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Shimano hydro brake lever glitch!

Discussion in 'The Shop' started by talkinghead, Apr 19, 2012.

  1. talkinghead New Member

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    My rear brake is acting a bit strange. When I apply pressure there is a bit of resistance then it releases (sort of a bump) and the brake works as normal with good modulation. This will repeat most, but not every time I grab the lever. If I "pump" the lever several times in rapid succession it stops doing it for a few strokes. Also, the lever doesn't return to the full open position unless I "pump" it.
    The disc is not dragging, and is well centered.

    Any ideas?

    BTW, the search function didn't provide an answer...
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  2. oldfart Active Member

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    Clean and bleed?
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  3. talkinghead New Member

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    By "clean" do you mean to dissassemble everything, clean, and re-assemble? Or, is there a specific area that might cause this "sticking" phenomena?
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  4. oldfart Active Member

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    There are probably some web instructions out there, but essentially you remove the pads and hold on piston in and pump a little. Clean what is exposed and push the piston back repeat on the other piston. Take the lever pivot apart and clean in there just in case there is something in there that is catching. It is really hard to diagnose from a description because there can be a number of causes. If the pistons are stuck that might explain why the lever does not return. Or maybe the fluid is contaminated or low, or external dirt in the lever pivots. I would start with a detailed visual examination while you squeeze the l;ever repeatedly just to observe what the pistons are doing. Do they come out evenly and retract evenly?
    #4