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TRP Hy/Rd Bleed Problem

kinderkriskinderkris Posts: 3
in Workshop
So, I tried bleeding my Hy/Rd caliper last night for the first time after 3 years of use. I followed the official video guide exactly as advised...



All seemed to be going well, but now the lever pulls all the way to the bars and the pistons refuse to move. There is no resistance at the lever. The fluid was flowing out freely, clear with no bubbles. I bled them a second time this morning but no difference.

Any ideas?

Posts

  • oxomanoxoman Posts: 11,176
    edited March 2020
    Sounds like you've got a stubborn air bubble or a seal gone. Any oil appear to be leaking from anywhere. As these are mechanical to hydraulic is it possibly the cable is slipping at the caliper or broken. TBH they're normally bombproof.
    Too many bikes according to Mrs O.
  • smethleysmethley Posts: 45
    edited March 2020
    As the previous poster implied, unless you managed to break seals front and/or back, then either you have air (spongy lever feel) or you have a leak (drips will be visible), or it's not a hydraulic problem but a cable problem - in which case look for lost motion (you pull the lever, but the brake actuator at the caliper doesn't move).
  • kinderkriskinderkris Posts: 3
    I have no oil leaks and it's not a cable problem as I'm manually pulling the actuator arm all the way in. As a last resort I might try bleeding with the caliper off the bike, moving it around whilst I do so to try and remove any trapped air.

    If that doesn't work I'm going to admit defeat and downgrade to the mechanical TRP Spyre. This is for my commuter which needs to be reliable all year round.
  • smethleysmethley Posts: 45
    Good idea, trapped air can sometimes be very difficult to remove without re-orienting caliper.
  • kinderkriskinderkris Posts: 3
    UPDATE - moving the caliper around whilst bleeding off the bike did release some trapped air. The good news is that the brake is working again, the bad news is that I now realise I have a sticky piston that is hardly moving. Currently trying to get it moving...
  • skeetamskeetam Posts: 175
    edited March 2020
    kinderkris said:

    UPDATE - moving the caliper around whilst bleeding off the bike did release some trapped air. The good news is that the brake is working again, the bad news is that I now realise I have a sticky piston that is hardly moving. Currently trying to get it moving...


    Zip tie the good one in so the stuck one should start to move when you pull the lever (path of least resistance). Get some cotton buds to clean around the edges of the piston when it moves out. Should be OK after that.
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