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Thread: Leaking Master Cylinder

  1. #1
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    Leaking Master Cylinder

    I have a 96 R1100R with 17k on it and with ABS. I've only had it since April so I'm still learning about it. I just noticed that the front master cylinder is starting to leak (the joy of buying a used bike). Is this rebuildable? If so what is necessary. Since it's ABS what are the tricks to bleeding the system. TIA.

  2. #2
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    Lightbulb Master Cylinder Rebuild Kit

    Rundel, Hello, This is not an un-common problem. My friend had the same thing happen on a 97 R, he could not find a rebuild kit and replaced the master cylinder. I have recently heard a rebuild kit is available, the part number is: 32-72-2-332-037.

    As far as bleending the brakes, even though it's ABS, bleed as normal via the valves on the calipers. However, it is possible to get air in the ABS modulator. And the only way to get it out is to bleed from the modulator bleed valves, under the gas tank. If your brakes feel normal after repairing the leak and bleeding the system, don't worry about this. Good luck and good riding!
    Vincent
    1998 R1100RT
    1963 R60/2

  3. #3
    palberini
    Guest
    I just replaced mine on a 96 R1100RT, 16k miles. Same problem, the lever start feeling spongy and thereafter started leaking. No particular problems in replacing the part, except for taking down the heated grips.

    I couldn't find a rebuilt kit, so I got a new part ($200). Better use a vacuum bleeder ($20) to get the air out. Good luck.

  4. #4
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    update

    As an update, I disassembled the master cylinder while still on the bike. The area behind the rubber outer seal was crudded up. I was able to pull the piston and the cylinder wall was pitted from the unchanged brake fluid. I attempted to resurface with a 3M scotch pad but it wasn't agressive enough. I then resorted to more power and got out the dremel tool. I used a small drum sander to smooth things out and then used felt polishing cones and wheels to slick things up. I then cleaned out the cylinder and re-assembled. The seals on the piston looked good.

    As of today, four days latter, it has weeped a little but that may be the seals re-seating. After a ride tonight, no leaking. We''ll see what happens.

  5. #5
    Hear that ticking sound? jnerges's Avatar
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    Sorry to light up an old thread. Where did you get the new Master Cylinder? From a dealer?
    Thanks,

  6. #6
    GEEZER lsouth3's Avatar
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    Master Cylinder

    I got mine new from Beemer Boneyard. Then I had the old one rebuilt locally with a stainless steel lined cylinder. Haven't needed it yet but the rebuild cost about 80 bucks.
    Lee - The older I get the better I was
    1994 R1100RSL, Black. 1994 R1100RSL, Silver Pearl and a "new" 2001 R1100RS, Red!
    Treat all others with politeness. Not because they are nice but because you are.

  7. #7
    aapasquale
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    there are kits you can buy to overhaul these brake master cylinders and they are pretty straightforward to repair. did mine last winter with great results and I am a newbie at this stuff

  8. #8
    . AntonLargiader's Avatar
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    Wow, this is an ancient thread, but I have had an article describing the in-situ overhaul on my website for about as long:

    http://largiader.com/tech/r11mc/

    Just did this procedure again last week.
    Anton Largiader 72724
    largiader.com bmwra.org

  9. #9
    aapasquale
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    Quote Originally Posted by AntonLargiader View Post
    Wow, this is an ancient thread, but I have had an article describing the in-situ overhaul on my website for about as long:

    http://largiader.com/tech/r11mc/

    Just did this procedure again last week.
    Hi Anton
    it was your article that got me through the rebuild last winter. May be ancient, but still clear and helpful.
    Thanks,
    Tony

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