-tip around the extended pistons and seals as much as you can reach) but that is really a hail mary.

Yeah, and brake bleeding is pretty easy, especially with Shimano brakes. You just need a bottle of brake fluid (I bought the liter size for $25... lifetime supply!) a 7mm wrench and a bit of 1/4" ID (IIRC... might be 3/16") clear vinyl hose you can get from the hardware store. You will also need the little yellow plastic block that goes in the caliper to set the piston spacing/system fluid volume correctly. Just make sure you chase all of the air out of the reservoir with the rubber bladder. I say do it a couple times, and you'll get a feel for it. No need to bug the LBS for that one.


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## extremedave (Aug 25, 2011)

I have the exact same issue as the OP. Still have to try some of the remedies but glad to see I'm not insane. My bike is also stored indoors, upright and kept clean. Bought the brake set last season (XT and IceTech). It's a little disappointing as I've loved the brakes until now. Will keep this thread posted on what works.. or not.


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## Cleared2land (Aug 31, 2012)

Some folks seem to be getting positive results from baking or torching. Several threads or comments around. Should be able to find some good information.


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## rfxc (Oct 18, 2004)

Thanks folks, keep the stories coming, maybe we'll find a remedy.

I started this post because I believe somehow the pads soak in moisture from the air, something, to get contaminated or glazed after use then sitting idle.

My lbs reports similar stories, they have slx/xt/xtr demo bikes that will get used every couple months, and after sitting idle, the pad/rotor have very poor friction.

I should also mention, I live in the midwest, so our climbs are short, rarely are you braking long enough to "burn off" anything.

My wife took her pads out, sanded them, then put them in the oven at 450deg for 30 mins, pads came back to life. Huh.


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## extremedave (Aug 25, 2011)

Took off the pads last night and the braking surface was quite black. A little sanding (used a sharpening stone just 'cause it was handy and flat) brought them back to the normal tan/copper coloring. Cleaned the rotor with some alcohol and it definitely felt better riding around the basement. Hopefully will get out this weekend (banged up my leg crashing so I've been off the bike a couple weeks) and see if it holds up. Probably try the oven if this doesn't work. I'm sure the wife will give me the WTH are you doing NOW?! look. 
Thanks.


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## mtb1983 (Oct 29, 2013)

Similar problem here - poor braking after the bike was put away for a couple of months - one pad was pretty dark. Took them off and put them in the BBQ - once they stopped smoking I sanded them a bit, and now no more problems. I suspect a leaking caliper (potential Shimano defect?). This is on a set of 9 month old SLX675's. The front brake has already been replaced under warranty by Shimano - I suspect the rear has a tiny leak...


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## Gunnar-man (Mar 21, 2008)

Add one more person to this issue except that one day it was fine and then next it wasn't.
Seached the inter-tubes and decided that it could be the hose and/or banjo bolt on the caliper. Bought a new set of hoses and fittings from Jagwire, installed them, sanded the pads and rotors and did a few runs down a steepish hill by my house to bed them in and the squealing and lack of power have disappeared.

Hopefully, that is the end of that. I do appreciate how unbelievably simple shimano brakes are to bleed compared to Avid/Elixirs.


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## Kanik (Sep 28, 2011)

I've experienced the same thing. I also suspected leaking oil at first but I don't believe it is the case (I couldn't see any trace of oil). I suspect it is just a case of the pad material reacting with the air, such as an oxidation reaction or something like that. 

It was happening on my front brake which is an XTR 1 piece caliper with F03C pads (metallic ice tech), but not on my rear brake with an XT caliper and B01S pads (resin, not designed for this caliper, but they work and I can get them free). 

The usual fix was to just ride and use the brake. I have gotten used to dragging the brake for a bit when starting a ride before I would need to do any actual braking, so that there would be some power. I believe this is normal for disc brakes. Some automotive brakes drag all the time to prevent this from happening, but obviously we don't want that on a bike.


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## limba (Jan 9, 2004)

Same here for me with XTR. Bike sat for 4-5 months in the basement. I was forced to ride it today, no power and howling.


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## newtrout (Jul 7, 2009)

I just had an experience with this that might be relevant. 2014 SLX brakes, but obviously similar to the XTs. Bike hadn't been ridden for a while, and had very weak stopping power and loud squeal under all conditions. Brakes had been completely normal on the last ride a few months back. I went out on a ride anyway. Horrible braking for the first 30 minutes of the ride, then I hit the downhill section. For the first mile of downhill there was no change, then over a 30 second stretch they were back to full power and normal. They weren't particularly dirty or dusty; stored inside; never above 80 degrees.

For those of you with similar issues, you might just get out and ride it for an hour. Put a pretty good load on them, get some heat in them, see what happens...


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## rfxc (Oct 18, 2004)

Yep. Thanks folks for helping me feel like I'm not crazy.

Between wife and I, 5 bikes have latest gen shimano brakes in my house, 2x XTR, 2x XT, 1 SLX. Wife put the perfectly running XC bike aside for 6 weeks, rides the enduro bike, gets the XC bike out of the basement... sure enough, squealing, etc. It's happened to both of us with different bikes, organic and metallic pads from shimano. 

I can only assume that pads somehow glaze over or oxidize while sitting unused, and that has to be burned off in a long and noisy bout braking-- which is hard to come by in Omaha, where the longest descent around is maybe 90 seconds 

Should I have any reason to believe that swiss stop or kool stop brand pads would behave any different? I'm tempted to try.

Sanding & baking our brake pads every time a bike has been sitting idle for 6 weeks is kind of a PITA.


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## BuickGN (Aug 25, 2008)

I now have this same problem. It was never a problem with the facotory Deores or with the metallic, finned pads swapped in the Deores (or maybe the bike never sat that long when it was brand new). 

Now that I've had the Zees on for a while I've noticed that if it sits for more than 2 days, braking power is gone. It doesn't come back with the first stop as the pads warm up. Heat seems to have nothing to do with it. I have to drag the brakes for quite a long time and then all of a sudden in a matter of seconds I'm at full braking power again and it stays that way even if I let the bike sit for 5 hours and come back to it. 

This has to be some sort of change happening to the pads while they sit. I washed the bike for the first time the other day and dried it well, using compressed air in cracks and crevices plus I rode it and dragged the brakes to get them hot. The next day they were the worst they've ever been . I'm convinced it's some sort of oxidation. Hopefullly my LBS carries Saint/Zee pads. I'm going to switch to the finned organics if they make such a pad for the Zees, just to prove it's a pad issue. 

The rotors look normal. No oxidation and a nice transfer layer laid down. No brake fluid contamination. I've pulled the pads off before and after re-breaking them in and the pad surface looks slightly different before and after.

I love Shimano brakes and I have no plans on jumping ship but they really dropped the ball with this latest round of pads with the pad material falling off and now oxidizing. My dog ran out in front of me as I was leaving the house and these brakes normally have huge power so I grabbed the brakes and I had little stopping power. I finally had to squeeze them so hard I thought I was going to break the lever and I barely stopped in time. Normally I can endo or lock the front tire on concrete with one finger and not much effort. The incident with the dog was the first time it happened so I was kind of pissed.

Just to clarify, the lever feels normal. This is not air in the system or an alignment problem nor a slave or master problem, it's a friction problem.


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## helexia23 (Jul 26, 2006)

Same. Around 12/2014 I put one of my bikes in the garage, with at the time, brand new XT brakes with the finned resin pads. They worked perfect when I hung it up. Got it out the other day and now they barely work, and squeak like a mo-fo. I cleaned the rotor and a bunch of black grime came off. Applied brakes again and rotors were all grimey again.

I had a pair of metallic pads from another bike and installed them and the brakes now work perfect.


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## Cleared2land (Aug 31, 2012)

I would have to assume a bike that has been in storage and not ridden for 10 years could exhibit a number of problems. You're surprised?


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## helexia23 (Jul 26, 2006)

Cleared2land said:


> I would have to assume a bike that has been in storage and not ridden for 10 years could exhibit a number of problems. You're surprised?


Hey at $20 a pair, I expect my brake pads to last at least 15 years. Good catch though, 2014


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## brentos (May 19, 2006)

Every pair of the current generation aluminum caliper XT or XTR brakes I've owned have done this. One set would leak enough oil out the pistons to make accumulated snow on the caliper yellow. Strange though that it's not enough fluid to need frequent bleeding.

I've now had two pair of the XTR M-987 Magnesium caliper brakes, they do not have the same problem. My favorite brakes, ever.


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## helexia23 (Jul 26, 2006)

To follow-up, I took sandpaper to the pads and the brakes now work perfect. I am assuming they were more covered in dust then any type of oil. When pads are contaminated with oil, sand paper almost never works.


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## jimPacNW (Feb 26, 2013)

Mine did the same thing sitting for 3 months over the winter (fronts worse than rear), in my basement which is cool and mostly dry. After sanding they did wake back up, I'll bet it's a thin layer of corrosion on the metallic pads. I know copper can get a thin slick green layer on it, so maybe something similar is happening. Baking would work better than sanding because it turns the corrosion from slick to dust that can burn off more easily, and dry out any moisture accumulation that's deeper into the pad material. Sanding would just remove the upper layer, but you'd have to sand a lot to get it all. If baking them is the answer after sitting, it shouldn't take more than 250f to dry them out. If it is a layer of oxidation; putting a rubber band or strap around the lever while stored to keep the pads on the rotors would keep them out of the open-air, and maybe slow/stop the oxidation? -just my 2c.


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## Argus (Jul 13, 2011)

I also have the same problem, I'll see how it goes after the first rides when snow will melt. I also remarked something : my levers are kind of oily after sitting there for a while; not only the levers but it's kind of oily near the freestroke adjustment screw and the reach screw. Nothing is dripping or accumulating, but there is enough oil to want to wipe it off with a rag. I don't feel any loss of power when squeezing the brakes. Does anybody has that on their brakes too ?


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## testrat (Aug 6, 2014)

I've also just suffered this problem but my bike only stood for 3 weeks. It was also only the rear brake. Just identified that the bleed nipple was passing fluid slightly. Found out by cleaning everything up and then using a cable tie to lock the brake on. I'm getting a new set of pads but worth checking the bleed nipple isn't leaking.


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## 92gli (Sep 28, 2006)

In my experience, the brakes in question only squeal when mineral oil gets on the pads. I've had it happen once by accident (my fault), and a second time due to a faulty caliper piston seal on my new road bike. I kinda doubt dust is the issue.


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## rfxc (Oct 18, 2004)

Great follow up guys. I'm still dealing with the issue, but I've gotten pretty quick at removing and cleaning pads on a bike after it's sat idle for awhile. Most of the time, sanding is not adequate. But after a quick hit with a propane torch or my natural gas stove and they are fine. 

couple interesting points above.
Brentos says it doesn't happen with his 987 magnesium caliper brakes. Interesting. This supports the notion that there may be a slight design flaw in the 985/785 brakes where oil (very slowly) creeps out around the pistons and contaminates pads after a time. Seems most likely this is whats happening.

another idea presented above. store the bikes with a rubber band on the lever, keeping the brakes compressed. Question: will storing bikes with the brake lever depressed put more pressure for oil to seep out of the caliper/piston area, or will added pressure and movement/changed position of the piston/seal prevent oil seepage?


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## 92gli (Sep 28, 2006)

rfxc said:


> Great follow up guys. I'm still dealing with the issue, but I've gotten pretty quick at removing and cleaning pads on a bike after it's sat idle for awhile. Most of the time, sanding is not adequate. But after a quick hit with a propane torch or my natural gas stove and they are fine.
> 
> couple interesting points above.
> Brentos says it doesn't happen with his 987 magnesium caliper brakes. Interesting. This supports the notion that there may be a slight design flaw in the 985/785 brakes where oil (very slowly) creeps out around the pistons and contaminates pads after a time. Seems most likely this is whats happening.
> ...


Another thought - If you take apart one of the two piece calipers there is only a small O ring that seals the passageway between the two halves. It didn't appear to me that its under much compression. Maybe when the bikes sit for a while the O ring shrinks a little and seeps fluid. My bike is always stored upside down, so fluid doesn't run on to the rotors. If you store it right side up the fluid would drip on to the rotor.


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## eicca (May 9, 2014)

I've had M775s, M596s and M395s all do this to me and it drives me OUT OF MY MIND.

After they sit for a few weeks, they squeak and there's no bite, but the levers are plenty firm. It's like they glaze over when they sit.

I'm inclined to believe it's not oil leakage; after some riding, they return to full power.


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## Cleared2land (Aug 31, 2012)

I too have experienced the same problem as many here after extended periods of no riding on many occasions (I have three bikes with XT's installed, so they see some periods of storage). Firm on the lever pull, but an initial reduced braking effect. However, for me personally, the problem quickly goes away with a few hard braking attempts much like you would do when bedding new pads. Problem solved. 

I have no idea if it's dust, oxidation or whatever...but it's a minor inconvenience at worst. All this talk of leaks and seeping calipers is seemingly a little over the top and can be quickly diagnosed with a quick look. It seems this is a big deal to some, but they might be experiencing different problems. But it does seem to be the same problem.


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## ColinL (Feb 9, 2012)

Cleared2land said:


> I too have experienced the same problem as many here after extended periods of no riding on many occasions (I have three bikes with XT's installed, so they see some periods of storage). Firm on the lever pull, but an initial reduced braking effect. However, for me personally, the problem quickly goes away with a few hard braking attempts much like you would do when bedding new pads. Problem solved.
> 
> I have no idea if it's dust, oxidation or whatever...


Exact same experience on my wife's XT (M785) equipped bike. I looked and it has metallic pads. I look like an idiot on her tiny bike, but I go up & down the street about 10 times and burnish her pads to the rotors. They work just fine afterwards.

The last time this happened, I could actually see some discoloration on the front rotor. The rear was shiny and worked better, but the front was not grabbing well at all and when it did start to work I could see some shiny grooves in a darker pall. I think that's some kind of oxidation.

I'm shopping for resin pads now. I am not sure if she is using icetech or standard rotors... been a few years since I built this thing.  But I think it's the stock Shimano semi-metallic pad, so I'm starting there.


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## eicca (May 9, 2014)

ColinL said:


> I'm shopping for resin pads now. I am not sure if she is using icetech or standard rotors... been a few years since I built this thing.  But I think it's the stock Shimano semi-metallic pad, so I'm starting there.


I've had it happen with both resin and metallic.


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## aerius (Nov 20, 2010)

New data point. I finally got a new set of metallic Ice-tech pads for my Saints, which were working totally fine on the old and now worn down pads. Cleaned all the dust & crud out of the calipers, put the new pads in, got them bedded in nicely and a couple days later they had no braking power. Burned them back in with a few hard stops and they were back to full power, put them away overnight and most of the power was gone. Decided I didn't want to deal with this crap anymore and popped in a set of metallic M810 Saint pads and everything worked as it should with no power loss after storage. So it's definitely the pads, not a leak in my brakes. I figure I'll just save the Ice-tech ones for DH days where I can quickly burn them in on the first run.

For what it's worth my original pads came with the brakes which were ordered from Europe a couple years back. The new pads came from Shimano's North American warehouse in the US.


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## ColinL (Feb 9, 2012)

eicca said:


> I've had it happen with both resin and metallic.


Hmm. Is it the icetech rotor oxidizing?

Isn't it some kind of aluminum and steel sandwich?


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## Mauri (Mar 17, 2010)

I had this exact same issue with 2 sets of SLX and Saints, both latest generation. The Saints were the worst. The bike was in a dry, cool basement for wintertime (fat bike season) and when I rode in spring there was zero bite and power. I Cleaned the rotors and sanded a bit of the surface of brake pads, but the power never came back. I checked for leaks, but there was none.

With 2 sets of SLX, XT and Saints all lost power and bite after use, slowly but Gradually. I've heard few others reporting the exact same issue. 

After these experiences I went for Hopes for my latest build.


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## aerius (Nov 20, 2010)

ColinL said:


> Hmm. Is it the icetech rotor oxidizing?
> 
> Isn't it some kind of aluminum and steel sandwich?


It's definitely not the rotors since I run standard steel rotors on my bikes, and only use the Ice-tech rotors for DH days at the bike park.


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## ColinL (Feb 9, 2012)

aerius said:


> It's definitely not the rotors since I run standard steel rotors on my bikes, and only use the Ice-tech rotors for DH days at the bike park.


Ok, excellent to know.

People are saying it happened to them with both organic and semi-metallic Shimano pads.

What about non-Shimano pads? There are a variety - Galfer, TruckerCo, Jagwire and so on. I'm curious if someone has put on 3rd party pads and whether the issue remained or was corrected.

It has to be something specific that we can narrow down...


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## Prophet Julio (May 8, 2008)

I have an older set of XTR's on my Prophet. If it sits for a long time, I get the same thing. It happens with Shimano pads and Truckerco pads. After a Brake Clean spray and wipe and some high speed street runs with frequent stopping, the squeal goes away and the power returns. I am currently using Truckerco pads. It seems to have nothing to do with the calipers. In my experience, when oil gets on the pads there is no saving them, they are junk. This is a different phenomenon. Perhaps as the disc brake community has expanded and grown there is a slime mold organism that has made disc pads there preferred home? A new species? Evolution!


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## Cleared2land (Aug 31, 2012)

I have to comment here regarding this issue.

I have experienced the reduced braking as I stated in an earlier post, but I have NOT experienced any noise or squealing in the process. Brakes remain quite, but with reduced braking ability.


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## BuickGN (Aug 25, 2008)

I wouldn't condemn the resin pads yet. Just one person has had the issue with them and he also has a squeal which isn't really a normal symptom the rest of us are having. The noise plus loss of power usually points to contamination. 

For what it's worth, the Zee/Saint "resin" pads have a good bit of metallic content. I would call them a semi metallic more than a resin pad. They have been flawless no matter how long the bike sits. The sintered pads on these brakes had the issue way worse than the sintered on my XTs. It could be due to the extra surface area of the Zee pads, it would definitely take longer to wear off any oxidation layer.


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## tiflow_21 (Oct 27, 2005)

I have this problem as well. While it generally seems to resolve itself after a brake heavy ride, a recent pair of resin pads has been giving me a he!! of a time. Finally blasted the pads with a propane torch. After a quick bed in loop around the block they seem back to normal. Time will tell.


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## Schmucker (Aug 23, 2007)

Same problem here! Only the rear on XTR M988. The front feels great. Rear HOWLS and has no power after sitting for the winter. I put new pads (Kool-Stop) in last fall because the stock pads are garbage. I'll try torching the pads.


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## Bent Wheel (Oct 6, 2007)

Anybody try doing the figure 8 on a piece of sandpaper to freshen up the pad?


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## Cleared2land (Aug 31, 2012)

Bent Wheel said:


> Anybody try doing the figure 8 on a piece of sandpaper to freshen up the pad?


No, but sprinkling a little lemon water on them freshens them up nicely.


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## jimPacNW (Feb 26, 2013)

I have taken my pads out and run them over a sanding block a couple of times, along with sanding the rotor with really fine grit paper. That has helped, and my brakes are working well now. I'm going to try baking them next time I let them sit for a long time. Schmucker: did yours come with the metallic pads? I can't imagine not liking those.


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## Trial11 (Oct 5, 2011)

Another 987 user here, no issues after all winter of sitting in my basement. Are the pads the same between 985 and 987?


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## Carmel (Apr 21, 2014)

I had/have the same problem on my 2014 Slx m675 brakes. Had the bike sitting over the winter, when I took it out again no power. Cleaned the pads (resin), used sandpaper, scuffed the rotors, tried to re bed them. After sitting for a few weeks power was lost again and I sometimes had to pull very hard to stop at all. Especially the rear brake did squeal/howl on those occasions. Did this twice and after a longer ride they now seem to be halfway back to normal, but power is still subpar when compared to other SLX brakes on a buddies bike. 
Has anybody tried to claim this to Shimano? I guess they would put it off as contamination, but maybe worth the try.


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## Cleared2land (Aug 31, 2012)

Interesting that I have experienced the same issues as everyone has described, but I have never sanded rotors or pads. A few hard braking maneuvers as if bedding in new pads and everything was like new. All of this sanding seems a bit overzealous.


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## eicca (May 9, 2014)

I've been riding to work for a week now and so far my front brake had kind of returned to normal. Still a little noisy and feels weaker than usual. My back brake is still just as bad as when I first got my bike out. Pisses me off. I can't see any evidence of leakage so far, I'll pull the pads and sand them and see if I can't get them worked into shape. Maybe they're "glazed" so bad they can't generate enough heat to wear down.


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## eicca (May 9, 2014)

Also, I was just chatting with my mechanic friend about this case and he says the only thing he can think of that would cause what we've been experiencing is dust collecting on the pads and then burning and glazing when going for a ride. I'm inclined to think this is worth further thought since nothing else really make any sense


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## eicca (May 9, 2014)

Further update: I pulled my pads and they looked glazy, like a donut. So I sanded them, 32 small circles each facedown on the sandpaper. The difference was very visible. I cleaned the rotors with alcohol and reinstalled the pads, and now they feel just like brand new brakes needing to be bedded in. Night and day difference.


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## BuickGN (Aug 25, 2008)

eicca said:


> Also, I was just chatting with my mechanic friend about this case and he says the only thing he can think of that would cause what we've been experiencing is dust collecting on the pads and then burning and glazing when going for a ride. I'm inclined to think this is worth further thought since nothing else really make any sense


It's not likely dust as mine would lose power as quickly as 24hrs after my last ride sometimes. Mine weren't so horrible until I got the brakes good and hot one day but maybe that's just my bad memory.

I always wanted to try sanding them because I figured it would speed up the process but after almost running over my dog I swapped to resins and never looked back. Power was so low that I couldn't lock up the rear tire on a brake that's usually so powerful I can put myself over the handlebars easily with one finger. It really was a safety issue with how much power mine lost when sitting. When my dog ran in front of me it was t even close. I hit both brakes, no power, so I put my feet down. It was worse than my Tektro mechanicals on 160mm rotors.


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## eicca (May 9, 2014)

I'm now 100% certain the pads glaze themselves while they sit. I can feel the difference between coming home from work and then riding the next morning. They literally foul up overnight. I pulled the pads and inspected the calipers and they're bone dry. No leaks. This is driving me INSANE. I wonder if Shimano will warranty them.

Has Shimano acknowledged the issue? Offered any kind of statement? Anything?


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## Bent Wheel (Oct 6, 2007)

Try just sanding the pads and don't clean the rotors, see if that helps. Rebedding may be having an ill effect on the pad after sanding them.


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## eicca (May 9, 2014)

Bent Wheel said:


> Try just sanding the pads and don't clean the rotors, see if that helps. Rebedding may be having an ill effect on the pad after sanding them.


I'm willing to give it a try. Tell me more about your thought process though; would leaving pad material on the rotor transfer it back to the pads and prevent glazing?

I feel like this issue has consumed my life. It's like CSI: MTBR or something.


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## Cleared2land (Aug 31, 2012)

Just sprinkle pixie dust on your calipers before bedtime and everything will be fine in the morning.


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## Bent Wheel (Oct 6, 2007)

I don't think you can prevent glazing totally. I do think that cleaning the rotor and rebedding is causing the quick glazing issue you are having. I don't clean my rotors, so I haven't experienced this quick glazing issue. I've only sanded my pads once in the 6 months I've had them. Give it a try, we both might be surprised.


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## BuickGN (Aug 25, 2008)

Just one quick point, the pads can't glaze by definition while sitting. That's why I believe it to be corrosion or some chemical change after getting hot and being exposed to air while sitting. I hope it has nothing to do with the aluminum/stainless sandwich of the rotors. I think earlier in this thread someone had removed the pads after a ride and they still had the problem but I don't remember for sure. 

For a brake to work properly the pads must lay down a transfer layer on the rotor. Once this is done, wear (rotor and pad) and noise drop greatly and power is much improved. By always removing this layer you're starting all over all the time. I'm not sure it has anything to do with this particular problem but a transfer layer is important. Hell, maybe the transfer layer on the rotor is what's changing while sitting.


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## aerius (Nov 20, 2010)

Bent Wheel said:


> Try just sanding the pads and don't clean the rotors, see if that helps. Rebedding may be having an ill effect on the pad after sanding them.


Tried it out of curiosity today, it works. I gave the pads a quick sanding with 400 grit sandpaper, sanded it just enough so that a bit over half the pad was showing the nice copper colour of the metallic compound. I did not do any cleaning of the pads or rotors. I had about 80% power on the first stop, and full power within 4-5 stops. It remains to be seen if the pads will keep going to shít overnight and if the sanding needs to be done before every ride.

I can confirm that it has absolutely nothing to do with the rotors or calipers since I use the regular all steel rotors on my bikes and have pulled the pads and put them into storage immediately after a ride. And yet I still have the issues.


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## Havinfun (Mar 18, 2015)

Wow, lots of problems with the Shimanos, maybe five years from now people will be hating on Shimano brakes and loving SRAMs, especially given the new Guides....


Before you flame me, just think about this and the last 15 years of bikes brakes, also I love my XTRs and I am hoping I do not get the chance to experience this new problem.


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## Cleared2land (Aug 31, 2012)

I've got a XT equipped Santa Cruz Superlight 29er that has become a spare (extra) ride for visiting friends. It doesn't get ridden too often and I just took it out for a trail ride and it seemed to have minimal, but notable brake fade and was initially braking at about 85%. Several hard braking applications seamed to restore the brakes back to 100%. That seemed easy enough. My regular ride has XT's and I used it as my benchmark braking comparison.


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## BuickGN (Aug 25, 2008)

Havinfun said:


> Wow, lots of problems with the Shimanos, maybe five years from now people will be hating on Shimano brakes and loving SRAMs, especially given the new Guides....
> 
> Before you flame me, just think about this and the last 15 years of bikes brakes, also I love my XTRs and I am hoping I do not get the chance to experience this new problem.


You really have a hard time understanding the most basic things based on this and your previous postings. There seem to be a bad batch of finned metal pads. These Shimanos are not leaving people without brakes. No frozen Pistons or levers that go to the bars. A bad batch of pads is way different than 10+ years of bad brakes. The Avids should have been sold as disposables. Buy a 6 pack and replace once or twice a year when they fail on you. These have lower power after sitting for the first mile or two before wearing off the layer of corrosion and getting full power back. If Avids only had issues with pads they wouldn't be despised by so many. This is one minor problem and it is with the pads.


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## BuickGN (Aug 25, 2008)

aerius said:


> Tried it out of curiosity today, it works. I gave the pads a quick sanding with 400 grit sandpaper, sanded it just enough so that a bit over half the pad was showing the nice copper colour of the metallic compound. I did not do any cleaning of the pads or rotors. I had about 80% power on the first stop, and full power within 4-5 stops. It remains to be seen if the pads will keep going to shít overnight and if the sanding needs to be done before every ride.
> 
> I can confirm that it has absolutely nothing to do with the rotors or calipers since I use the regular all steel rotors on my bikes and have pulled the pads and put them into storage immediately after a ride. And yet I still have the issues.


That's really good to know, I really didn't want to give up my ice tech rotors. I think by your sanding the rotors with no other changes during the problem it proves it's the pads only. The slightly reduced power at first would be normal break in.


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## BuickGN (Aug 25, 2008)

Cleared2land said:


> I've got a XT equipped Santa Cruz Superlight 29er that has become a spare (extra) ride for visiting friends. It doesn't get ridden too often and I just took it out for a trail ride and it seemed to have minimal, but notable brake fade and was initially braking at about 85%. Several hard braking applications seamed to restore the brakes back to 100%. That seemed easy enough. My regular ride has XT's and I used it as my benchmark braking comparison.


By fade, you're talking about lost power from the layer of corrosion, not actual heat induced pad fade, right?


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## Havinfun (Mar 18, 2015)

BuickGN said:


> You really have a hard time understanding the most basic things based on this and your previous postings. There seem to be a bad batch of finned metal pads. These Shimanos are not leaving people without brakes. No frozen Pistons or levers that go to the bars. A bad batch of pads is way different than 10+ years of bad brakes. The Avids should have been sold as disposables. Buy a 6 pack and replace once or twice a year when they fail on you. These have lower power after sitting for the first mile or two before wearing off the layer of corrosion and getting full power back. If Avids only had issues with pads they wouldn't be despised by so many. This is one minor problem and it is with the pads.


You are consistent. There are these problems, your problems with your Zees, the problems with squealing... But, you cannot have a conversation without trying to insult and you cannot own any problems. The best part is that it is so easy to get you worked up. Do your best insults, be the jerk you can be (not always, just when you don't like the opinions of others), but the fact is that Shimanos have multiple issues. In the end, though, both Shimano and SRAM have great products overall and that appears difficult for you.


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## dvzzz (Apr 27, 2011)

This behavior is not at all random, I have been through 3 pairs of breaks. Sent one of them to Shimano for warranty, they did replace Deore M596 with 2014 model. This riding season of 2015 and same exact problem, loss of breaking power, squeal. Exactly as 2013 model. I check very careful and do not see pad contamination. Shimano does not acknowledge the problem. They keep denying all photographed/documented facts that with winter glazing, with bleeding nipple that has tiny bit of sipping (yes torque to spec the nipple). Both 2013 and 2014 leak at the nipple but calipers are dry. Pads are clean from any mineral oil. I will keep sending to Shimano given that it has 2 year warranty and they need to really accept that they have an issue. If nobody complains then why would Shimano fix anything?


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## Havinfun (Mar 18, 2015)

dvzzz said:


> This behavior is not at all random, I have been through 3 pairs of breaks. Sent one of them to Shimano for warranty, they did replace Deore M596 with 2014 model. This riding season of 2015 and same exact problem, loss of breaking power, squeal. Exactly as 2013 model. I check very careful and do not see pad contamination. Shimano does not acknowledge the problem. They keep denying that fact that bleeding nipple has tiny bit of sipping (yes torque to spec the nipple). Both 2013 and 2014 leak at the nipple but calipers are dry. Pads are clean from any mineral oil. I will keep sending to Shimano given that it has 2 year warranty and they need to really accept that they have an issue. If nobody complains then why would Shimano fix anything?


You are probably going to be told that you are wrong and that you have never actually had these problems. Then, you might be insulted. Then maybe attacked, given the Shimano Fanboys can get that way.
But, the reality is that few people have problems with the Shimanos, usually they are great. But, like everything today, some will fail. And, some people will get the bad luck of having a few fail.


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## Cleared2land (Aug 31, 2012)

BuickGN said:


> By fade, you're talking about lost power from the layer of corrosion, not actual heat induced pad fade, right?


Yes, that is correct. The initial fade or loss of braking power experienced at the beginning of a ride on a bike that has not been ridden for a while.. Weather it's corrosion, or whatever, I'm not sure of. I do know that for me personally, It's not a significant issue.


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## eicca (May 9, 2014)

My bike has been sitting all weekend due to nasty cold rain. I fully expect to have crappy braking performance tomorrow. I'll try sanding just the pads and see if that changes behavior. If not, I'll get 'em warrantied and see if I can upgrade to a newer set and throw in some aftermarket pads.

Will post back with results.


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## matto6 (Dec 28, 2013)

For what it's worth, after riding my bike for the first time since winter, the brakes suck ass again. Damn near dangerous.

Last time sanding them did the trick. I'll try it again.


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## apuking (Mar 3, 2015)

Been riding on Shimanos for the past 7 years and am now running on the XTR M9000 Race brakes. Only once have I experienced such a problem and that was with mettalic pads after a bike clean where I might have gotten a bit of spray stuff on the rotors. The past 4 years I only used the Resin pads and have not experienced this problem, except from my brakes needing the occasional bleed or a change of pads.
I ride everyday through all kinds of weather.

Just check where you store your bike, how you clean and wash it and cotrol from time to time if you need new rotors, pads or a bleeding.
Oh and never in my life did I have the need to wash or burn or sanding my rotors.
Im not saying that there are no problems with the brakes, hell in the past they had quite a few issues with brakes leaking but that seems to have been improved a lot.


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## BuickGN (Aug 25, 2008)

Havinfun said:


> You are consistent. There are these problems, your problems with your Zees, the problems with squealing... But, you cannot have a conversation without trying to insult and you cannot own any problems. The best part is that it is so easy to get you worked up. Do your best insults, be the jerk you can be (not always, just when you don't like the opinions of others), but the fact is that Shimanos have multiple issues. In the end, though, both Shimano and SRAM have great products overall and that appears difficult for you.


Once again, instead of trying to say I'm wrong with facts or at least a factual based argument you get all emotional. You made a statement of "Wow lots of problems with Shimanos......". Not lots of problems. The same problem in almost every case which would be a problem with the pads, not the brakes themselves. You're so quick to make a blanket statement as if Shimanos have tons of problems. Leave your emotion and bias out of it and we can have a conversation. A bad batch of pads does not compare to all of the Avid brake failures that occurred over the past 10 years. I can't believe you would even go there. The Guides hopefully will prove to be reliable but only time will tell. It's been long enough that I'm going to finally pull the trigger on a set but I'm still a little leery of going with Avids again.

I can't admit problems with my brakes? I've stated every problem. The metal pads squealed and had no power but when I dug deeper I found that they were bent. What's the problem? I don't think we can blame Shimano and we definitely can't blame the brakes.

My Zees weren't bled properly when I got them so I bled them and they've been trouble free ever since, almost a year now.

I've been very vocal about the pads that corrode when sitting and lose power until I've ridden several miles.

I've inquired about the aluminum sandwich rotors melting and started looking into other brands' stainless 2 piece 220mm rotors. After the recent descents, I've realized that I can't get my rotors to melt if I try so I'm sticking with what's on the bike but I was about to jump ship until I dug deeper.

I'm sure I will be called a jerk for stating that I don't hate Shimanos lol.

To you, an insult is presenting facts that go against your beliefs so I'm not too worried about those accusations. You have at least 2 threads right now unprovoked throwing out insults to "Shimano Fanboys" and something about dying a slow death that myself nor other Shimano owners have posted in. They're just a chunk of metal, I don't have some undying loyalty to them as you seem to have.

I don't care if you have opinions no matter how wrong they might be but you state them as facts and that's where the problem is. I've given the Guides several good reviews, I'm getting ready to use them on my XC bike as I've stated numerous times but I can't admit that Avid has good products? Get over yourself. You've created this little battle of Avid vs Shimano. I've always kept my posts factually based and when I have an opinion I state it as an opinion and I usually explain how I arrived at that opinion or conclusion so others might be able to tell me if I'm right or wrong.

You on the other hand love to keep everything subjective and you flip out when there's a fair objective apples to apples comparison and your brake doesn't come out on top. I'm not the one comparing one brand's power with 160mm rotors to another brand's power with 203mm rotors. The different sized rotors were not brought up by you, luckily another poster was sharp enough to remember what you were running. You were going to compare the two brakes with drastically different sized rotors and not tell anyone!?!? Maybe a little bias here? Once called out you state that it's fair because the bike with the XTRs is 6 lbs lighter so it evens out!!! Wow. I hope you realize now that, that was an opinion and a severely misguided one. If you had done even a tiny bit of research you would have seen that 6lbs makes no difference compared to the rotor size difference but I don't think accuracy is what you're after....

After getting called on it and after the pads are bedded in, you say the XTRs are nice but you make no mention of power. You say you can't compare because the bike with the Guides is ridden under different conditions. Different conditions might test out the heat dissipation but all you need is to do a couple stops in your driveway to know which brake requires less effort for a given deceleration rate. It seems like you're purposely trying not to compare the power of the two. Remember, initially you exclaimed that the Guides are way more powerful and anyone who says they're not more powerful has never tried them or has tried both brakes. Once the XTRs are bedded in, you have no opinion of which one is more powerful all of a sudden because of different conditions but the conditions didn't stop you from that opinion at first when the Guides were stronger.

I would never compare brakes with different sized rotors and pads not bedded in, at least not without making it very clear in the comparison. I'm not the one saying 4 piston brakes are stronger than 2 piston brakes and the list goes on and on. You state your opinion as fact and get pissed off when you're proven wrong by actual facts and start calling us jerks. I enjoy learning so if someone proves me wrong it's fine, it means I learned something new. My entire worth as a human being is not centered around whether or not my brakes are the best in the world or whether I'm always right lol.

It's easy to see what's going on, you seem to have trouble telling the whole truth and you get very defensive when called on it no matter how nicely it's done. My stance between the two brakes has always been that power is so close that power should be the last thing anyone looks at when trying to decide between the two. I've said several times that I can see how some would like the lever throw and feel of the Guides better. There are subjective items, personal preferences which can sway a person either way but which brake has the most power on a level playing field is not subjective, the Shimano 2 pistons do have more power but it's so slight it probably won't matter to most. Who's the fanboy here?

I'm sure your reply is going to be more of the same. I'm a fanboy and I'm a jerk followed by some emotional knee jerk reaction with no facts to back it up and you will ignore everything said above.


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## BuickGN (Aug 25, 2008)

I wonder if Shimano is aware of this thread... It might be a good idea to make sure they're aware of this problem if they're not already aware. The resin pads for the Zees are very nice and pretty aggressive for a resin pad but it would be nice to have the option to run metals without being worried about noise and a lack of power. I think there's more than enough complaints with the same problems, some going back a few years, to get them to take action. I know I have $80 worth of pads just sitting in a box that I can't use and the last thing I want is to spend another $80 for pads that may or may not work right.


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## BuickGN (Aug 25, 2008)

Doing a search on this subject shows several threads starting around 2013 that seem to have the same issues. This is the first one that lists corrosion or even pads as the possible culprit but it looks like this problem might have existed for a while now but has never gained the momentum that this thread has.

I'm sure we're all in the minority or no one would be buying Shimanos with metal pads and most people run metal pads with no issues at all. But still, there seems to be a definite problem with them that needs to be addressed. If the pads cost $10 like many of the older ones did I probably wouldn't care so much but $80 for a set is too much to blow off or take a chance on.


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## eicca (May 9, 2014)

Just as predicted, rode to work and the brakes were slippery and noisy after only a three day sit. So I took them out and sanded them again but did not clean the rotor this time. Rode around and stopped hard a few times and they're back to their old one-finger endo/skid strength. We'll see how long that lasts... I'm calling Shimano if I hav further problems.

And I did confirm 100% they are resin pads. Says right on the back.

Before sanding, with visible glaze-over:








Sanded the pair on the right:








Sanded both:


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## ColinL (Feb 9, 2012)

Thanks for the pics, eicca. The 'resin' pad is of course semi-metallic and this metal is what is corroding. The actual metallic Shimano pads may contain a similar material.

Earlier in this very thread, others have commented about using non-Shimano pads and still having the issue, but I'm going to try a set of TruckerCo for my wife's bike. I'll bed in the pads very thoroughly.

BTW regarding leaking calipers, my wife's are fine, but my dad has a set of XT brakes (not sure if they are 785 or previous generation) and both his calipers leak.


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## eicca (May 9, 2014)

ColinL said:


> BTW regarding leaking calipers, my wife's are fine, but my dad has a set of XT brakes (not sure if they are 785 or previous generation) and both his calipers leak.


The XT M775s were somewhat notorious for leaking calipers. I had a set and blew the rear piston seal at the top of a canyon. Sketchiest downhill run of my life


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## aerius (Nov 20, 2010)

And it's confirmed, sanding is only a temporary fix and will be required before each ride if the brake pads have gone unused for a while. I rode the same pads today which I fixed via sanding a couple days and they're back to squealing with no power. Did another quick sanding on the pads alone and they were back to normal within 3-4 stops.

100% confirmed as a Shimano finned metallic pad problem. The good news is there's a quick fix, the crappy part is you need to do it all the time. I'll see if I can get in contact with the local Shimano reps and see what they say.


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## Havinfun (Mar 18, 2015)

BuickGN said:


> Once again, instead of trying to say I'm wrong with facts or at least a factual based argument you get all emotional. You made a statement of "Wow lots of problems with Shimanos......". Not lots of problems. The same problem in almost every case which would be a problem with the pads, not the brakes themselves. You're so quick to make a blanket statement as if Shimanos have tons of problems. Leave your emotion and bias out of it and we can have a conversation. A bad batch of pads does not compare to all of the Avid brake failures that occurred over the past 10 years. I can't believe you would even go there. The Guides hopefully will prove to be reliable but only time will tell. It's been long enough that I'm going to finally pull the trigger on a set but I'm still a little leery of going with Avids again.
> 
> I can't admit problems with my brakes? I've stated every problem. The metal pads squealed and had no power but when I dug deeper I found that they were bent. What's the problem? I don't think we can blame Shimano and we definitely can't blame the brakes.
> 
> ...


Same as always, you take a portion of what I have said and twist it, days later and paragraphs later.

I said that they were not bedded to qualify my initial impression and twice later stated guides as more powerful, in my opinion.

I mentioned the bike weight difference and load difference, you clinged to the bike weight only. Load was about initial response, not fade.

Shimanos have threads about squealing, pad issues (multiple), leaking. Not just one issue.

You do not mention I love my new XTRs and I am looking to get Saints. So, your argument about this being Shimano versus SRAM holds no water.

Glad I was able to get you to understand Guides are worth a look, you are welcome!


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## BikeIntelligencer (Jun 5, 2009)

Once I switched to third party pads the problem went away. While I hated the squealing what really drove me crazy was the fade.


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## eicca (May 9, 2014)

So when the pads were new I would ride once a week with no fade. Then all the sudden, after winter, they fade overnight. I wonder if absorbing moisture is the culprit. If that's the case, like others seem to have done, some time in the oven or a good hot downhill run should fix them for longer than a day.


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## ColinL (Feb 9, 2012)

aerius said:


> And it's confirmed, sanding is only a temporary fix and will be required before each ride if the brake pads have gone unused for a while. I rode the same pads today which I fixed via sanding a couple days and they're back to squealing with no power. Did another quick sanding on the pads alone and they were back to normal within 3-4 stops.
> 
> 100% confirmed as a Shimano finned metallic pad problem. The good news is there's a quick fix, the crappy part is you need to do it all the time. I'll see if I can get in contact with the local Shimano reps and see what they say.


I bought a set of Galfer pads for my wife's set of XT 785 brakes. They'll be here next week and I intend to clean the rotors and bed them in, and see how it works with her usual ~2 rides a week.


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## SHowley2003 (Feb 21, 2008)

This thread s fascinating. Thank you everyone for the info. I have struggled greatly with my brakes over the past few weeks. Long story short, upgraded to 2014 XTs last year and loved them. Winter in the northeast US this year meant the bike was stored in my basement for about two months. I took it out and I had zero braking power and the noisiest of brakes. I actually crashed rolling down a hill to the trails as I need to speed check and couldn't. The brakes are so consistently noisy that I am a joke at the trails as I can tap my brake levers as if they are musical instruments. I'm well versed in servicing bikes and I have tried everything short of replacing the pads. I've known it was a pad issue but I didn't want to buy new ones if this would happen again. I think I'll continue to sand them for now.


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## crrimson (Jun 26, 2008)

I found this thread because I have the same problem with my Shimano XT 785's. I rode in Moab after sitting throught he winter and my brakes were fine. I put the bike away for 2 months while having the fork serviced, and just took it out yesterday.

I found that the rear brake was squealing initially, but then this squeal went away. I started the ride and found that I had NO power at all in my rear brake, but had full power in the front. I would pull the rear lever hard and there was no stopping power, and I could not make the bike skid. I will try taking the blowtorch to the pads, cleaning the rotor with rubbing alcohol, and see if I can get this working...


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## eicca (May 9, 2014)

So I called Shimano and of course: "It's probably cooked rotors. It's probably contaminants from cleaners or grease. It's probably a leak. Blah blah blah." But I did get the name of a higher up in the organization with an email address, and I'll send an email and follow up.


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## inter (Nov 27, 2010)

try put the pads on a stove, make them hot enough to see a bit of smoke, then let them cool off.


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## BuickGN (Aug 25, 2008)

eicca said:


> So I called Shimano and of course: "It's probably cooked rotors. It's probably contaminants from cleaners or grease. It's probably a leak. Blah blah blah." But I did get the name of a higher up in the organization with an email address, and I'll send an email and follow up.


I'm not surprised. I wonder if they would change their tune if they read this thread?

My rotors are what I would call cooked. They're blued and even the non braking track is discolored all the way to the aluminum hub/spider. They still work great with resin pads which are the same pads that were on there when I got the rotors really hot. They probably get lots of calls from people that don't know any better that really do have one of the problems mentioned but this seems wide spread enough that they need to listen to the problem they're having with their pads.


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## c8stom (May 19, 2015)

I bought a brand new bike this year equipped with XTR trail brakes. On first use, the fronts bedded in nicely but the rear lacked power and squeaked. The rear rotor also discolored after an hour of riding. After a lot of reading, I decided to sand the pads and rotor and gave the entire system a cleaning with brake cleaner. After bedding in the rear, it felt as good as the front. 3 weeks of riding went by with no problems. In the 4th week, I felt a drastic loss of power in the rear with some squeaking and rotor glazing. Although I could not see any leaks, I suspected a leak somewhere.

After repeating the cleaning and daily monitoring, I discovered there was a very very small leak in the hydraulic hose where the banjo fixing is crimped to the hose. Closeup, I could see the shimmer of fluid where it should have been dry and dusty. I contacted Shimano and they gave me a new hose, new pads and fitted it under warranty. *Touch wood*, it won’t come back.

According to my LBS, many hoses were crimped poorly resulting in undetectble leaks. It would not surprise me if some of you have such a small leak it takes 2 months to contaminate your brakes. Mine took 3 weeks whether I was riding or not.

Regarding resin pads themselves, I’ve gone through a couple of sets since the leak was fixed. At no time did they glaze in use or out of use and they required no maintenance such as sanding or cleaning. I am pretty sure a leak is the primary cause of glazing.


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## eicca (May 9, 2014)

c8stom said:


> I am pretty sure a leak is the primary cause of glazing.


Been over this already and it's definitely not.


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## ColinL (Feb 9, 2012)

^^ Yep, numerous folks in this thread have no leaks and yet still have the issue.


I got the Galfer pads for my wife's bike on Tuesday but I'm about to head out of town for the holiday weekend, so it'll be towards the end of the month before I can report on them.


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## eicca (May 9, 2014)

Sent Shimano a detailed email and received a call from a service supervisor yesterday. I sent him this thread and a few others plus my pictures and experiences and he agrees, something is going on. He said that while microscopic leaks can sometimes go undetected and cause similar symptoms, sanding would never recover the pads. So he's sending me a few pairs to do tests on.

I also had an epiphany. I think humidity may be the cause. When my M775s and M395s had the issue, it took a week or two for the pads to degrade, and only a mile or so to revive them and they didn't give me any more trouble. Those two brake sets sat in a shed when not used where the ventilation is pretty constant, and outside humidity is always fairly low. Utah is of course a dry state.

My M596s, on the other hand, gave me no trouble until after sitting in my college apartment for over three months. That apartment has no central ventilation, is practically sealed tight, and showering and cooking in a small space like that produces high humidity. Now those brakes can't even make it a single day of rest without fading. Sanding brings them back, like I mentioned, but I believe it's entirely possible the pads absorbed a ton of moisture and now whenever fresh pad is exposed it oxidizes much faster. If this is true, and the chemical change is because of moisture in the pad meeting air, putting them in the oven for ten or twenty minutes should burn the water out and put a stop to the problem. When I get my new pads I'll give it a try and report back.


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## c8stom (May 19, 2015)

For what its worth, I use the below on my bikes
SHIMANO G01A Resin Disc Brake Pad - Y8J79803A
SHIMANO GO3Ti Metal Disc Brake Pad - Y8J79804A

On the purchase of my bike, my buddy threw in a few free sets of the resin and metallic pads, some packaged and some loose. I stored them all loose in a non-air tight plastic parts box along with other bike bits. After 4 months and 7 months, I put on new pads with no issues. They bedded in and have been quiet since so i don't think the above pad compounds change unless they are sprayed with some sort of sealant before coming out of the factory. Note where I live the humidity ranges from 75 to 100%.

In the case of your pads, sounds like something going on.

Whatever the cause is, hope you get to the bottom of it.


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## SHowley2003 (Feb 21, 2008)

Eicca. Thanks for taking the time to reach out to Shimano. Based on my experience I agree that it is some level of oxidation (either in the pads, or on the rotors which is then contaminating the pads when we brake). Please keep the thread updated. As I've ridden this spring I've need to clean my pads and rotors which has quieted things down a bit, though they still squeal under hard braking and I can't get back to full braking power.


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## eicca (May 9, 2014)

My moisture theory may have just died. I rode to work in the rain, 4 miles with very little braking, and suddenly they're good as new. I could barely stop when I left the garage. Maybe the water cut through the glaze somehow. 

I'm beyond perplexed now. I'm going to take them out at let them sit and watch them for a few days.

In fact if anyone is currently still dealing with the issue, see if pouring water all over the caliper and then riding makes any difference. Take a bottle with you and douse it frequently.


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## Prophet Julio (May 8, 2008)

I have ridden in the rain plenty of times. It's not moisture, but if they sit for a while, something changes. I think it's an organic growth of a fungus or slime or algae. It gets cooked off with use. I have not had to sand my brakes, just use them and they come back to life. But if I use my bike more than a couple of times a week, it doesn't happen.


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## BuickGN (Aug 25, 2008)

eicca said:


> My moisture theory may have just died. I rode to work in the rain, 4 miles with very little braking, and suddenly they're good as new. I could barely stop when I left the garage. Maybe the water cut through the glaze somehow.
> 
> I'm beyond perplexed now. I'm going to take them out at let them sit and watch them for a few days.
> 
> In fact if anyone is currently still dealing with the issue, see if pouring water all over the caliper and then riding makes any difference. Take a bottle with you and douse it frequently.


I'll definitely try that next time I go out which might be this afternoon.


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## will 6.6 (Feb 1, 2007)

I have had the same issues as well, if my bike goes unused for more than 2 days I get horrible squealing and no power. All I have to do to get power back is drag them lightly for 5-8 50m runs, then put water over calipers and a further 3-5 high speed stops, I have used original pads, and nuke proof (sintered & organic). I never sanded pads/rotors, and not cleaned rotors, again can't see any sort or leak, and every thing looks dry after left standing for a while. 
It's really a strange phenomenon defiantly not ideal, and a PITA, but once sorted I have no issues, and am really happy with the performance/feel. 
Unfortunately I have just bust my clavicle badly, surgery to follow, so I guess I will be following my above procedure when I get back on bike in 4-6 weeks. Will keep following this, hopefully some one has a eureka moment and let's every one know!!!


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## BuickGN (Aug 25, 2008)

will 6.6 said:


> I have had the same issues as well, if my bike goes unused for more than 2 days I get horrible squealing and no power. All I have to do to get power back is drag them lightly for 5-8 50m runs, then put water over calipers and a further 3-5 high speed stops, I have used original pads, and nuke proof (sintered & organic). I never sanded pads/rotors, and not cleaned rotors, again can't see any sort or leak, and every thing looks dry after left standing for a while.
> It's really a strange phenomenon defiantly not ideal, and a PITA, but once sorted I have no issues, and am really happy with the performance/feel.
> Unfortunately I have just bust my clavicle badly, surgery to follow, so I guess I will be following my above procedure when I get back on bike in 4-6 weeks. Will keep following this, hopefully some one has a eureka moment and let's every one know!!!


I think you're the first to have this problem with aftermarket pads, at least that I can remember. Are you absolutely sure there's no fluid leakage and do both brakes have the same problem?

Do you have Icetech rotors?


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## will 6.6 (Feb 1, 2007)

Running icetech rotors and same issue on both front/rear, I was out in Cyprus for a while v dusty so any minor leak would show up? A few times I have given a calipers a v good clean, stripped down, cotton buds out, then left for afew days no sign at all of leakage, but squeal/loss of power still occurred. Plus I have never sanded/baked/cleaned pads to get power back, just do the above mentioned ritual, wouldn't contamination require that or replacement pads. In UK now, and loss of power happens in a shorter period of time, I think. 
Once I get them "burned in" they are back to original power, and I am v happy with performance. 
I am going to keep a better tab on what I do, I think that after I have used v aggressive they go off quicker than after a lighter use. Might also swap over spare hope rotor, and see if that makes any difference


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## matto6 (Dec 28, 2013)

Last time I fixed them by sanding. This time I tried just cooking them by braking hard, and it worked. 

I used a section of road with a steep hill, got momentum then braked hard. Repeated 4 times and fixed.


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## Aglo (Dec 16, 2014)

Hi,

Out of curiosity, I have been following this thread, because I have XT brakes and never had this problem, or at least I never noticed this problem.
I have XT brakes with finned metallic pads. My front rotor is an IceTech SM-RT86 203mm and my rear rotor is a standard SM-RT56 180mm. My winter season is very rainy and muddy and my summer season is dry and dusty.
I ride in rainy days, cold days, foggy days or all the above at once. Some times I leave my bike in the garage without washing it first and my calipers stay wet and covered in mud until the next ride, that could be in the next day or 5 weeks later.
My garage is underground, meaning it is always cold and in the winter can be a little humid.
As I said before, I never had this problem, so if you want to ask anything about my brakes to compare with yours, just ask.


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## c8stom (May 19, 2015)

May I suggest someone who has this problem try the following ; before you park the bike for a few days or weeks, remove both sets of pads and place one set near the bike but exposed. Place the other set in an air tight container. The next time you ride, inspect the rotors for anything unusual and clean if necessary. Then put both sets of pads back on and let us know if they squeal.


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## Cleared2land (Aug 31, 2012)

^^^ No one should have to do this.


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## newtrout (Jul 7, 2009)

I think he is suggesting it for the sake of identifying the problem, not proposing it as a solution..


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## BuickGN (Aug 25, 2008)

Aglo said:


> Hi,
> 
> Out of curiosity, I have been following this thread, because I have XT brakes and never had this problem, or at least I never noticed this problem.
> I have XT brakes with finned metallic pads. My front rotor is an IceTech SM-RT86 203mm and my rear rotor is a standard SM-RT56 180mm. My winter season is very rainy and muddy and my summer season is dry and dusty.
> ...


I think this is the most telling post here. It eliminates environmental factors and rotor type. I was really beginning to think the stainless/aluminum sandwich combined with the metals in the pads were having some kind of reaction.

I truly think it's an issue with pads only. Maybe environmental factors can speed up the process but then again I only had under 24hrs till mine lost all power and I live in a dry area and keep the bike inside.

The only question I have is have your pads ever gotten good and hot? That seems to be what started the problems with both sets of mine.


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## Cleared2land (Aug 31, 2012)

c8stom said:


> May I suggest someone who has this problem try the following ; before you park the bike for a few days or weeks, remove both sets of pads and place one set near the bike but exposed. Place the other set in an air tight container. The next time you ride, inspect the rotors for anything unusual and clean if necessary. Then put both sets of pads back on and let us know if they squeal.





Cleared2land said:


> ^^^ No one should have to do this.





newtrout said:


> I think he is suggesting it for the sake of identifying the problem, not proposing it as a solution..


That's correct...that's how I indentured it.

To restate my meaning...it's ashamed that we have to go through this to identify a problem.


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## BuickGN (Aug 25, 2008)

Cleared2land said:


> That's correct...that's how I indentured it.
> 
> To restate my meaning...it's ashamed that we have to go through this to identify a problem.


I agree but it looks like Shimano might try chalking it up to dumb consumers over looking obvious problems and not their pads. Hopefully they realize there's a legit problem with their pads that's not caused by contamination or environmental factors.

In the beginning my problem wasn't bad enough to complain about. Most sintered pads don't grab too well until they have a small amount of heat into them, usually during the first stop they come up to full power. My Trance is used for everything including a ride around the neighborhood or at the park with the fiancée and the dog. The brakes got so bad that they would never get to even acceptable power to the point I almost ran over my dog when he walked in front of me. I ended up putting my feet down to stop because that was much more effective than the brakes were. Then the problem eventually started on my new XTs on the Epic which also now has resin pads with great results.


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## Aglo (Dec 16, 2014)

BuickGN said:


> (...)
> The only question I have is have your pads ever gotten good and hot? That seems to be what started the problems with both sets of mine.


In some long and steep descents on fire roads with loose gravel, I have to drag the front brake. So they get really hot, but I never blued a rotor. Neither Icetech nor normal.


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## c8stom (May 19, 2015)

BuickGN said:


> I agree but it looks like Shimano might try chalking it up to dumb consumers over looking obvious problems and not their pads. Hopefully they realize there's a legit problem with their pads that's not caused by contamination or environmental factors.


We just need one person with the issue to scrape some convincing evidence together and to bring it to Shimano's attention. In my experience, Shimano ( Asia ) has always been responsive and reasonable when presented with decent evidence.

That said, I think it will be near impossible to prove a given set of Shimano pads are defective without performing tests on a few identical sets in controlled conditions. Sadly, the onus falls on the poor consumer as Shimano are well aware there are thousands/millions of pads out there that do not have these issues.

I believe one user in this thread has already contacted Shimano but I am not sure if there was a response ?.

When my defective banjo on my new bike leaked and contaminated my pads, I was also given new pads along with cables by Shimano because my LBS confirmed my pads were damaged as a result of the defective banjo. If my LBS did not confirm this, I would have only received replacement cables under warranty and would have had to fork out for a new set of pads despite the bike being new. It appears Shimano's policy on replacement pads is extremely strict / brutal.

I suggest those affected try contacting Shimano as they may respond favourably. Afterall, pads are cheap and will not dent the balance sheet if they have give out a few hundred sets for free... Goodluck


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## rfxc (Oct 18, 2004)

I started this thread, and still experience this problem on occasion. I also use a few truckerco pads, which are NOT immune to this problem. I've changed rotors, avid, shimano pre-icetech, and ictech rotors... Still happens occasionally when a bike sits idle for 6-8 weeks.


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## Cleared2land (Aug 31, 2012)

Perhaps the best fix is to NOT sit idle. 

Get on your bike and ride.


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## c8stom (May 19, 2015)

rfxc said:


> I started this thread, and still experience this problem on occasion. I also use a few truckerco pads, which are NOT immune to this problem. I've changed rotors, avid, shimano pre-icetech, and ictech rotors... Still happens occasionally when a bike sits idle for 6-8 weeks.


Have you changed the caliper at all ?


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## eicca (May 9, 2014)

I took off the pairs that are giving me trouble, labeled them, sanded them, and I'm letting them sit inside the Shimano plastic packaging that pads come in. If experiences hold true, I should see the gold surface fade to that grey glaze in a few days. I'm taking pictures of every step. 

Meanwhile, I installed the metallic pads Shimano sent me and went on a good ride aside from my usual work commute. 1) They modulate and stop waaaaay better than the resins and 2) they haven't given me any idle-fading trouble. Yet.


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## c8stom (May 19, 2015)

eicca said:


> I took off the pairs that are giving me trouble, labeled them, sanded them, and I'm letting them sit inside the Shimano plastic packaging that pads come in. If experiences hold true, I should see the gold surface fade to that grey glaze in a few days. I'm taking pictures of every step.
> 
> Meanwhile, I installed the metallic pads Shimano sent me and went on a good ride aside from my usual work commute. 1) They modulate and stop waaaaay better than the resins and 2) they haven't given me any idle-fading trouble. Yet.


Good stuff.... Does the gold surface contain brass ? I believe brass is quite stable so it must be something else causing the fading. Post some pics later and happy braking the meantime


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## ColinL (Feb 9, 2012)

eicca said:


> I took off the pairs that are giving me trouble, labeled them, sanded them, and I'm letting them sit inside the Shimano plastic packaging that pads come in. If experiences hold true, I should see the gold surface fade to that grey glaze in a few days. I'm taking pictures of every step.


Interesting experiment! I had wondered if it's not only the pad, but proximity to the stainless steel rotor. Bi-metallic corrosion, perhaps.


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## oweya (Sep 15, 2005)

I have resin pads on my 2014 XT brakes and they have howled since day one. Sanding the pads and even the rotors did nothing, rubbing alcohol and degreaser were fruitless as well. Eventually the pads got quieter as I rode through the summer but the sound never fully went away. 

Started riding again this spring and the sound was way worse. I then hit the pads with a propane torch for about 30secs each causing them to briefly catch on fire (1-2secs). Since then my brakes have been silent with better power.


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## BuickGN (Aug 25, 2008)

oweya said:


> I have resin pads on my 2014 XT brakes and they have howled since day one. Sanding the pads and even the rotors did nothing, rubbing alcohol and degreaser were fruitless as well. Eventually the pads got quieter as I rode through the summer but the sound never fully went away.
> 
> Started riding again this spring and the sound was way worse. I then hit the pads with a propane torch for about 30secs each causing them to briefly catch on fire (1-2secs). Since then my brakes have been silent with better power.


That sounds like fluid contamination.


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## ColinL (Feb 9, 2012)

Wife's bike with XT M-785 brakes is working extremely well with Galfer FD452 pads. She does not have any leaks - if you do, obviously that needs to be resolved first, because any leaking at the caliper will ruin any pad.

I got them here: Galfer 1053 Standard Shimano Brake Pads > Components > Drivetrain, Brakes and Pedals > Brake Pads | Jenson USA

Installed pads, verified rotor clearance, cleaned both rotors with a lint-free rag and rubbing alcohol. Then I bedded in both brakes. Tons of power and no noise. They've been fine for over a week so far but I'm not willing to call it 100% good just yet. I'd like to get a month down the road to be sure.


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## jonshonda (Apr 21, 2011)

Interesting story regarding this issue. At my LBS shooting the sh!t w/ a local rider who has/had a LOT of bikes. He has had nothing but problems with Shimano brakes, and owns many different brands (so I assume he is not a ham fisted dork). His issues mirror what many others have said in this thread EXACTLY. 

I commented that I have not had any issue with my cheapy deore brakes and Ice Tech rotors. WELL, WOULDN'T YOU KNOW ON THE VERY NEXT F'IN RIDE my rear brake started acting up. Pull the lever, next to no power (friction), then when the power does come on (maybe 50%) they let out a AVID BANSHEE scream!!

Looks like it is time for a pad sanding fest, then onto maybe some new pads or Hopes.


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## dvzzz (Apr 27, 2011)

I had both Deore and XT squeal until I baked them for 1 hour at 350 degrees. My calipers had not leaks so it was something with resin pads that was causing it. After baking, brakes were great. I will have to bake them at the beginning of each season but at least I know the reason for it.



jonshonda said:


> Interesting story regarding this issue. At my LBS shooting the sh!t w/ a local rider who has/had a LOT of bikes. He has had nothing but problems with Shimano brakes, and owns many different brands (so I assume he is not a ham fisted dork). His issues mirror what many others have said in this thread EXACTLY.
> 
> I commented that I have not had any issue with my cheapy deore brakes and Ice Tech rotors. WELL, WOULDN'T YOU KNOW ON THE VERY NEXT F'IN RIDE my rear brake started acting up. Pull the lever, next to no power (friction), then when the power does come on (maybe 50%) they let out a AVID BANSHEE scream!!
> 
> Looks like it is time for a pad sanding fest, then onto maybe some new pads or Hopes.


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## c8stom (May 19, 2015)

jonshonda said:


> Interesting story regarding this issue. At my LBS shooting the sh!t w/ a local rider who has/had a LOT of bikes. He has had nothing but problems with Shimano brakes, and owns many different brands (so I assume he is not a ham fisted dork). His issues mirror what many others have said in this thread EXACTLY.
> 
> I commented that I have not had any issue with my cheapy deore brakes and Ice Tech rotors. WELL, WOULDN'T YOU KNOW ON THE VERY NEXT F'IN RIDE my rear brake started acting up. Pull the lever, next to no power (friction), then when the power does come on (maybe 50%) they let out a AVID BANSHEE scream!!
> 
> Looks like it is time for a pad sanding fest, then onto maybe some new pads or Hopes.


Stay cool man. Rip those pads out, douse them in any flammable liquid of your choice and set them on fire. Then call shimano and give them an earful. By the time you're done on the phone, pads will be ready to go back into the calipers if they've not completely incinerated. You should then feel better, perhaps.


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## jonshonda (Apr 21, 2011)

^Haha!

I went for a pretty hard ride last night and the rear brakes came back to life w/o the need for FIRE!! I will follow up if I continue to have issues.


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## Marc2211 (Aug 6, 2013)

I installed a new set of Shimano Zee brakes on my Slash in Feb this year after my Avid Elixir 5's suddenly gave up (again). I retained my Avid 200mm rotors as I'd just replaced them. 

Not had any issues at all for the last 4 months - Great power, modulation until I left my bike for 3 weeks without riding it this month (I was riding another for my commute). 

I tried the bike last night as I felt like a quick trail blast - no brake power, squealing and very bad modulation. 

It has sat in my basement in a controlled temp environment, without sunlight etc so have no clue what has caused this.


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## torete43 (Jul 16, 2014)

Same issue here. I've read the hole thread with hope, but no real fix yet. This is driving me crazy. My problem is exactly as described here: terrible squealing and power loss after sitting the bike for a few days. M785 brakes with RT81 IceTech rotors and finned F01A resin pads (although same issue happened with F03C metal pads). Just to add some more intrigue, it is only happening with my rear brake, front brake works great with the same components. I tried everything, replacing rotors, pads, cleaning, bleeding, sanding everything, etc. I cannot see any leaking, so unless it is microscopic, there is no reasonable explanation for this.

I can't believe the pads just get glazed magically just by doing nothing. Although I store the bike in a terrace partially outdoor close to the sea (humidity and salty air) I discarded the environmental theory as my front brake works like a charm. There must be something else....



Enviado desde mi SM-N9005 mediante Tapatalk


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## TJay74 (Sep 26, 2012)

So I am in the boat as well with my 2014 XT brakes and my wifes 2014 SLX brakes. Pads are shot if left sitting for longer than 2 months. First time the shop blamed it on me that I contaminated the pads somehow. So I sprung for new pads for both bikes.

Next time my bike did it, once again shop said it was me or the brakes have a leak, once again I put new pads on it. I went thru the system thoroughly and there were no leaks at all, I wiped the entire caliper down with brake cleaner from top to bottom. Put new pads in and got 3 rides on them before I parked the bike. We don't do much summer riding here in Oklahoma, not much of any trail maintenance and the trails get over grown with poison ivy and ticks.

Pulled the bike down 2 weeks ago and once again pad squeal and no power. I had some parts in the over so I went to test moisture contamination theory. Baked the pads at 300° for two hours. Then removed them and lightly sanded the glazing off. Re-bedded the pads and back to normal. All of these sets of pads have been resin.

Called Shimano, the tech said it is an issue with resin pads. Said take it to the dealer since the XT stuff is under 2 year warranty. Took it to my LBS, Shimano tech told them he had never heard of moisture contamination. He ran the mechanic thru all sorts of tests and check, finally came back and said it is an issue with the caliper that Shimano knows about. Said it is leaking slightly causing the issue. They are sending me new calipers and pads for both ends.

Now the sad part to the story, another mechanic told me he has 2 customers going thru the same thing, but system is out of warranty. Shimano told him the same thing, bad calipers. Now here is the crappy part, if you are out of warranty Shimano does not offer a parts rebuild kit nor do they offer the caliper by itself. Only option was to buy a whole new system.

So if you are under warranty Shimano will take care of it, if you are not then you get to pound sand. So one of my bikes is covered and I have to eat an entire system on my wifes bike or else replace the pads again.

Also you want to know what Shimano's suggestion is to stop the issue, remove the pads when the bike is not in use and store them in a plastic baggy. 

Nice Shimano, real nice....


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## eicca (May 9, 2014)

I think SRAM Guides will be my next brake purchase.

TJay74, did baking the resin pads prevent them from losing power when sitting? I was going to try that with my set I have sitting around.


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## TJay74 (Sep 26, 2012)

on the short test rides in my neighborhood it seemed to have corrected the issue. Power came back and no squealing at all.


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## aerius (Nov 20, 2010)

And now it gets interesting. Friend of mine bought a set of Saint brakes (H03C pads) which had the same power loss issue as the ones I have, his pads were going bad on him overnight. He was dealing with it the same way I was, sand them before each weekend trip to the local the bike park. Recently, he went on a trip to Mont Saint Anne for a week and did a ton of runs on the world cup course and other DH trails. After a few days of riding there, his brakes were cured and he didn't need to sand them anymore. It seems the long DH runs and heavy braking put enough heat into the pads to bake them in and fix them, and a week later they remain fixed.

So I gave my own H03C pads a quick sanding, put them in the toaster oven and baked them at 450F for 15 minutes, then left them in there for a half hour or so to cool down. I did a short ride to bed them back in and then let them sit for a couple days, which was enough to make them go bad in the past. This time, they stayed working. Full power, no noise, good as new. Hopefully, this is a permanent fix, but to be sure I'll have to pull the pads and let them sit for a couple weeks. We'll see what happens next month, but fingers crossed, it looks like there's a cure for the finned metallic pads.


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## torete43 (Jul 16, 2014)

This is crazy. I tried with a different set of pads, Shimano Aluminium G01A (Resin) a few days ago. I just sand them a bit along with the IceTech disc just to remove any contaminated residue and sit the bike in the terrace covered with its BikeParka. Today guess what .... same noise again. I didn't even ride the bike. Who the hell can explain what is happening? Everything points out to some kind of micro-leaking (whatever pads you put there, they got ruined). However, if that is the real issue, I should see something by inspection or I should notice a change in the brake lever pressure (leading me to add some oil to the system from time to time). But this is not the case.

I decided today to cook my pads, it's worth a try. I used a lighter and let them on fire a couple of minutes intermittently. After sanding them a bit, the surface looked best than ever and its typical gray color with traces of golden/copper metal came to life. A few rides in the street and the brake works better than new, with full power and a lot of bite. Lets see if that remains much more of a mirage than a real fix ...


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## LCW (May 5, 2008)

The baking process definitely works for the Shimano metallic pads. Did it with my Saint H03C pads. Basically had to since they got contaminated with mineral oil from a messy bleed.

Baked them @ 400F for about 1 hr. Sanded them first. Also cleaned the rotors with brake kleen. Reassembled and proceeded to bed them in. After a few stops - as good if not better than new!! Definitely worth a try especially if your pads have lots of life left in them.

My bike sits often for 1-2 weeks at a time without riding. Never had the "power loss" issue. But in a high moisture environment, with metallic pads, I could see that happening. Baking seems to work!


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## aerius (Nov 20, 2010)

And an update. I believe there's now a permanent fix for the finned metallic pads which are suffering from the squeal & power loss issue. The short version is clean them, give them a quick sanding, then bake them in a toaster oven at 450°F for 15-20 minutes and let them cool. I did this to my problem sets of pads about 2 weeks ago, rode them, put them away, and today they are still working properly. Success at last! Before this they'd always go bad again within a couple days.

The longer version is I've had 2 sets of H03C pads which came with my Zee brakes that for whatever reason lost all power and squealed like mad when I let them sit unused for a couple days. All my other sets of pads worked perfectly fine with no issues whatsoever in the same brakes, so by process of elimination it was confirmed as a pad problem specific to those 2 sets of pads. I tried various other fixes such as cleaning with alcohol, sanding, and so forth, but nothing ever stayed fixed for more than couple days, the squeal and power loss always came back. A quick sanding would bring the power back but once the bike was ridden & put away the problems would return.

I resigned myself to weekly sanding of the pads before bike park or cottage days, and used my non-finned sets of pads for everyday riding. That was, until my friend's pads which were suffering the same issues as my own fixed themselves while he was on vacation at Mont Sainte Anne, it appears the long DH runs and heavy braking baked his pads in and fixed whatever was wrong with them. So I gave my sets a good hot bake in my toaster oven and they're now fixed as well. And they've stayed fixed for 2 weeks and counting, which is about 10 times longer than all previous fixes.


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## torete43 (Jul 16, 2014)

Yeaaaahhh! Success for me as well. It seems that baking process works. I literally burnt my resin pads with a lighter for a couple of mintues. I did it with 2 sets, Shimano F01A and Shimano G01A (aluminium plate, not finned). I can confirm G01A works great with the baking, at least no more issues in about 2 weeks. I had to try with the finned F01A just to confirm this fix is reliable.


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## eicca (May 9, 2014)

I desperately need to try this with my own and send the results back to that Shimano rep.


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## RWGreen (Dec 5, 2004)

Interesting to see this thread as I was researching potential new brakes... I had this issue with XTR brakes a couple years ago and never resolved it, just replaced with hopes and moved on. Was hoping that someone would have solved this by now. Will be following this... was interested in the new black XT m8000


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## kryten (Mar 8, 2012)

Tired of having the same issues with my brakes. Sanded them down and baked them for 15 min at 425F. Cleaned the rotor with 99% IPA, but ran out of time to bed them in. Will do so today and report in a week or two how things are.

XT 785 brakes
F01A Resin finned XT pads
RT56 rotors 180/160

Left is before and right after sanding with 60 grit paper.


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## jonshonda (Apr 21, 2011)

I posted a few months back that a I had good results with trying to "rebed" the pads on my Deore brakes (which I imagine come with the cheapest sh!t pads known to man). Well, the results were temporary, and now I am back to a lack of power and lots of noise. Time to dump some dump some denatured alcohol on them and let my torch have its way with them for a while.


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## BuickGN (Aug 25, 2008)

Deores use the same pads as the rest of Shimanos 2 piston lineup. Rebedding is only temporary. You need to bake them or torch them and then sand them lightly for a few seconds. Those look like fluid contamination. From what I've seen, fluid contamination causes a loss of power along with noise. The overnight issue that we believe is oxidation is just a loss of power with no noise.


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## kryten (Mar 8, 2012)

BuickGN said:


> Deores use the same pads as the rest of Shimanos 2 piston lineup. Rebedding is only temporary. You need to bake them or torch them and then sand them lightly for a few seconds. *Those look like fluid contamination.* From what I've seen, fluid contamination causes a loss of power along with noise. The overnight issue that we believe is oxidation is just a loss of power with no noise.


Were you commenting one the latest picture above? I don't have any noises, they just loose power after a few days. I was barely able to lock up my rear wheel last time. Either way, it is done now, they are sanded and baked so will see what happens next.


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## Ride-beer-rinse-repeat (Mar 26, 2009)

Glad I stumbled into this thread - I have been having many of the same issues! I'll try some of the ideas here and report back.

My bikes are stored in a shed, so warm and humid all summer here in SC.

My SS (XTR trail finned pads) sat for a few weeks while I rode another bike and it immediately had a loud front brake and then lost most of the front braking even though the noise quit (after around 20 medium to hard braking cycles) I'll begin with the bake/sand pads and clean rotor and see how that works. Fingers crossed....


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## kryten (Mar 8, 2012)

kryten said:


> Tired of having the same issues with my brakes. Sanded them down and baked them for 15 min at 425F. Cleaned the rotor with 99% IPA, but ran out of time to bed them in. Will do so today and report in a week or two how things are.
> 
> XT 785 brakes
> F01A Resin finned XT pads
> ...


So I took my bike out for a 45 min ride and the front brake has decent power and bite and stayed working reliably for the whole ride, rear brake definitely has some issues. I can still lock up my rear wheel, but the whole power/feel is not very confidence inspiring. Half way through my ride, rear brake started squealing and lost even more power and feel so that I could barely lock up my rear wheel. Pretty sure pads are contaminated again and my caliper has a small leak.

It was dark, so I will inspect caliper/lever for leaks this weekend when I get a chance and will report back. I'm pretty much certain it is not leaking at the lever, so it will be caliper leak.

I guess I'm looking for something like this:






I'm fairly confident that this is my issue now, and once confirmed, I'm leaning to replacing at least my rear brake for now with Zee instead of getting a new XT caliper. My understanding is Shimano does not offer rebuild kit and these came on a used bike so I have no way of claiming warranty with Shimano.


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## TJay74 (Sep 26, 2012)

Both my bike and my wifes bike got new calipers (mine XT with metal pads, her SLXwith resin). I took my bike and bedded in the pads and did 3 rides (maybe 60 miles) and then the bike sat for 2 weeks. My wifes bike got bedded in with maybe a 10 mile ride.

I pulled both bikes down and both have lost all braking power and squeal horribly. I have sanded and cleaned with alcohol on both. LBS called Shimano last week who wanted to throw more parts, LBS said no and demanded whole new setup. Shimano is sending me new XT M8000 full brake systems, wifes bike goes back in next week after mine is fixed to make the same demands on her bike.

This is getting out of control, if Shimano knows there are issues they need to do something and ASAP. I can promise if my wife or I get hurt because we cant stop that this thread and all of our service records along with Shimano's warranty process will be the first thing I hand over to a personal injury lawyer.


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## TheGweed (Jan 30, 2010)

2016 XT brakes here..the black ones with finned metallic pads. Had them for a couple weeks, no issues. Bike was muddy so I hosed it down at the trailhead and wiped it down last Sunday. Had a loud squeal from the front, but nothing from the back. Bike sat for the week until today...brakes were silent and great again. 

I switched from Elixir 5's so I hope this will be the norm.


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## TJay74 (Sep 26, 2012)

It is normal for the brakes to squeal after washing.


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## TJay74 (Sep 26, 2012)

So the shop got the new XT 8000 brakes installed for me under warranty from Shimano. Just need to find some time to test them out and see how they do.


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## jonshonda (Apr 21, 2011)

So I had some time to work on the bike and pulled the pads, soaked them in Alcohol and torched them. Then while they were still hot I sanded them. First ride was much better with no squealing and much better pad grip.


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## BuickGN (Aug 25, 2008)

My resin pads did this for the first time, only the rear. The bike has sat for 2 weeks now. I got tired of just looking at it so I took it through the neighborhood last night and had virtually no rear brake, just noise. These are Zees with finned resin pads. The front was perfect. I think I found the culprit. I remember catching my Golden Retriever licking the rear rotor about a week ago. I'm betting that's the cause. He's trying to kill me.


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## jonshonda (Apr 21, 2011)

BuickGN said:


> I think I found the culprit. I remember catching my Golden Retriever licking the rear rotor about a week ago. I'm betting that's the cause. He's trying to kill me.


He's a contract killer! Better watch your back, and your peanut butter.


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## NordieBoy (Sep 26, 2004)

Got the big squeal from the rear in the last lap of the XC race on Sunday. Finned pads, resin front, sintered rear. No water on the course, just a bit dusty.


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## mjiman (Nov 28, 2005)

For those of you with squeaky XT/XTR disc brakes I learned today that heating the pads is a necessary step. I have the resin pads with icetech rotors. I heated the pads with direct flame from a mini butane torch. As I heated the pads I saw small sparks of material burning off-as I heated there was less and less material burning off. I stopped heating once the burn off subsided. I assume the material burning is the contaminant but it did the trick. The brakes also had a lot more power after heating them. Before heating the pads I cleaned the rotors and pads with alcohol and sanded the rotors and pads very thoroughly. After this I still had squeaky brakes and the power was poor. You would think Shimano could explain this issue-this has happened to me for years and I have discarded many a good brake pad.


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## Rmplstlskn (Sep 18, 2015)

Could this issue be related to IceTech rotors? Leaving material deposits on pads...

I ask because my metal-pad M8000 front brake with IceTech rotor does not sequel, but it lacks braking GRIP... But the rear metal=pad M8000 with a "resin-only" rotor seems to stop very well.

Rmpl


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## eicca (May 9, 2014)

Rmplstlskn said:


> Could this issue be related to IceTech rotors? Leaving material deposits on pads...
> 
> I ask because my metal-pad M8000 front brake with IceTech rotor does not sequel, but it lacks braking GRIP... But the rear metal=pad M8000 with a "resin-only" rotor seems to stop very well.
> 
> Rmpl


It's definitely pad-only. I've had it happen on "resin-only" rotors and some nice Alligator-brand ones too.


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## Cleared2land (Aug 31, 2012)

^^^ I fully agree. It's the pads. I was amazed at how well a propane torch 'cooked' the problem. That five minute fix, worked great.


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## rfxc (Oct 18, 2004)

I've had over 6 sets of 985/785 series shimano brakes with this problem, as I described in the OP. Resin pads, metallic pads, finned and not, shimano and truckerco-- all have had the issue I originally described if the bike sits for a long period of time. The SAME pads sit in my commuter bike with TRP spyre mechanical brakes and DO NOT have this issue after sitting. The best theory in this thread is that mineral oil very slowly seeps around the pistons and contaminates pads. When bikes are used very regularly, small amounts of oil burn off quick. When they sit, more oil seeps out and contaminates the pads beyond what my local hills allow me to burn off effectively. So I've gotten accustomed to sanding and burning with a propane torch. :/

I also have a bike with M9020 brakes now for 6 mos, and have NOT had this issue with them. The caliper is different, and the piston looks different compared to the older 785/985/980 series. The M8000 calipers look different as well (in photos)... and I have to wonder if a different/newer caliper piston/seal design has been deployed to prevent this issue in the newer M9020 and M8000 brakes. I'd like to start selling off my (and my wife's) old 985/785 sets and replace with M8000 brakes... but can anyone confirm or validate this notion?


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## Cleared2land (Aug 31, 2012)

rfxc said:


> The best theory in this thread is that mineral oil very slowly seeps around the pistons and contaminates pads. When bikes are used very regularly, small amounts of oil burn off quick. When they sit, more oil seeps out and contaminates the pads beyond what my local hills allow me to burn off effectively.
> 
> ... but can anyone confirm or validate this notion?


I'm not subscribing to this theory.

I have experienced the same brake related issues in the past and to better define why I disagree (at least in my case) is that I frequently ride on very talcum like trails that place a fine coat on everything. If you have ever seen a talcum like powder around even the slightest oil leak, it appears very obviously that there's a leak or seepage present. After removing brake pads on multiple occasions, I have never seen even the slightest indication of seepage near caliper pistons, seals or banjo fittings.

I can't explain what the origin of the problem is, but I don't believe it's seepage of brake fluid.


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## spyghost (Oct 30, 2012)

here's what i experience for m8000, stock resin finned pads, stock hose, bh90-sbm.

front brake
1 - no howling even if left idle
2 - instant stop
3 - free stroke adjusted all the way in, 20mm lever movement before pad engages

rear brake
1 - howls after a week without use but goes away after a few heavy dh braking
2 - had to apply a little more pull compared to front for instant stop
3 - free stroke adjusted all the way in, 25mm lever movement before pad engages

i don't see any leakages of any sort for the rear brake, the hose, and the lever... it remains bone dry all throughout. i inspected it with the pads removed and off the frame.

1 - any ideas why the rear brake operates differently?
2 - how much do your levers move with the free stroke screw all the way in?


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## aerius (Nov 20, 2010)

rfxc said:


> I've had over 6 sets of 985/785 series shimano brakes with this problem, as I described in the OP. Resin pads, metallic pads, finned and not, shimano and truckerco-- all have had the issue I originally described if the bike sits for a long period of time. The SAME pads sit in my commuter bike with TRP spyre mechanical brakes and DO NOT have this issue after sitting. The best theory in this thread is that mineral oil very slowly seeps around the pistons and contaminates pads. When bikes are used very regularly, small amounts of oil burn off quick. When they sit, more oil seeps out and contaminates the pads beyond what my local hills allow me to burn off effectively. So I've gotten accustomed to sanding and burning with a propane torch. :/


In your case it's almost certainly a slow leak, and yes, I have seen a few cases of SLX and XT calipers leaking oil from the o-ring area which joins the caliper halves. If the same pads which are going bad in your Shimano brakes are working fine in another set of brakes, then the problem is in the caliper.

However, in my case and quite a few others, we have pads that go bad and pads which don't go bad, all in the same caliper. In my Zees for instance, I had a set of H03C pads that went bad overnight, an older set of H03C pads that stayed working even if I let it sit for weeks, and a set of D02S pads that also stayed good. Same caliper, same rotors, same everything except the pads. So in my case it's clearly a pad issue.


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## eicca (May 9, 2014)

I talked to the Shimano rep over the phone about the exact same thing. He says he thought at first it would be a microscopic oil leak, but if that were true, sanding the pads would not bring them back to life like it did in my case.


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## Cleared2land (Aug 31, 2012)

Agreed, you can't sand away oil residue. 

I believe that it's some form of oxidation if it can be mechanically removed. But that doesn't explain how torching the pads works either.


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## gmcttr (Oct 7, 2006)

spyghost said:


> ...1 - any ideas why the rear brake operates differently?...


The longer hose to the rear brake allows for more expansion than the short front hose causing rear brakes to have a slightly softer feel.

Assuming no rear brake contamination from the increased amount of crap thrown onto them, it's likely that the front and rear have the same potential to make noise. The rear brake noise may well be a function of the difference between the frame/swingarm harmonics compared to the front fork.


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## Cleared2land (Aug 31, 2012)

gmcttr said:


> The longer hose to the rear brake allows for more expansion than the short front hose causing rear brakes to have a slightly softer feel.


This assumption is entirely negligible and wouldn't be discernible to the rider. The master cylinder is not capable of providing enough pressure to overcome the brake line design expansion limits.


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## ziscwg (May 18, 2007)

Cleared2land said:


> Agreed, you can't sand away oil residue.
> 
> I believe that it's some form of oxidation if it can be mechanically removed. *But that doesn't explain how torching the pads works either.*


Actually it does, heating the pads changes whatever is oxidizing so that it cannot anymore. The heat likely forces all the oxidation to occur at once. Then, you sand the pad and you don't get anymore oxidation.


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## eicca (May 9, 2014)

I agree with the sentiment that longer brake hoses expand more because every single brake I've ever touched has felt softer in the back, regardless of brand, even after a fresh bleed, etc.


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## spyghost (Oct 30, 2012)

Im not totally convinced by the longer hose, softer feel theory. I got a non-series shimano hydro and it didn't feel like this


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## Aglo (Dec 16, 2014)

spyghost said:


> Im not totally convinced by the longer hose, softer feel theory. I got a non-series shimano hydro and it didn't feel like this


Maybe your front brake was softer than it should.
Except the hose length everything is equal between front and rear, and unless you are using solid metal lines, the hoses will expand, and the bigger the hoses the more you feel this expansion, and you can add the fluid compression too, but that is negligible compared to the hose expansion.
Don't forget that the hoses are just a plastics tube, a good and special plastic tube, but a plastic tube nevertheless.


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## spyghost (Oct 30, 2012)

From this thread: https://forums.mtbr.com/brake-time/xt-brake-swap-question-936915.html#post11547609

Looking at this pic in particular:









There's still a bit of hose showing up between the olive and the barb. I took off mine and noticed that I don't have any 'gaps' between the compressed olive and barb fitting (ie only the silver barb is showing up, no black hose in between)...

I don't have any fluids leaking from the threads though, but could it be that there's a gap between the lever and the barb fitting that traps air, which is nearly impossible to remove no matter how the lever is positioned? No hose showing between the olive and the barb could mean that the flat sides of the barb and the lever aren't contacting at all...

if that were the case, can i just cut off the olive and replace it with a new one?


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## Cleared2land (Aug 31, 2012)

Interesting that you are using my photo from a previous thread.

That is perfectly correct. When the connection nut is being tightened the olive is pushed along the brake hose towards the master cylinder until it reaches the end and begins to crush tight to the brake line (hose). You will always have that minimal amount of black brake line on all lines.


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## spyghost (Oct 30, 2012)

Cleared2land said:


> Interesting that you are using my photo from a previous thread.
> 
> That is perfectly correct. When the connection nut is being tightened the olive is pushed along the brake hose towards the master cylinder until it reaches the end and begins to crush tight to the brake line (hose). You will always have that minimal amount of black brake line on all lines.
> 
> View attachment 1034707


thing is, i don't see any black hose between the barb and the olive that's why i'm thinking that there 'might be' a sort of 'gap' between the surface of the lever internal and the surface of the barb...

i may have incorrectly tightened the nut with the hose not fully seated against the lever internal... not sure if this is a 'possibility' though... but then, I don't get any leaks from the threads...


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## Cleared2land (Aug 31, 2012)

spyghost said:


> thing is, i don't see any black hose between the barb and the olive that's why i'm thinking that there 'might be' a sort of 'gap' between the surface of the lever internal and the surface of the barb...
> 
> i may have incorrectly tightened the nut with the hose not fully seated against the lever internal... not sure if this is a 'possibility' though...


Yes, you could be correct in stating that you might not have pushed the brake line in far enough before tightening the hose connection nut. After placing the olive on the brake hose and inserting the barbed insert, then push the hose into the master cylinder until the hose stops and has reached it's maximum depth into the master cylinder. Then begin tightening the connecting nut. I believe that when correctly executed, you will see the small part of the brake hose between the crushed olive and the barbed insert.


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## Rmplstlskn (Sep 18, 2015)

The micro-leaks around the pistons doesn't make sense... Looking at my finned M8000's, I do not see how mineral oil would defeat gravity and wick its way around the aluminum plate that holds the fins and brake material, and the brake material is on the opposite side of the pistons....

Sounding more and more like poor materials used in the brake pads, especially the metallic pads... Who knows what is compressed into that pad mixture... Maybe recycled brake material from auto brake manufacturing... Who knows...

Rmpl


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## spyghost (Oct 30, 2012)

Cleared2land said:


> Yes, you could be correct in stating that you might not have pushed the brake line in far enough before tightening the hose connection nut. After placing the olive on the brake hose and inserting the barbed insert, then push the hose into the master cylinder until the hose stops and has reached it's maximum depth into the master cylinder. Then begin tightening the connecting nut. I believe that when correctly executed, you will see the small part of the brake hose between the crushed olive and the barbed insert.
> 
> View attachment 1034718
> 
> ...


no luck... rear still has greater lever travel...


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## Cleared2land (Aug 31, 2012)

^^^ Is your Free Stroke Screw all the way in?


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## spyghost (Oct 30, 2012)

Cleared2land said:


> ^^^ Is your Free Stroke Screw all the way in?


yes screwed in all the way both levers


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## Cleared2land (Aug 31, 2012)

You might just need a good bleed. Rear brakes can sometimes be a little more difficult. I have had to remove rear caliper and all tie-wraps to hang the caliper and brake line vertically to free trapped air on a rare occasion.


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## spyghost (Oct 30, 2012)

Cleared2land said:


> You might just need a good bleed. Rear brakes can sometimes be a little more difficult. I have had to remove rear caliper and all tie-wraps to hang the caliper and brake line vertically to free trapped air on a rare occasion.


yep am tempted to do it...

i'll get back as soon as i've done it...

stay tuned...

... while i hope for the best


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## eicca (May 9, 2014)

Also Google "Shimano mini bleed," may help finish off the whole procedure real nice.


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## spyghost (Oct 30, 2012)

eicca said:


> Also Google "Shimano mini bleed," may help finish off the whole procedure real nice.


nope it didn't help. i always do mini bleed (5 min bleed).

haven't dismantled yet though. need to grab additional fluid from the store today... am living in a different timezone


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## spyghost (Oct 30, 2012)

not really sure if what has been done here will help (first post), but will give it a try...

Fix excess brake lever travel

another puzzle to me is that, since my rear can travel 5mm more compared to the front, could it be that my rear has servo wave working correctly and my front is not?

can the servo wave functionality really be by-passed i a sense? how will one know if its working or broken?

can an unequal piston movement contribute to 'excessive' but still firm lever travel?


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## Rmplstlskn (Sep 18, 2015)

Not sure if it will help, but I posted in another thread about M8000 brakes a hack I did that has helped my brake lever travel...

With yellow Shimano bleed block, lever travel is perfect! Small take up and then solid...

Put almost new pads back on and install wheel with new IceTech rotor and the brake levers have a lot more take up before it locks down.

So I am running with the ~assumption~ that Shimano designs the bleed blocks with "most common denominator" in mind, which means on the LOOSE side so all the variable bike systems fit and they don't have a lot of tech support issues...

To fix this, I sanded about 1mm of thickness off the bleed block, making it thinner. I then re-bled the brakes and the lever travel is a lot better. It is now satisfactory for my needs. If I was hardcore XC or DH I would even take more material off the bleed block.

This is essentially what the "overfilling" hack does, just EASIER in my opinion.

Let us know if you try and it helps...

Rmpl


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## spyghost (Oct 30, 2012)

Rmplstlskn said:


> Not sure if it will help, but I posted in another thread about M8000 brakes a hack I did that has helped my brake lever travel...
> 
> With yellow Shimano bleed block, lever travel is perfect! Small take up and then solid...
> 
> ...


i used the same bleed block for both front and rear and the same method for bleeding... its just the rear that acted differently though... i'll try to look into how the pistons move. 'assuming' nothing is broken, it's the only variable left...

its quite difficult to 'nerd' out the numbers blindly which contributes to the additional 5mm movement of the lever in relation to piston movement...


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## eicca (May 9, 2014)

Fully reset all the pistons and see if that helps.


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## spyghost (Oct 30, 2012)

ok, here's what i did... i'm fairly confident that i've bled properly what i did notice is that the rear pads have noticeable movement when the levers are pressed compared to the front pads.

so, i took off the rear wheel, pressed the lever 3 times to bring the pads closer. i put back the rear wheel and behold, the lever travel became shorter - down to 10mm. i did the same for the front and just the same, the lever travel went down to 10mm as well!

i'm pretty sure that the wheels still spin freely, still as if nothing binds. what i did was just bring the pads closer to the rotor and let the spring between the pads handle the separation.

i'll take it out for a spin with some heavy braking and see what happens to the travel afterwards.


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## Cleared2land (Aug 31, 2012)

The only thing to add, if you didn't already, is to center your caliper on the disk.


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## spyghost (Oct 30, 2012)

Cleared2land said:


> The only thing to add, if you didn't already, is to center your caliper on the disk.


yep, centering is always an SOP for me...

it seems i got a somewhat sticky left piston in the rear as it moves slowly compared to the right piston. both pistons seem pretty clean to me and no leaks. i'll just see how it goes. perhaps some sort of bedding in from the seals... i don't know... i've just had this setup for a month or so with minimal mileage still.

i'll keep observing though...


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## Rmplstlskn (Sep 18, 2015)

spyghost said:


> so, i took off the rear wheel, pressed the lever 3 times to bring the pads closer. i put back the rear wheel and behold, the lever travel became shorter - down to 10mm.


Essentially what my thinner bleed block hack above does...

Rmpl


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## spyghost (Oct 30, 2012)

Looking at this writeup: Tech Spotlight - Brake Piston Balancing - Pinkbike



> Long lever throw. This can be from one of the pistons not moving as intended, with the extra throw required to drive the operating piston across the gap left by an ineffective piston.


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## NordieBoy (Sep 26, 2004)

spyghost said:


> Looking at this writeup: Tech Spotlight - Brake Piston Balancing - Pinkbike


But the throw to move 2 pistons 2mm each is the same as to move 1 piston 4mm.


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## spyghost (Oct 30, 2012)

NordieBoy said:


> But the throw to move 2 pistons 2mm each is the same as to move 1 piston 4mm.


ideally both should have equal throw.

in my case, the outer piston throw is lesser than the inner piston throw.


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## jonshonda (Apr 21, 2011)

Deore brakes still going strong after the Iso/burn/sand procedure I did to them.


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## BuickGN (Aug 25, 2008)

NordieBoy said:


> But the throw to move 2 pistons 2mm each is the same as to move 1 piston 4mm.


Exactly. That article is wrong. 4 piston brakes will always move one set of pistons faster than the other set. The leading edge pistons are smaller than the trailing edge pistons to give more even brake pad wear. This means the leading edge pistons are weaker but move quicker and the trailing edge pistons are more powerful but move slower. When you apply the brakes the smaller pistons make contact first and once they stop moving due to rotor contact, the larger pistons move quicker and engage the rotor. If you do what that article says you "reset" the pads where they're parallel to the rotor or "even" you're making the pad contact the rotor unevenly. It's really not a big deal if one piston of a 2 piston caliper or 2 pistons of a 4 pot caliper hit the rotor first but the article actually causes the problem it's trying to fix. On a 4 pot caliper, it's ok if the pad sit with the trailing edge a little closer to the rotor at rest.

Back to what you said, it doesn't matter if one piston moves twice as far as the other or both pistons move the same distance, lever throw is unaffected by an "imbalanced" system. In an 'imbalanced" 2 pot setup the closer piston will hit the rotor first, then the other piston moves twice as fast until it contacts the rotor. Braking does not begin until both pistons contact the rotor (via the pads to the smartasses out there).

Contrary to what some have said, if one piston is frozen, will not move at all, lever throw will be shortened, cut in half, and power will be cut in half.


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## TrondAM (May 28, 2015)

I am experiencing similar problems on my three month old Zee brakes. Front works fine, but rear lacks braking effect and is very noisy upon contact with rotor. Only thing that works is to go down a fast steep track while braking. Afterwards the brake works perfect for the rest of the day. The next morning the power is gone and noise is back. The bike is stored in a humid cellar.

After reading this thread yesterday I took the bike for a ride and put the pads in a plastic bag in the apartment overnight. Going to see if it worked later today.


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## ColinL (Feb 9, 2012)

I solved this long ago on my wife's bike which has M785 XT calipers and icetech rotors.

1) get 2 sets of pads. stock/current set is one, buy a second set. buy a propane torch if you don't already own one. ~$50 at a hardware store, walmart, etc.

2) when squealing occurs, remove pads and clean rotors with rubbing alcohol.

3) put the squealing pads on something that can handle some heat. driveway, sidewalk, big rock.  turn on the torch and get a nice even blue flame. burnish the pads for 10-15 seconds each. let them cool at least 20 minutes to be safe.

4) install good pads. these can be new/unused or pads that have been torched.

5) adjust calipers for optimal pad/rotor clearance if necessary. (shouldn't be if you have 2 sets of identical pads with similar wear.) go ride.

6) after bike sits a while and starts squealing, go back to step 2.


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## c8stom (May 19, 2015)

TrondAM said:


> After reading this thread yesterday I took the bike for a ride and put the pads in a plastic bag in the apartment overnight. Going to see if it worked later today.


Any news ?


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## eicca (May 9, 2014)

I didn't necessarily torch or bake my pads, but my rear brake was fading after sitting for a few days until I took it down a gnarly rotor-burner DH run in the local canyon. No fading since. Another piece of evidence that suggests that moisture is causing oxidation and heating it enough to burn it out solves the problem.


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## kryten (Mar 8, 2012)

I sanded my XT finned resin pads several times, baked them in the oven, cleaner rotors and beaded properly multiple times with no luck.

Finally decided to get new cheap pads to see if it helps before I scrap my XT 785 brakes. Decided on Nukeproof semi metalic non fined pads and upgraded my resin only RT56 rotors (rear was slightly bent anyway) with RT66. 

Brakes work like they should, no squeal and lots of power. Pads are also half price or less. Going on 2 months now without an issue. Not buying Shimano resin pads in the future for sure. Maybe metal ones, ...just maybe, but most likely for the price I will just stick with Nukeproof ones.


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## NordieBoy (Sep 26, 2004)

Love my Shimano finned resin pads.


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## ColinL (Feb 9, 2012)

kryten said:


> I sanded my XT finned resin pads several times, baked them in the oven, cleaner rotors and beaded properly multiple times with no luck.
> 
> Finally decided to get new cheap pads to see if it helps before I scrap my XT 785 brakes. Decided on Nukeproof semi metalic non fined pads and upgraded my resin only RT56 rotors (rear was slightly bent anyway) with RT66.
> 
> Brakes work like they should, no squeal and lots of power. Pads are also half price or less. Going on 2 months now without an issue. Not buying Shimano resin pads in the future for sure. Maybe metal ones, ...just maybe, but most likely for the price I will just stick with Nukeproof ones.


If you search (which you don't actually need to - just take my word for it), earlier in this thread I thought it was Shimano pads. I was happy as could be with some Galfer pads. And then winter hit. Lo and behold, when my wife brought her bike back out in March, the brakes howled like banshees.

No visible leaks can be seen, but it's evident to me that the issue is micro leakage of the piston seals, leading to slow and gradual pad contamination.

Baking is probably not enough, even the broiler on the top rack is pitiful compared to 20 seconds from a MAP / propane torch.

The only reason I suggested 2 pads is that you can prep a set and swap them fast when squeaking returns. If you only have one set, you have to remove them, burnish them, wait for them to cool, then reinstall. You can do that - no doubt.


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## ColinL (Feb 9, 2012)

Wow. I'm way off on pricing, though. I've owned a torch for >20 years and I see that the trigger alone is $30-50+, and a MAP or propane cylinder is $10-12 (which lasts me years). I'll edit that other post.


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## kryten (Mar 8, 2012)

That sucks if it ends up being the case for me too. I suspected a small caliper leak although I could never see it when I inspected my brakes so my last resort was to try new pads and new rotors as they were needed regardless. If it comes back and it is a caliper leak issue after all, these brakes will be thrashed. I don't have time for these games.


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## c8stom (May 19, 2015)

The leak I had was in the banjo area. It was so tiny it took 4 weeks for oil to hit the pads after a thorough cleaning and was impossible to see. I discovered the leak by running my fingers around the calipers an looking for oily residue. After a hose replacement, the problem went away. The brake has not squealed at all 18 months and I live in a tropical climate ( over 30 deg C, > 90% humid )


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## eicca (May 9, 2014)

If sanding a layer off the pads fixes the issue, it's not oil, it's the "phantom fading". If sanding, baking, etc doesn't fix the issue, it's oil.


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## NordieBoy (Sep 26, 2004)

Torching it will fix it temporarily even if it is oil.


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## ColinL (Feb 9, 2012)

NordieBoy said:


> Torching it will fix it temporarily even if it is oil.


Damn right it will! :thumbsup:


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## eicca (May 9, 2014)

NordieBoy said:


> Torching it will fix it temporarily even if it is oil.


Only fixed it for about 20 seconds yesterday.


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## ColinL (Feb 9, 2012)

eicca said:


> Only fixed it for about 20 seconds yesterday.


did you follow the exact steps I mentioned in this post?

I would initially suspect you didn't clean the rotors. A lot of people have replaced them, which is not necessary. Cleaning is quite adequate because rotors are not permeable like brake pads, and so any contaminants on them can easily be wiped off with the correct cleaning product.

My next guess is that you didn't actually burn them for 10-20 seconds (each) with a torch.

Finally, if you've done all of that, it would indicate you've got a significant leak at the caliper. It should be visible. Several generations ago, XT brakes were infamous for caliper leaks. It was visible.

By the time M785 rolled around, it was visibly fixed. But it seems that it's still leaking a little bit... just enough to contaminate the pads if you have significant gaps in riding. Once you start to get the squeak, it's only going to get worse - more contaminated, until you follow the process I wrote.


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## eicca (May 9, 2014)

Oh trust me. I cooked both pads and the rotor generously using alcohol and some highly flammable aerosol degreaser. The fact that it didn't work was offset by how fun it was.


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## ColinL (Feb 9, 2012)

eicca said:


> Oh trust me. I cooked both pads and the rotor generously using alcohol and some highly flammable aerosol degreaser. The fact that it didn't work was offset by how fun it was.


aerosol is not a MAPP or propane torch. you did not burn it sufficiently to remove all the brake fluid.

instead, just buy a new set of brake pads. before you install them, WIPING the rotors with rubbing alcohol is sufficient. before the new set becomes contaminated enough to squeak, buy a real torch.


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## gastonbx (Oct 15, 2009)

ColinL said:


> aerosol is not a MAPP or propane torch. you did not burn it sufficiently to remove all the brake fluid.
> 
> instead, just buy a new set of brake pads. before you install them, WIPING the rotors with rubbing alcohol is sufficient. before the new set becomes contaminated enough to squeak, buy a real torch.


I am experiencing the exact same issue, on two bikes, both rear brakes, with old and just installed brake pads. As somebody already said, torching the pads and cleaning the rotor will only work for half -or even less- of a ride.

The bikes are all in the same place, a room in my appartment. The other bikes, all with "old" Elixir 5, CR, or Code, do not have any issues.

This issue is really annoing me, I can't understand which is the factor that kills my rear brakes every time I do not use the bikes.

Thanks all for the provided solutions.


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## NordieBoy (Sep 26, 2004)

Torching works for several weeks for me.


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## batmnx (Jul 18, 2016)

I would like to comment on this as i broke my almost new 2016 xtr carbon lever i think its not that tough considering its price, i hope shimano will do something about this thin carbon lever which has a tendency to break at the far third portion as i also read an article review mentioning about breaking it also thanks


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## ColinL (Feb 9, 2012)

batmnx said:


> I would like to comment on this as i broke my almost new 2016 xtr carbon lever i think its not that tough considering its price, i hope shimano will do something about this thin carbon lever which has a tendency to break at the far third portion as i also read an article review mentioning about breaking it also thanks


welcome to MTBR.

this thread you've replied to has absolutely nothing to do with XTR lever durability. you might search again, or post a new thread about it if you don't find one.


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## MSU Alum (Aug 8, 2009)

I have 3 bikes with XT brakes. None of them had problems until I got out on my new bike. Turns out that the rear brake mount was just slightly misaligned. After having them faced, the noise was still there, but I attributed it to the pads and disc being worn in to the misaligned mount. After replacing the pads and disc, the problem has gone away and has not returned.


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## Mikeerac (Jun 26, 2009)

Just to add my tuppence worth... I use my deore M615 equipped bike for both a commute to work and XC, went on holiday for two weeks and suffered the same problem on the back brake. Squealing and no power. Lever travel was good but I burped the caliper anyway by screwing in the bleed pot into the lever, adding an inch of fluid and tapping the caliper and squeezing the lever, one bubble appeared but made no difference. I then took out the pads and checked the bleed nipple and hose connector, they were both dry but dusty. I then cleaned the rotor with brake cleaner, sprayed the very dusty caliper and pistons and cleaned those. Then using the advice here, used my cooks blowtorch to heat the pads for 15-20 secs, light smoke was given off. After cooling I put them back in and did five emergency stops to bed them in again. Stop got better and better, by the 4th stop I could lock the rear with no squealing. Rode in to work this morning and no squealing and full power. I had to emergency stop when someone ran in front of the bike so all good now. I suspect it's a problem with the pads glazing due to lack of use. I also think that pads glazing in two weeks is a bit of a design fault by Shimano.


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## NordieBoy (Sep 26, 2004)

The pads can only glaze with use. They can absorb moisture when sitting though.


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## ColinL (Feb 9, 2012)

Mikeerac said:


> I suspect it's a problem with the pads glazing due to lack of use. I also think that pads glazing in two weeks is a bit of a design fault by Shimano.


Nope. It's absorbing brake fluid which is coming from the piston seals in minute amounts.Those minute amounts add up to enough to impair braking performance if the bike sits a while.


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## NordieBoy (Sep 26, 2004)

ColinL said:


> Nope. It's absorbing brake fluid which is coming from the piston seals in minute amounts.Those minute amounts add up to enough to impair braking performance if the bike sits a while.


This doesn't feel right to me.
The fluid would have to migrate post the seals, onto the pistons, onto the back of the pad, down to the bottom of the backing material, up onto the pad material.
All with no pressure in the system, no wind, no external influence.
If it happened whilst riding, I could understand it.


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## brentos (May 19, 2006)

Another point to investigate is the crimp between the banjo at the caliper and the hose. I had one leak there, causing this issue.


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## Cleared2land (Aug 31, 2012)

ColinL said:


> Nope. It's absorbing brake fluid which is coming from the piston seals in minute amounts.Those minute amounts add up to enough to impair braking performance if the bike sits a while.


Sorry, I'm not buying your take on this at all. I'm not sure what this well documented Shimano brake fade problem is, but I lean to the 'oxidation' sort of theory.

But I have no idea what the real culprit is.


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## eicca (May 9, 2014)

The oxidation theory holds because sanding the pads brings performance right back. Until it they sit again, and then glaze over. And then you have to sand them again. The Shimano guy I talked to said if it were oil contamination, sanding the pads would have no affect.


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## ColinL (Feb 9, 2012)

hi


eicca said:


> The oxidation theory holds because sanding the pads brings performance right back. Until it they sit again, and then glaze over. And then you have to sand them again. The Shimano guy I talked to said if it were oil contamination, sanding the pads would have no affect.


the problem is that this theory is very easily disproven. two sets of pads, one out of the caliper in open air. it would oxidize, right? and all pads are affected, metallic or organic, and they all come back with some heat.

maybe I'm wrong about the piston seals. maybe it's the banjo bolt. I don't really care, because it is definitely brake fluid contamination.


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## 11053 (Sep 19, 2009)

ColinL said:


> hi
> 
> the problem is that this theory is very easily disproven. two sets of pads, one out of the caliper in open air. it would oxidize, right? and all pads are affected, metallic or organic, and they all come back with some heat.
> 
> maybe I'm wrong about the piston seals. maybe it's the banjo bolt. I don't really care, because it is definitely brake fluid contamination.


Nope, brake fluid may not be the culprit. It certainly hasn't been for me.

The loss of power/grab for used Shimano brake pads after sitting inactive has been one of the great mysteries of life.

Yes, all pad types can be affected.

I currently have three bikes with Shimano brakes.

On all of them, I can ride the brake pads down to almost nothing with absolutely no loss of power/grab for the life of the pad as long as the brakes are used frequently-meaning they never sit for more than a few weeks.

On all 3 bikes, if the pads are used and then left to sit for extended time- all brakes/pads exhibit the loss of power/no grab funk.

After last bike park season I removed a set of Saint pads from my park bike and let them sit off the bike for the winter/spring. Pads were pretty fresh as they had been replaced near the end of the season. Performance was 100% till the season ended.

After winter, I removed a set of XT pads from my fatbike and let them sit for the summer. Plenty of life in the pads even though they saw significant trail time in winter. Perfect performance prior to removal.

On bike # 3 I left the XT pads on for the entire winter + spring but didn't remove the pads from the bike. Those pads only saw a few bike park days and were pretty fresh. Bike sat unused for months.

I have long experienced the Shimano no grab after sitting funk.
This winter+ summer I put new pads -Saint + XT that were removed from packaging next to the used pads that were taken off the bike. All pads sat for the same length of time.

Put the used Saints back on after sitting=no power. They were perfect till removed from the bike and left to sit.
Put the used XTs back on the fattie=no power.
Put on the new/exposed pads that were left to sit next to the used pads=full power and no problem.
Bike that was left to sit with used pads and no activity for months=no power. On this bike I then replaced pads but did not ride the bike for months. New pads left to sit on the bike= full power + performance after sitting unused on the bike.

Brake fluid theory doesn't hold for me.


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## ColinL (Feb 9, 2012)

Honestly I'm fine never knowing the root causes. What matters most is the fix: removing the pads and burnishing them with a torch. Clean the rotors with rubbing alcohol or something else that you can be sure will not remain on the rotor afterwards.

Re-install pads and go ride.. :thumbsup:


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## Cleared2land (Aug 31, 2012)

ColinL said:


> maybe I'm wrong about the piston seals. maybe it's the banjo bolt.* I don't really care, because it is definitely brake fluid contamination*.


I have to assume you're making reference to YOUR situation. Because I definitely have no fluid contamination.


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## ColinL (Feb 9, 2012)

Cleared2land said:


> I have to assume you're making reference to YOUR situation. Because I definitely have no fluid contamination.


Wonderful. What's your theory? Perhaps you may have noticed, earlier in this thread, others have posted their experiences with many types of brake pads, not just Shimano. They all do this, eventually, given enough time. So, explain that?


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## Cleared2land (Aug 31, 2012)

ColinL said:


> Wonderful. What's your theory? Perhaps you may have noticed, earlier in this thread, others have posted their experiences with many types of brake pads, not just Shimano. They all do this, eventually, given enough time. So, explain that?


See post # 241



ColinL said:


> They all do this, eventually, given enough time. So, explain that?


Define eventually? I two other bikes with XT's and they have over 14,800 accumulate miles with no leaks or brake fluid related issues or problems.


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## ColinL (Feb 9, 2012)

Cleared2land said:


> Define eventually? I two other bikes with XT's and they have over 14,800 accumulate miles with no leaks or brake fluid related issues or problems.


Eventually means that it takes a certain amount of time of NOT riding the bikes. Which, in some climates, is easily done in mid-winter. Others have multiple bikes and achieve it that way. Still others aren't riding very often.

So, test your theory. Get a set of pads- based on the thread, it truly doesn't matter what brand or model, but you can specify it anyway. Leave them near wherever you store your bike. Leave them there a few weeks and install, then try them.


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## NordieBoy (Sep 26, 2004)

ColinL said:


> Wonderful. What's your theory? Perhaps you may have noticed, earlier in this thread, others have posted their experiences with many types of brake pads, not just Shimano. They all do this, eventually, given enough time. So, explain that?


I have to torch my BB7 pads occasionally after non-use to stop the squeal. No fluid contamination there...


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## Jayem (Jul 16, 2005)

I've experienced this a few times, it seems to only happen with my XTR brakes, although I have to wonder now about some things I've experienced in the past with Hope and Avid.

The most recent time, I had let my hardtail sit for 2-3 weeks, put the fat-wheels and tires back on, which happen to include Ai2 disc rotors, and I had no freaking braking and tons of howling on the way to work. They were working just fine on the AirRotors on the skinny wheelset. So the next morning I put the pads in the oven at 400 for 20 minutes, cleaned the rotors well with alcohol, and bamn, they worked great, in fact pretty dang impressive how little rotor surface I have (when it gets to be winter they work fantastic, since we don't have to worry too much about overheating in Alaska).

I can't remember this happening with my XTs, but I think I did throw them in the oven and clean the rotors as described before some of the riding this year. 

I'm not convinced it's just the pads, it seems to be possibly a combination of the pads and the rotor, although the rotor is of course impregnated with some of the pad material.


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## bitewerks (May 14, 2009)

So, if the pads can soak up humidity while sitting idle, what can be done to minimize it when you know the bike's going to sit for a week or two (or longer) while it's raining & very humid out? I'm in Texas so that's my spring and summer.

I recently had the described issue with my front brake (squealing, loss of power after sitting for 5-6 days). I may have contaminated the pads when I sprayed the front tire off & the weeping Stan's got onto the brake (there was spatter around the area with the bleed nut). I threw in old pads & everything was okay for a few rides but now I've got the squealing so I'm going to replace the rotor and pads in a couple of days. I have seen no signs of leaks. The rotor is 3+ years old.


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## Mikeerac (Jun 26, 2009)

Bitewerks, try the fix mentioned earlier before buying new pads and rotors. Take the pads out and clean the rotors with brake cleaner or alcohol and blowtorch the pads for 15secs. After five emergency stops mine were back to normal and have stayed that way. I think the only thing to try would be to remove the pads and keep them in the house if you are not riding for a couple of weeks.


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## bitewerks (May 14, 2009)

I've already purchased pads & a rotor- found good deals on eBay.

I'll do the cleaning later then try it on the rear (running 160mm on the rear & have wanted to up to 180mm). Also, I don't have a blowtorch. I did take the possibly contaminated pads & held them over a stove flame for a handful of seconds but haven't tried them yet.



Mikeerac said:


> Bitewerks, try the fix mentioned earlier before buying new pads and rotors. Take the pads out and clean the rotors with brake cleaner or alcohol and blowtorch the pads for 15secs. After five emergency stops mine were back to normal and have stayed that way. I think the only thing to try would be to remove the pads and keep them in the house if you are not riding for a couple of weeks.


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## eicca (May 9, 2014)

Bake them for 10 minutes at 400, that'll do the same thing.

Then stick a toothpick in the middle and see if they're done.


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## Mikeerac (Jun 26, 2009)

10 mins? I prefer my brake pads medium rare!


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## BuickGN (Aug 25, 2008)

eicca said:


> Bake them for 10 minutes at 400, that'll do the same thing.
> 
> Then stick a toothpick in the middle and see if they're done.


Baking at 400F will not do the same thing as a torch. Shimano mineral oil doesn't even boil until >500F so it's certainly not going to burn off at 400F in 10 minutes. If the pads have any sort of fluid contamination, an open flame is needed to get all of the fluid contamination out of them.

It's possible you might evaporate off a little surface contamination, giving a temporary improvement in braking, but the problem will be back shortly since the pads are porous and you will never get all of the oil out from within, in a reasonable amount of time through baking.


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## ColinL (Feb 9, 2012)

BuickGN said:


> Baking at 400F will not do the same thing as a torch. Shimano mineral oil doesn't even boil until >500F so it's certainly not going to burn off at 400F in 10 minutes. If the pads have any sort of fluid contamination, an open flame is needed to get all of the fluid contamination out of them.
> 
> It's possible you might evaporate off a little surface contamination, giving a temporary improvement in braking, but the problem will be back shortly since the pads are porous and you will never get all of the oil out from within, in a reasonable amount of time through baking.


I pointed that out to eicca back in June, well documented on page 5 of this thread.

Unsubscribing now... Good luck to y'all.


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## eicca (May 9, 2014)

Again, it's not oil that causes it to glaze when not in use. My collection of experiences at my shop plus the input from the Shimano tech I talked to all say it's not oil. If it were oil, sanding the pads would not bring the power back. A downhill run would not bring the power back.

If you have an oil leak that's one thing. We are trying to figure out a solution to what appears to be moisture. Baking for 10 minutes at 400 will do it. So will a heavy-braking downhill run, as I have confirmed almost every time my brakes do this. They fade after not being used. Then when I drag them at high speed, they're fine for the entire rest of the ride.


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## rfxc (Oct 18, 2004)

eicca said:


> Again, it's not oil that causes it to glaze when not in use. My collection of experiences at my shop plus the input from the Shimano tech I talked to all say it's not oil. If it were oil, sanding the pads would not bring the power back. A downhill run would not bring the power back.
> 
> If you have an oil leak that's one thing. We are trying to figure out a solution to what appears to be moisture. Baking for 10 minutes at 400 will do it. So will a heavy-braking downhill run, as I have confirmed almost every time my brakes do this. They fade after not being used. Then when I drag them at high speed, they're fine for the entire rest of the ride.


I have swapped pads between my TRP spyres (mechanical) and xt 785 and xtr 980 brakes. the contamination/squeal only occurs in the 785/980 brakes. I'm reasonably confident that over time, sitting, oil seeps past the piston seals and contaminates pads. Hitting them with a torch has become a habit for me after a bike sits for awhile.

I have another bike with xtr 9020 brakes, which twice this year has sat for over a month-- no such issues.


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## Cleared2land (Aug 31, 2012)

If the seals are leaking, it will be an easy visual confirmation.


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## kryten (Mar 8, 2012)

kryten said:


> I sanded my XT finned resin pads several times, baked them in the oven, cleaner rotors and beaded properly multiple times with no luck.
> 
> Finally decided to get new cheap pads to see if it helps before I scrap my XT 785 brakes. Decided on Nukeproof semi metalic non fined pads and upgraded my resin only RT56 rotors (rear was slightly bent anyway) with RT66.
> 
> Brakes work like they should, no squeal and lots of power. Pads are also half price or less. Going on 2 months now without an issue. Not buying Shimano resin pads in the future for sure. Maybe metal ones, ...just maybe, but most likely for the price I will just stick with Nukeproof ones.





ColinL said:


> If you search (which you don't actually need to - just take my word for it), earlier in this thread I thought it was Shimano pads. I was happy as could be with some Galfer pads. And then winter hit. Lo and behold, when my wife brought her bike back out in March, the brakes howled like banshees.
> 
> No visible leaks can be seen, but it's evident to me that the issue is micro leakage of the piston seals, leading to slow and gradual pad contamination.
> 
> ...





kryten said:


> That sucks if it ends up being the case for me too. I suspected a small caliper leak although I could never see it when I inspected my brakes so my last resort was to try new pads and new rotors as they were needed regardless. If it comes back and it is a caliper leak issue after all, these brakes will be thrashed. I don't have time for these games.


Just an update since June. Did only a few rides throughout the summer (busy with work), but used it quite a bit during September. So far my brakes work the same as the day I put in the Nukeproof pads almost 6 months ago, so I'm happy.


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## mik_git (Feb 4, 2004)

Happy..happy, thats not the word I guess, to find this thread. Same problem as most here, XT 785 brakes, working perfectly, hung that bike up in the spare room back in April (omg it was actually that long), grabbed the bike just for the 2km ride into town to pick up the car, no rear brake apart from a heap of squeeling. It has been a wet, wet winter here (Australia) like I don't even remember. So time to try the long DH's to see what happens...then the baking...

And also to try the other bike, same brakes but used a bit more (not much though, most of the trails have been closed due to rain for months)...

V-brake equipped bike is fine though


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## mik_git (Feb 4, 2004)

well took bike out today to small hill near me, 1st run, mega squeal and no power, by the bottom of the second run power came back and wheel locked up, sill squealing, 3rd run power fine more than the front I think, and still squealing but not real bad... so thats good, back to ridable now, just need to take to for a good ride.

Now to bleed the other bike


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## Turts (Aug 30, 2015)

Well damn it. 
Add me to the list. Installed new Zee front and rear with Ice Tech roots. 
Wonderful brakes all summer. 
Bike sat for awhile and yup, both ends howling and barely any friction between the pads and rotors. 
Pissed me off, put the bike back into the garage and walked away. 


Sent from my iPhone using Tapatalk


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## jonshonda (Apr 21, 2011)

My fat bike hung in my basement all summer and I pulled it down the other day to get it ready for winter. Imagine my surprise when the deore brakes have next to zero power and the noise.....ohh the glorious noises. 

I also found a nice stream of fluid coming from my rear caliper. Time to see if the lbs will trade me for some XT's. People talk up shimano brakes, but I wish I had the cash to run hopes on all my bikes.


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## craftworks (Aug 24, 2004)

*Walk away*

Every shimano brake I have owned has this inherent problem.

Front and rear brakes have next to zero friction although a perfect lever feel. Yes the noise is low end characteristic of a low end brake system.

Rear brake is the first to come back on line after a couple of hours of riding , due to the heavier usage. Front is just a joke.

Band aid approach swap pads front to rear eventually brings brakes back to life.

All gone to **** again when bike is not riden for a month. Same goes with my other bike with shimano 
Brakes

XTR, XTR trail , Saints , Zee all currently worthless until the pads get cooked

Sick of it


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## bridgestone14 (Mar 22, 2005)

hmm haven't read through the whole thread but just had this happen to a set of older xt brakes. The large torx bolt that holds the caliber together was a touch loose. Of course I had torn the whole brake apart before I figured it out. Might not be your problem but something to check and easy to check before you get into harder fixes.


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## ketvok (Oct 4, 2015)

2 week old Zee M640 brake set, came with resin pads. Worked fine for two weeks. Used with Shimano RT-61 rotors from a previous bike. Ridden in around 0 C temperature. Stored in a cold basement. Ridden every evening. Then one evening I went for a ride as usual, and when I needed to brake with my rear brake there was almost no braking power, I was barely able to stop and not crash. Front brake seemed fine at the moment. Two days later (yesterday), I went out to test the brakes again. This time both front and rear were very weak, as if they were brand new, and they had tendency to squeal.

In conclusion: sudden overnight power loss from both Zee brakes, only two weeks old. Fitted on my bike with no bleeding or hose shortening. Lever firmness excellent.

This is like a bad dream...


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## c3024446 (Apr 16, 2010)

I've tried to solve this problem just then - put some g01a (resin with aluminium backing) under a propane torch - the pad material came away from the backing plate on 4 out of the 6 pads I torched to red hot. The 4 pads I torched with the steel backing plate seem OK. Bit concerned now.


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## Guest (Jan 19, 2017)

c3024446 said:


> I've tried to solve this problem just then - put some g01a (resin with aluminium backing) under a propane torch - the pad material came away from the backing plate on 4 out of the 6 pads I torched to red hot. The 4 pads I torched with the steel backing plate seem OK. Bit concerned now.


 Red hot? The previous discussion was 15 seconds under the torch.


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## Cleared2land (Aug 31, 2012)

c3024446 said:


> the pad material came away from the backing plate on 4 out of the 6 pads I torched to red hot.


RED HOT? I would only do this until the pads became hot enough to burn off any residual material or until a light smoking stopped.

My suggestion would be to toss those 'Hot Pads' and get new ones.


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## c3024446 (Apr 16, 2010)

It was a very hot torch and I may have burned them for 30 seconds each. I've binned them. The pads weren't working anyway. 

Think I'll give some of the Discobrake Kevlars a go. They work great with my Avid XX's.


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## jimPacNW (Feb 26, 2013)

Aftermarket sintered metallic pads do it too, but no noise, just no bite or stopping power. My race bike sat in the bsmt since late November, rode it today, not much stopping power! The rear is back to 90% and the front to about 60% after 80 min of riding.


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## allu (Aug 23, 2016)

My bike came with SLX brakes that have been running flawlessly until today's ride. It was just above freezing, a beautiful day but of course when everything else was working perfectly the brakes start acting up. I usually store the bike outside in the temperature it's ridden at, but I have had the bike indoors for nearly a week now due to new parts arriving every couple of days. I wonder if this made the difference? As soon as I got out the brakes had zero grip and they weren't biting at all. Instead they just had this cheapo brake howl on them that continued all the way to the end of the two hour ride. It did get noticeably quieter and the power came back after a few miles, but the howl was still there. I'm nearly 100% sure the pads aren't contaminated unless the chain oil made some awesome ninja jump to the rotor so it must be something else. Possible the same thing happening in this thread, moisture being absorbed into the pads? I put the bike back outside and we'll see this weekend whether it's temperature related or not.


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## jimPacNW (Feb 26, 2013)

I pulled my pads, rubbed them on some flat sandpaper and took the nasty looking stuff off, rode today; they re-bedded in quickly and are 'on' again.


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## allu (Aug 23, 2016)

Brake cleaner on rotors, for brake pads 10-15 minutes in 200C/400F oven and gentle clean up with a tissue helped immensely and the brakes work like new now. Wasn't oil for sure, we'll see how quickly the issue comes back. Oh well, at least there's a quick fix for it now.


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## HENGST101 (Mar 6, 2013)

Take the Shimano brake pads and throw them away. By yourself Swiss stop brake pads and it should fix the problem. Had the loss of power problem on my Shimano Saint brakes after sitting idle. I've put swissstop metallic pads on my saint brakes and they are the bomb. No loss of power after sitting idle.


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## Guest (Mar 22, 2017)

I think you're solving the wrong problem. Rather than figuring out how to fix the brakes, you should be thinking of ways to ride every week.


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## HENGST101 (Mar 6, 2013)

Sure thing there Forster


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## NordieBoy (Sep 26, 2004)

Torched some front and rear pads the other day.
Front were running fine, rear were noisy and way down on power.
Front torched silently. Rear were popping away as things burned off and moisture was forced out.
Much better now.


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## -Todd- (Jun 13, 2011)

Brought my trail bike up from the basement after sitting for 5? months, the 985 XTR trail brakes worked flawlessly. No shortage of power, no issue with modulation.


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## noot (Jul 7, 2008)

My new saints have done this from day 1 (which was about 2mo ago). Even overnight, first few stops are scary. Even "warmed up", they aren't nearly as good as I expected. 

Will be torching today - and will update the thread.


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## Cleared2land (Aug 31, 2012)

I have now done the propane torch a few times and was very impressed with the improvement.


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## Aglo (Dec 16, 2014)

noot said:


> My new saints have done this from day 1 (which was about 2mo ago). Even overnight, first few stops are scary. Even "warmed up", they aren't nearly as good as I expected.
> 
> Will be torching today - and will update the thread.


Don't forget to do a proper bed in of the pads. And clean your rotors with alcohol.


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## noot (Jul 7, 2008)

Aglo said:


> Don't forget to do a proper bed in of the pads. And clean your rotors with alcohol.


As promised: ride report. First ride since the pad torching.

I did not touch rotors, nor did I do anything particularly fancy for bedding them in.

They not only worked properly (with none of the "glazing" effect at all), but they actually worked better than they ever had.

Remember, this was on 2mo old pads with maybe 100km on them - both front and rear had this problem. If I had to guess, I'd say they both came somewhat contaminated from the factory.

Long story short - try the torch!


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## eicca (May 9, 2014)

OFFICIAL FIX!

I had the power-loss issue with both resin and metallic pads, and I can confirm that after baking my pads at 400F for about 30 minutes, then sanding them down, they no longer get squeaky after a day or two of not using. I let my bike sit for two weeks after baking and sanding and the pads are still perfect. They used to go "bad" overnight.


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## Jayem (Jul 16, 2005)

eicca said:


> OFFICIAL FIX!
> 
> I had the power-loss issue with both resin and metallic pads, and I can confirm that after baking my pads at 400F for about 30 minutes, then sanding them down, they no longer get squeaky after a day or two of not using. I let my bike sit for two weeks after baking and sanding and the pads are still perfect. They used to go "bad" overnight.


Yeah, that's what I do if I've let them sit for a while, plus some alcohol for the pads and caliper.


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## Slurry (Dec 23, 2008)

Has anyone ever heard anything from Shimano on this issue (publicly or otherwise?) The best I ever got was a CS agent saying that, "he'd maybe heard of a few isolated incidences". This was four years ago, when I got something like 3 rotors and 4 pairs of brake pads replaced under warranty after they all "glazed/hardend/failed-inexplicably" while sitting idle in my garage for three months in the summer.

I still have Saint M820 brakes and SLX brakes that do this, the 820s more so than the SLX. I've taken to just buying the cheapest, un-hardened rotors shimano makes (~$15-$20 a wheel), because I know they won't even last a season.

I've done Shimano's prescribed leak test(s). I've tried different combinations of rotors and pads. I've tried a bunch of techniques to evenly resurface rotors with abrasives (which honestly can do more harm than good if you do it wrong). I even took a set of rotors to a surface grinder to get them resurfaced. Everything works to some degree, but only temporarily.

It's at the point where I can hop on my bike after a few weeks of non-use and have _literally zero confidence_ that my brakes will work.

Combine this problem with the floating-bite-point issue & cracking ceramic pistons, and I'm getting ready to try another brand altogether.

Shimano got sued in the 90s for a cantilever brake failure (which tbh sounded more like operator error than anything), and yet they had a massive recall campaign and seem to have changed their brake design philosophy to make their primary focus on safety and reliability. I can't believe they're not aware of this issue, and I want them to come out and address it, whether that's through a voluntary recall or through an official repair method.


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## eicca (May 9, 2014)

Baking the pads is as close to an official repair as you’re going to get for now.

I still have the contact for one of the guys at Shimano. I’ll send him my findings.


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## Cleared2land (Aug 31, 2012)

Baking the pads is not really a break-through. This has been a recognized and known possible fix based on number of factors for many years.


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## eicca (May 9, 2014)

Cleared2land said:


> Baking the pads is not really a break-through. This has been a recognized and known possible fix based on number of factors for many years.


But it does support the theory the Shimano guy and I developed that moisture is somehow saturating the pads and causing them to oxidize when not in use.


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## Sparkman999 (Dec 19, 2017)

eicca said:


> But it does support the theory the Shimano guy and I developed that moisture is somehow saturating the pads and causing them to oxidize when not in use.


Does it only happen in humid climates? It's pretty arid where we live and it has not happened to any of our brakes and all our bikes use Shimano brakes with Shimano pads.


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## MSU Alum (Aug 8, 2009)

In the past several years, I've had 5 bikes with M8000 XT brakes and ice-tech rotors. I never take any particular care in preventing "contamination". Also, I don't ride from November to about April. I've used metallic (my current favorite pad because they last) and organic pads. Of those 10 brakes, I've had one that would not stop squeaking and it was a bad piston replaced on warranty. 

First day out on my bikes in April or so, they work just fine. I'm guessing these problems are older generation Shimano brakes, or poorly adjusted ones. The one thing I do regularly is clean out the area in where the pistons move. If that gets gunked up, then one piston will move while the other does not and now you have hydraulic BB7's, which will make plenty of noise. 

Edit: BTW, I'm up in Park City, Utah, so my bikes sit in a fairly damp basement for the whole ski season before I ride them again.


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## NordieBoy (Sep 26, 2004)

eicca said:


> But it does support the theory the Shimano guy and I developed that moisture is somehow saturating the pads and causing them to oxidize when not in use.


Not just Shimano.
I think the pads are slightly porus and moisture gets in and as the pad heats up, released as vapor on the pad surface.
Torch them and sometimes they pop and spark as they get nice and hot.

I seem to have less of a problem with my Shimano's than SRAM.


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## eicca (May 9, 2014)

It's pretty dry here in Utah too, but this problem seems to occur after letting the bikes sit unused for a winter. It's happened on my older Deores as well as some of our shop's brand-new SLX and XTs.


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## jhymel (May 27, 2009)

When I bought my Pivot last year it came with XT brakes and metallic pads. I went through one set (F/R) without ever having the issue of losing of power after sitting the bike up for a few weeks at a time. When I replaced them, I had two new sets that I had gotten on sale a year before I got the bike and they were just in my tool box waiting to be used. I've had to bake those replacement pads a couple of times. I wonder if Shimano changed the pad compound formula on the newer stuff. I'll have to go check and see if I still have the old pads and if they are the same model number.

On my Lynskey 29'er that hardly gets ridden, I have to bake those pads almost every time I ride it since it's usually a few months in between using that bike. Those are definitely older pads that what came on my Pivot.

Is anyone have problems with Shimano pads that were bought within the last year?


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## Slurry (Dec 23, 2008)

jhymel said:


> Is anyone have problems with Shimano pads that were bought within the last year?


Rear organic pads were purchased around new years. No clue when they were manufactured.


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## jhymel (May 27, 2009)

I found this other thread that indicates there was a newer pad released J04C, which was the original pad on my Pivot. All the other pads I've been using were the F03C. Supposedly the J04C uses a different pad compound formula. If that's true that may explain why I didn't have an issue with the ones that came on my bike. Jenson has the J04C on sale so I bought a couple. I'll need to replace my pad soon so I'll see if they make a difference.

Shimano F03C vs J04C pads..?- Mtbr.com


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## RAKC Ind (Jan 27, 2017)

Oddly I've never had this issue except a rear caliper that would have a sticky piston first ride after the winter storage. That was m615 brakes.

My trial bike now is m7000s. Sat for 4 months in a humid or extremely cold garage over the winter, sits for a couple weeks lately sometimes due to rain. Never an issue.

My m445s with cheap Shimano rotors always had issues after sitting for a while. Got better rotors and torched the pads, not a single problem since in 8 months of total crap condition use on my fat bike.

Seems to be more of a rotor issue, oxidation that forms on it. But even then couple good descents and noise gone for rest of the ride.

Sent from my SM-G950U using Tapatalk


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## pktrain (Dec 10, 2007)

Just chiming in to say I have/had this problem with my XTR Race brakes from 2015. After sitting for a few weeks/months, the front brake got super super squeally and weak. After ignorantly tossing the stock pads and replacing with Truckerco organics, the same thing happened. So I found this thread and hit them with the blowtorch until they flamed up a few times, cooked them real good. I let them cool, reinstalled, and whoa, phenomenal braking now. And if/when this happens again, I have a reason to start another fire. Cool.


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## Wish I Were Riding (Jan 30, 2004)

I have XT brakes. Had ACL surgery on my left knee. Now 6 months later and I'm trying to get back into riding and my brakes are terrible. The brakes actually leaked a few times which I thought was very strange. The levers feel okay, but something is clearly wrong.

Just happened to see this thread title. Now I need to go read about the possible fix...


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## Jayem (Jul 16, 2005)

Wish I Were Riding said:


> I have XT brakes. Had ACL surgery on my left knee. Now 6 months later and I'm trying to get back into riding and my brakes are terrible. The brakes actually leaked a few times which I thought was very strange. The levers feel okay, but something is clearly wrong.
> 
> Just happened to see this thread title. Now I need to go read about the possible fix...


Bleed them, learn how to do the shimano quick-bleed, put the pads in the oven at 400 degrees for 20 minutes, clean the pads and the rotor with isopropyl alcohol. This should produce quick results. If not, warranty them and let shimano know they are full of crap for not making seal-kits for their brakes.


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## JonMX5 (Dec 22, 2011)

I'm at my wits end with Shimano. My bike came with SLX brakes and they were great when I rode regularly (basically every weekend).

Now, my riding is less regular. All it takes is two weeks without riding and they squeal like crazy. It doesn't matter if I keep my bike in the house in the garage. I decided to upgrade to Icetech pads and rotors and it's the same damn problem. My calipers shown no signs of leaking and they still do it regardless.

Both the rotors and pads will develop a sheen after sitting for a week or so. It's become a regular occurrence to have to sand my rotors and pads before every ride now which I should not have to do on supposed higher end brakes.

Now that I'm done bitching, can anyone recommend pads and rotors that _don't_ have this constant issue?


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## Aresab (Mar 27, 2007)

I've been using TruckerCo Semi (and for downhill sintered) for years and they do not exhibit the symptom in this thread; which I have also seen myself. If you buy them on eBay they are 26.99 for 4 sets / 2 bikes worth.


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## pktrain (Dec 10, 2007)

Quick update on this...

This problem recurs every 6-8 weeks. I’ve tried Truckerco and Shinano pads. Blow torching only seems to provide a short term solution.

I sold my XTR brakes and put SRAM guide RSCs on my bike and couldn’t be happier.


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## pktrain (Dec 10, 2007)

JonMX5 said:


> Now that I'm done bitching, can anyone recommend pads and rotors that _don't_ have this constant issue?


I switched to SRAM Guide RSC brakes and Centerline rotors and they've been working really well for me.


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## mxxmikexx (Oct 17, 2015)

I going insane with this same issue! i have XT brakes on all my bikes and only ONE has been driving me nuts! the rear brake on my bucksaw i dont see any fluid leaking past the seal on the caliper piston, but i literally have to remove the pads after every ride, clean them, and leave them out till the next ride. and i ride EVERY SINGLE DAY. if i leave the pads in overnight, by the next ride 24 hours later they squeal like a pig. the original sram guides were bunk with the lever sticking issue, so i bought xt for the bike,. i never had issues with xt's until now and its driving my nuts


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## ninjichor (Jul 12, 2018)

What have you been riding your Bucksaw through, @mxxmikexx? The theory that the pads get oxidized sounds like it may have some merit in your case.

Whatever the issue is with set of brakes is, I think the real issue is why you aren't just getting new pads, and possibly a rotor, considering that you're going insane from the degraded performance, despite attempts at cleaning. Venting here is not even a temporary fix. It's maybe $30 for a set of B01S pads and RT66 rotor (might not need the rotor, so less than $10 for the pads), to happily send you off on your way with a more permanent fix. Maybe some extra preventative maintenance steps for your Bucksaw for extra peace of mind?

P.S. I read a number of articles which purposely contaminated a new brake pad and rotor, and tested before and after, and tried to restore power. They tried many different popular techniques such as non-chlorinated brake cleaner, isopropyl alcohol, sanding, burning oils off through "baking", and concluded that not enough brake power was restored and strongly recommended just buying a new set of pads and rotors, noting that the time spent cleaning was not worth the money savings compared to the cost of the new parts. One article also noted that the brake pad material could separate from the pad's backing plate when heated to high temps.


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## NordieBoy (Sep 26, 2004)

Could separate. Sounds like they didn't though.
Torching them takes 5min if you're slow. To me, that's cheaper than new pads and rotors...


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## mxxmikexx (Oct 17, 2015)

ive tried everything. new pads, new icetech rotors, torching, brake cleaner, alcohol. i have a stack of pads ive gone through with 2-3 rides on them until they are unsalvageable . sometimes torching can save a set, but not always. 
and thats the thing, the bucksaw isnt even getting ridden an any crazy,muddy,etc.
i use it primarily to take the dog running on limestone trails. never happens with the front xt only the rear. i guess process of elimination points to something going on with the caliper. maybe ill just throw another hundo at the bike and try another set. because ive certainly spent that much in pads so far... lol.


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## NordieBoy (Sep 26, 2004)

I've spilled fork oil all over motorbike pads and rotors and brake clean on the rotor and torching (well, setting them on fire with brake clean  ) the pads and they were like new afterward.


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## freewheelingf (May 24, 2019)

Solved.

I tried everything I came across to stop my XT rear brake squealing. I checked and reset alignment, I sanded the pads, I changed the pads, I changed the rotors and I made sure that I bedded the cleaned/new pads in. I checked the calipers were not leaking.

Finally I cleaned all oil from my chain and sprockets and torched my pads with a blow torch until they no longer caught fire (presumably once all oil residue had been burnt off). I then lightly sanded pads and disc. I lubed my chain with a drop on each chain link of quality synthetic lube.

My rear brakes have been perfect ever since. My theory is that oil from my chain/sprockets has been contaminating the pads. It might explain why others have found torching their pads has been a relatively short term fix.


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## gastonbx (Oct 15, 2009)

Solved this migrating to Shimano G02a Resin compound when in the city, removing organic pads and reserving them for mountain usage. No more problems and confirms the ones with pad-related theories, discarding the oil leakage suspition.
Pads are:
https://www.bike-discount.de/en/buy/shimano-disc-brake-pads-g02a-resin-437787


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## rfxc (Oct 18, 2004)

Wife & I switched to Sram brakes in Feb 2018... two sets of Levels, two sets of Guide RSC's... no problems at all, even after bike sits for months. I used to bleed shimano brakes couple times/year at min, and replace or bake pads many times/ year. Sram brakes 16mos going, just replace pads as they wear down, nothing else to worry about.


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## Cleared2land (Aug 31, 2012)

rfxc said:


> I used to bleed shimano brakes couple times/year at min...


Care to expand on the necessity of bleeding at these intervals?


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## rfxc (Oct 18, 2004)

Couple times per year because I had 8+ sets in my household. Not always a necessity but trying to get consistent lever feel/bite point, doing it because my wife would say "this one feels weird please bleed it" etc. Sometimes I'd do it, sometimes I'd pay a shop if I was busy paying the bills, sometimes I'd pay the shop to do it because I didn't want my wife to blame me for odd/inconsistent brake feel.

In the sport 20 yrs, bleeding my own brakes for 15+ years, advocated for Shimano brakes on multiple occasions, for my cat 1 xc and big mtn enduro racing... The last 18mos on sram brakes (now 6 sets in my household) have been my most "tinkering free" experience with brakes yet.

So glad I'm not playing the game of removing and baking pads as described in the early posts on this thread.

Thank you, sram level & guide.




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## MTBMILES (Dec 27, 2007)

I have the same thing going on(XT and XTR) and for me I just ran down a big hill and did the basic "bedding in" procedure and the squealing went away and the power came back on hundred percent.
I could not find any signs of oil residue. I am looking forward to using a torch though.

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