# Howling brakes on Ventana



## Trails4Two (May 12, 2008)

Since last fall we have had issues with our rear brake howling on our El Conq. Not just a little noise either - a full frame vibrating, hand-numbing vibration. Kind of like grabbing a live wire. It is a 2006 Ventana El Conq and we have had no issues with brake noise until last year. The brakes are Magura Louise (stainless cable) 190mm rear (front brake is silent). Before I get roasted, here is what we have tried so far:

1. had a shop re-face the mounts, clean the caliper, check alignment, new pads (EBC): this worked for about 5 rides then it got bad again.

2. Tried new pads(EBC) again. Lasted one ride.

3. Checked all pivot bolts, looked for cracks in swingarm.

4. tried swapping the rear rotor/pads(Magura)/adapter with our other set of magura Louise that live on our Cannondale: still just as noisy.

Up until now it had been simply a massively annoying noise, but after talking to Theresa at Ventana, I've been warned that this kind of vibration can lead to swingarm failure.

Any ideas?


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## phill77 (Aug 31, 2008)

No ideas, but my '10 ECDM has done the same from new with A 203mm Louise on the back. I don't think mine is quite as severe a vibration as yours, but as soon as you mention swingarm failure it makes me nervous!

One thing you haven't done which I could easily try is another manufacturers disc. Will do that over the weekend and see if it affects things. 

Phill


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## Trails4Two (May 12, 2008)

One of my next steps is to cobble together an bb7 set up for the rear to see if that helps.


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## PMK (Oct 12, 2004)

My first guess, the disc is too smooth. Second guess is bleed it with a Mityvac and run a lot of fluid through the system. Also, fine dust, soap residue, or crud have made my other brakes and truck shudder.

Before you do this, ensure the caliper has no leaks at the piston. Clean everything with chlorinated Brakleen. Remove and wash the pads, you can even clean your other ones and they will be fine.

You might also ensure your left side hub bearing is good / tight / not needing adjustment if adjustable.

Best of luck with it. When we ran Maguras, they had moments.but seldom shudders, and once properly bled were very powerful, with a rock hard lever.

PK


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## Ted (Jan 29, 2004)

You might also try using a Dremel to chamfer the edges of the rotor cutouts that the pads see. This has helped quiet down my brakes but they were not as bad as yours seem to be.


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## Trails4Two (May 12, 2008)

*Aha!*

I think I found the culprit! I have a sticky piston in the rear caliper. It hid from my efforts to detect it by only sticking part way through it's motion. If I looked at it while the rotor was on, it was very hard to see, but when the wheel was off, I could see that the pads were not meeting in the center of the caliper. Unfortunately, while trying to free the piston up I burped fluid out of the line...now I have to wait until the shop opens tomorrow to test out this solution.


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## Grno (Feb 4, 2010)

how did you manage to knock fluid out of the line while freeing up the piston?


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## Trails4Two (May 12, 2008)

I had foolishly removed the pads before working on it. Without the pads in there, the piston was able to move too far out. Fortunately I didn't pop the piston all the way out and was able to get it retracted again (minus a bit of fluid)


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## PMK (Oct 12, 2004)

Really, what I would do is take both calipers apart, clean everything in mineral spirits. Flush the line and master cylinders Ensure it's dry. Assemble the piston into the caliper with silicone grease, and bleed it solid with fresh fluid.

Do yourself a favor, get a bleed kit. You can use the syringe but it is much easier with an inexpensive Mityvac brake bleeder. It will take two people, sound familiar? 

I do not use Magura fluid, and definitely don't use the mineral oil from the drug store. When I bled the Stainless lined Louise set on our ECDM I used Showa SS suspension fluid. Low viscosity and a lively lever. You can also use Mobil 1 transmission fluid.

When those brakes are bled correctly, they are more solid at the lever than the Brembos on my KTM 250. 

I loved that 210 mm front brake, unfortunately they don't make the Fox 40 adapter any longer. So, we cautiously ride with our BB7's.

Glad you found the problem.

PK


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## Ted (Jan 29, 2004)

PMK,

Please explain how you use a Mityvac to bleed Magura brakes. And, which model of Mityvac that you are using. I am currently using the Magura bleed kit on my Louise FR and it is difficult to do it even with two people.

Also, don't your alternatives to Magura Blood overheat?

One more: How do you pop the pistons out of the calipers? Are they hard to re-insert?

Sorry for all of the questions. I am just looking for an easier/better way.

Ted


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## PMK (Oct 12, 2004)

Ted said:


> PMK,
> 
> Please explain how you use a Mityvac to bleed Magura brakes. And, which model of Mityvac that you are using. I am currently using the Magura bleed kit on my Louise FR and it is difficult to do it even with two people.
> 
> ...


Ted, I pulled up the Mityvac webpage. My bleeder which is not that old, maybe 7 years, must now be an older style. The Mityvac I own not only does vacuum bleed but has a pressure port also. I am not sure the new tools have this pressure capability.

Regardless, the main reason for using the Mityvac is the ability to push more fluid through at a better pressure. It is also nice to have the ability to degas the fluid under vacuum before bleeding. Degassing will remove most if not all of the micro sized bubbles you don't see.

In regards to popping the pistons, every disc brake I have worked so far these were able to be removed. Magura rim brakes no way. However, I have never fully removed the piston from our Louise Stainless Steel hosed versions.

I normally give them a shot of compressed air while directing their direction into a rag. Of all the disc pistons I have removed, none were difficult to install, just took some care to ensure they were straight when going back in.

I have never overheated my fluids, but then again I am not descending for miles. Magura fluid is basically a petroleum oil. FWIW, on my KTM 250 dirtbike, it has a Magura hydraulic clutch. It is supposed to run the same fluid as the bike brakes. In that application the Magura fluid works but the lever feel is slightly sluggish, adding to arm pump. I run Mobil 1 transmission fluid, to match the gearbox fluid in the event the slave cylinder seal failed. Never a problem during any ride in the Florida heat. Also, a car transmission runs very hot and the Mobil 1 holds up. The Showa fluid is less viscosity. This is a fluid approved for a rear shock on a motocross bike, they get seriously hot with no issues.

In regards to using the bleeder, most often I attach the Mityvac bottle to the pressure port. Start pumping fluid up from the caliper towards the master cylinder. Jeanne catches the overflowing fluid. She also will cycle the lever as fluid is flowing AND move the bars to alter the angle the master cylinder is positioned. ALSO, I reposition the top of the master cylinder horizontal for bleeding before starting to flow fluid.

It's a pain to bleed brakes and worse to have them act up on a road trip. This is one reason why I have all of the tandems on BB7's with the same Avid levers. For spares I bring an extra caliper, new pad set, and long inner cables. Anything else I can get easily in a local shop while on the road. And yes I have forcefully removed a brake hose and sprayed fluid everywhere, it was with Magura rim brakes and the ride was over. Also, I went over the bars on my Turner while on a work trip with my bike. Broke a Magura lever. No shop had one and delivery time would be 1 week. I had Jeanne remove the lever and send it FedEx Saturday delivery with some obviously needed work supplies, crisis averted.

PK


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## PMK (Oct 12, 2004)

Curious if he ever got this fixed...
PK


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## Trails4Two (May 12, 2008)

*Waiting*

I called both Ventana and Magura. Theresa at Ventana sent me a nice checklist of things that can cause howling that Sherwood had worked up with the Magura folks. This led to the find of the sticking piston. When neither I nor my shop could get the piston to free up ( it would free up for a while, but after sitting a few hours, it would stick again) I called Magura USA. After a three minute conversation they offered to send me a new caliper. I'm now waiting for it to show up. Then swap, rebleed, put on the new pads I have, and go try it out.


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## She&I (Jan 4, 2010)

My newly built Ventana single has the same issue; my LBS tells me two other Ventanas had the same problem. They claim it's simply the engineering and stiffness of the rear triangle, which tends to resonate unduly. We're trying to rectify the problem without shotgun or temporary solutions, so it may take some time. I'll be back on it in Aug and will report findings. Cheers 

Mike


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## Trails4Two (May 12, 2008)

*Infor from Ventana*

She& I, what brakes are you using? I just got the new caliper mounted and we did a 15 mile ride. Unfortunately, it was the most level ride I've done around here so we don't know if it fixed yet.

Here is a nice checklist Theresa sent me:

Here's what Sherwood put together for another customer. Take a look at it and let me know if you have any questions.

The frame does not create a resonance, it reacts to a vibration that comes from the brakes and can amplify it when manifested at a frequency close to that of the resonant frequency of the frame.
The squeal starts and finishes with your brake setup (specifically the pad/rotor relationship.) Once a squeal starts at the brake pad/rotor interface it is not possible for any frame to damp it out adequately. Don't buy any more pads or rotors, but go through the steps listed below to resolve your squealing issues.

There are several causes for brake squeal and the squeal always starts at the pad rotor interface:
1. Improper alignment

2. Uneven braking pressure

3. Contamination of the braking surfaces

4. Grooving or warpage of the rotor

5. Uneven pad wear

Alignment: Alignment is critical as the pad and rotor faces must come into contact simultaneously and at the same time front-to-back and perfectly flat. Check both in the stand and when sitting on the bike to account for any axle deflection when loaded. Adjust, check, re-adjust, check again and repeat until this is perfect. Check that the fully retracted gap is the same between outside pad/rotor face, and inside pad/rotor face (except on single sided mechanical brakes.) If the relationship changes when sitting on the bike adjust it while loaded. Most brakes allow for a mm or so of pad displacement so make sure the pistons are centered in their stroke when engaged for best results.

Braking pressure: To equalize pad pressure, check that both pistons extend and contract easily. In dirty gritty environments pistons can become stuck and must be broken free to perform correctly.

Contamination: Remove the pads, check for discoloration, grooving, uneven wear, and nicks or gouges and sand the faces on a flat surface with 120gr sandpaper until clean pad material is revealed (if the pads are too thin at this point replace them.) Notes: Never replace a rotor without cleaning the pads, or pads without cleaning/resurfacing and aligning the rotors. If you frequently wash your bike, all water must be removed from the rotor and pad surfaces or you risk contamination that can boil out of the pad/rotor surfaces once the brake becomes hot under load.

Rotor: On the bike, check the rotor for discoloration, grooving and warpage. Spin the wheel and reference the rotor face for lateral movement and align with a gloved hand until it spins flat and true. Sand the rotor faces until all discoloration and grooving is removed. If the rotor is warped or grooved beyond repair, replace it (reference note above.)

Pads: Uneven pad wear can be attributed to improper alignment and/or a stuck piston. If the wear is significant, replace the pads, clean them and clean and align the rotor (reference note above.)

Once you are convinced this is completed you must now go through a proper pad/rotor break-in procedure. Our break-in procedure is 20 brake loading sequences starting with very light brake pressure on the first couple of applications progressing to full on wheel locking for the last couple. If at any time a brake squeal is detected, and it does not dissipate in a few more steps in the break-in sequence, repeat the alignment procedure.

One final note: There is a spray on solution called Swiss Stop that claims to eliminate brake squeal, but I have found that it does not work unless all of the above has been addressed first which makes it hard to evaluate any actual performance benefit.

Once a squeal starts it can be amplified by several things:
1. Loose axle bearings

2. Loose rotor bolts

3. Loose caliper mounting hardware

4. Worn/sloppy suspension bearings

5. Loose wheel skewers

6. Frame resonance at certain brake vibration frequencies (what you feel in the bars and seat)

All of the above issues should be checked and addressed to get maximum performance from your bike, but they will only mask a brake pad/rotor interface problem. For example, a loose part will not make your brake squeal, but a squealy brake can cause all of the above, in addition to making your bike no fun to ride, and ultimately accelerate fatigue relate breakage of your frame.

Hope this helps,

Sherwood


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## She&I (Jan 4, 2010)

Thx loads for that, T42. I forwarded it to my guys. 

Formula R1/stock (non-org?) pads/Formula 180 rotors. 

Thx again T4 ND all for bringing this to the fore. 

Mike


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## Trails4Two (May 12, 2008)

Glad to help. I had thought it was just an annoyance until I talked to Theresa and she told me about the increased wear on the swingarm from the vibrations. Our brakes were quite for two+ years before starting in with the noise. I think that Ventana frames do tend to amplify the sound a lot.


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## PMK (Oct 12, 2004)

Bike frames overall are a huge tuning fork...yes, if the pads can't grab and hold the disc, the shudder can be very destructive.

PK


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## She&I (Jan 4, 2010)

Update:

We were able to quiet the noise tremendously by simply ditching the Formula rotor. We used a Galfer Bicycle Wave® rotor in rear. There is some howling on occasion during a ride, but nothing like the consistent howling/vibration previously.

Additionally, the front brake is now taking up the howling noise, albeit not quite as loud and definitely not as vibrating. We're going to replace that rotor as well, likely with the same Galfer we used on back. If we get the results we think we will, that should point to the rotors as the main source of noise.

I have Formula The One brakes on another bike, and had some noise issues with them running the stock rotors (nothing like the Ventana). Have since switched to Magura rotors (Storm rear, SL front) and am enjoying a much quieter setup.

Mike


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## dodger (Feb 10, 2004)

*Same ECDM problem here*

Ours is maybe an 04? Have had the same issue on the rear since day 1. Tried both an older XT 756 brake as well as an Avid Juicy 7, both with sintered pads. Neither ever had any issues on prior single bikes.

The only thing that addressed the vibration was going to organic pads. Unfortunately, they offered no where near enough stopping power for the long, steep trails we take it on. I was close to trying to figure out how to fit the rotor and brake from my KTM on it. That rotor is probably 3-4x thicker and no way it would vibrate.

I too had contacted Sherwood and tried everything on his list.

Gave up and learned to live with the vibration...until the entire rear triangle destroys itself someday I'm convinced it's a problem endemic to the Ventana. That said, it's still the best tandem out there and hands down the only one worth of anything gnarly.


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## She&I (Jan 4, 2010)

Thanks for bringing this to mind again, dodger. This really seems to be an issue with Ventana FS frames.

The problem on my Ventana single is more pervasive than I had thought. So much that after trying several things we have simply ditched the Formula brakes and put on XTR. The problem is still not completely absent even with the XTRs, but I need to do some more experimentation to try to dial it in. (I've been laid up for some weeks now.)

Honestly, if I had known in advance of this issue I would have refrained from taking on a Ventana frame. It's been a disappointment. It pains me greatly to state this, as I love every other aspect of the bike. Should probably be posting this in the Ventana forum seeing how mine isn't a tandem. FWIW.

Mike


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## Okayfine (Sep 7, 2010)

In another thread on this topic, I posted of my change to organic from sintered pads. This eliminated the vibration problem. I've also had differing quality pads in the back, from OE Hope (great) to A2Z (meh). There may still be hope (ha!) for dodger by experimenting with different pad brands to find ones that bite enough.

ECdM, Hope Mono 6.


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## dodger (Feb 10, 2004)

Right you are. This was years ago when I experimented but I recall trying at least 2 different brands and 3 different compounds, even mixing and matching with differing pads for the set. Some were downright dangerous, some 'only' required 4 finger braking! 

We don't ride it much these days so I pretty much gave up. Somebody with more conviction might have been able to make it right.


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## PMK (Oct 12, 2004)

Recently on the tandems I have noticed that over time, the sphereical ball and cup alignment design of our Avid BB7's creeps as bit. While we do not have many shudder issues, the calipers do come out of alignment.

I plan to have a look at either machining spacers from 7075 aluminum , or seeing if a series of stacked washers the same diameter as the OEM parts will stabilize the caliper further.

For those with brake shudder, are you able to skid the rear tire on a trail with decent grip? Unless your stoker weighs 500 pounds, if the rear can't clamp tight enough to lock the wheel, there is a brake problem. Air in the hydraulics, crud on the pads, disc or both, brake disc is too smooth, either worn or delivered smooth.

The Louise hydraulics we had were very strong. Sometimes even violent under last second hard braking.

Best of luck with it.

PK


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