# Shortening and Re-Bleeding Hydraulic Lines



## Guest (Apr 20, 2007)

I have a set of 970 XTR Hydraulic brakes I pulled off of my large Specialized Epic to put on my wife’s extra-small Titus Racer-X. Needless to say the rear brake line is about a foot too long. I need to shorten it and re-bleed the brakes. I am perfectly comfortable with the “topping off the brake fluid” kind of bleeding but not a complete from scratch bleed. I’m really worried about getting all of the air out of the system. Any instructions/pointers would be great. I'm also wondering how much hydraulic fluid is necessary to pull this off.

bm


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## mtbhermit (Mar 8, 2007)

I've shortened both my hydro lines on the Shimano XT brakes. It was not as scary or hard as I thought.

Firstly I'll assume that the XTR is very similar to the XT.

If you do a search on XTR hydros a thread should come up which has some instructions in it.

Basically you can take the brake line out of the lever end without loosing any fluid. You may loose a drop or two but it won't piss out like you imagine. Think of a straw with your finger on it, that's why the resevoir won't loose any fluid.

You need to have a new olive and insert ready - should be very cheap to buy at your LBS.

Basically you undo the nut & pull the line out.
Cut it wherever you have decided to. This is when hydro fluid comes out of the cut hose section so have a rag or something ready - it won't be a huge amount.
Slide the olive onto the hose.
Put the new insert (or is it called a barb?) into the hose. This is the trickiest part I have found because it's hard to get the insert to go in, I used pliers with a cloth to hold the hose & a tire lever to push down on the insert. Just found it hard to do without damaging the hose with the pliers! So take your time with this step you may need some patience!
Once that's done then you insert the hose back into the lever & do it up.

Your brakes may not even need bleeding at this point! If they don't feel as good as before then do the bleed as you normally would.

In regards to hydro fluid I'm guessing that one shimano bleed kit is enough to do both lines from scratch.

I did my front brake without a hitch. When I decided to do the rear the hose wouldn't pull out of the lever so someone suggested doing it back up a bit and squeezing the lever a couple of times. After that I undid it again and it came out a bit easier. I also slightly damaged the hose when inserting the barb but nothing detrimental at all.


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## Guest (Apr 21, 2007)

Awesome Pointers mtbhermit. Thanks!

bm


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## Mike T. (Dec 30, 2003)

What needs to be added is that when the line is disconnected, hang onto it with a death grip. If you let it "flip" it will spray out a few drops of fluid and then you will have to bleed. Go so far as to get a helper to hold it if need be. Cut square and clean with a sharp (new?) boxcutter blade against a block of wood. And DON'T let anyone sqeeze the brake lever!


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## mtbhermit (Mar 8, 2007)

You could put a zip tie around your bar area to slot the line in when you need free hands to grab tools etc.

I wasn't so careful with my last attempt and didn't loose sufficient fluid to require a bleed at all.

Another tip. I had a real hard time pulling the line out of the lever after it was undone. Someone suggested to do it up a bit and squeeze the lever to help it release. It worked like a charm, the line came out a bit easier after that. Mind you it can also lead to loosing a few drops of fluid basically because the line isn't tightened all the way in, and I did notice a few drops come out of the lever area after. Even still brake performance & feel is the same as before without doing a bleed.

Oh and another thing I realized recently because someone else posted on the topic. The front brake line is all plastic, whereas the rear has a wire sleeve. So if you are shortening the rear it may be a little harder to cut than the front. Depends on the brake line that XTR uses I guess.


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## eman2 (May 3, 2004)

*wait a second*

if you pull the hydro line from the lever, isn't the fluid in the lever reservoir going to just drip out?

A few things to add above. A new barb is definately needed, a new olive might not be - depends on how much the bolt was screwed in. I have reused mine -- I check that is was leak free by clamping on the lever overnight -- no leaks means it is okay to me.

Also, put a dab of grease on the olive.

happy bleeding.


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## mtbhermit (Mar 8, 2007)

eman2 said:


> if you pull the hydro line from the lever, isn't the fluid in the lever reservoir going to just drip out?
> 
> happy bleeding.


Sounds like you've done it before, was it with Shimanos or something else?

I did forget to say that I leveled the lever out (like you would when bleeding) just in case. But no, didn't get any fluid loss from the lever at all with the first I did and only a drop from the 2nd (due to pulling on the lever blade to get the line to pop out easier). Even with the reservoir the same straw principle applies, as long as you don't undo the resevoir cap it shouldn't leak or not significantly anyway.

I was pretty surprised when told this as well, it's absolutely great! Although after finding out how small the hole in the barb is then it's more understandable that a hole that diameter in the lever housing would probably have even more resistance to leaking than something bigger.


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## eman2 (May 3, 2004)

*That was just my thought*

I just thought the lever fluid would leak out -- but if you have tried it and were successful then great -- I will know for next time. I have spent a lot of time messing with my XT 755's and I have shortened the lines but I always just sucked the reservoir dry before loosening up the hydro line. Good info for the next time.


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## Mike T. (Dec 30, 2003)

eman2 said:


> I just thought the lever fluid would leak out -- but if you have tried it and were successful then great -- I will know for next time. I have spent a lot of time messing with my XT 755's and I have shortened the lines but I always just sucked the reservoir dry before loosening up the hydro line. Good info for the next time.


Hydraulic brakes - car and bike - work on the "finger over the end of the straw" principal. If you leave the cover on the master cylinder then fluid won't run out of an opened line.


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## El Mojone (Jun 23, 2008)

I've done a few. It is a piece of cake. Level the res, use sharp to cut hose, insert barb, slide on olive, push hose until fully seated tighten. You are done, and if you were half way careful no need to bleed. I haven't had to bleed yet.


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## Cracka (Jul 21, 2006)

http://bike.shimano.com/publish/con...downloadFile.html/02) Brake Hose Trimming.pdf

I just followed the procedure at the above link. Took 15 min. and worked great. After reassembly, the lever felt very squishy until I cycled it 50 times or so. Now its solid as ever with no bleeding required. Too easy.

Bump.


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