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  1. #1
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    XTR-966 Brake Lever Issue - Slowly bottoms out when brake applied

    I have a set of XTR-966 shifter/brake levers on my xc bike. They're getting on a bit, and the rear brake is having an issue. When you pull quickly on the brake lever, it does activate the brake, but not that hard, and then as you continue to pull, the lever keeps on traveling and bottoms out.

    I've tried bleeding the brakes again, and they're fine (I have bled a dozen sets of Shimano brakes over the years, and am pretty sure it's not my bleed method).

    All I can think of, is that the lever piston has a gap between itself and the wall, so if you push quickly, it'll brake, but then the fluid begins to leak back past the lever piston into the reservoir, and the brake force decreases.

    1) Has anyone seen this too?
    2) Is there a solution? I've not looked at pulling it apart yet (and infact the bike is not accessible to me right now, so I'm just trying to get some info and formulate a plan before I get back to the bike).

    Thanks

    XTR-966 Brake Lever Issue - Slowly bottoms out when brake applied-shimano_xtr_966-965_shifterbrakeset.jpg
    Attached Thumbnails Attached Thumbnails XTR-966 Brake Lever Issue - Slowly bottoms out when brake applied-str-brake-lever.jpg  


  2. #2
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    Reputation: gmats's Avatar
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    Aloha, yes, this sounds like the seals on the master cylinder's piston is leaking. This happens on cars too. The master cylinder will need to be rebuild with new seals. Good luck with that.

  3. #3
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    Reputation: ColinL's Avatar
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    Quote Originally Posted by gmats View Post
    The master cylinder will need to be rebuild with new seals. Good luck with that.
    Agree it is the cylinder... and if this is a suggestion to replace the brake, I would agree with that as well. AFAIK a rebuild kit doesn't exist, so only Shimano could service that.

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