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What have I done to my brakes?

skiffyskiffy Posts: 84
edited May 2016 in MTB workshop & tech
Not sure if I've made a bit of a schoolboy error here. I have XT hydraulics and I confess I've never worked on them, don't know how to bleed them etc, just something I've had done as part of a service.

Recently my front brake had exhibited a sticking point halfway through the stroke, I needed to apply a bit of pressure for the piston to suddenly move. I figured there may be debris or corrosion in the piston. So I took the wheel off, pulled out the pads, cleaned inside the caliper, then squeezed the lever to expose the pistons (one barely moved, the other moved fully). I cleaned around the exposed piston and then pushed it back in with a plastic tyre lever. Took a little force (not too much) to get it moving but then it retracted fairly easily. However now when I pump the lever... nothing, no pressure at all. I haven't bled anything, there's no leak, could I have knackered an o-ring or something?


  • Rossf2705Rossf2705 Posts: 6
    The pistons in the Calipers arent retained, if you pump the brake when there is nothing in there is can push them out too far, did you notice any brake fluid come out? IMO youve lost fluid out the system and they'll need bleeding. Sounds like you have a stuck piston as well, they should both move.
  • skiffyskiffy Posts: 84
    My next move was going to be to hold in the moving piston and squeeze the lever to push the sticky one one out but now there's no pressure to do so. Maybe I did push it too far but didn't notice any seepage.
  • oxomanoxoman Posts: 11,747
    As with all thing's of this nature use youtube video clips for how to bleed hydraulic brakes etc.
    Too many bikes according to Mrs O.
  • skiffyskiffy Posts: 84
    Will replenish/bleed and try to free up the sticky side. What's best to use to lube the piston? A dab of the brake fluid or some grease? I also have some spray lithium grease.

    If it turns out to be knackered anyone got a spare...
  • cooldadcooldad Posts: 32,599
    A dab of brake fluid with the pads removed. Don't spary anything near them.

    And make sure you use compatible fluid - Shimano use mineral oil not DOT fluid.
    I don't do smileys.

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  • skiffyskiffy Posts: 84
    yeah I've ordered an Epic kit.
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