hydraulic disc power loss

swampi101
swampi101 Posts: 210
edited June 2009 in MTB workshop & tech
yet more questions :wink:

ive had a promax hydraulic rear disc brake for about 2 months now, and up until this week the power has been great. but since i fitted a new rear tyre the power and responsiveness has dropped a bit, i have to pull the lever harder. it also squeaks a little bit, but not very loud.

its an open style lever, so no adjusters.

i was thinking the fluid could be contaminated, i was out in torrential rain and thick mud yesterday, could this be the cause?

Comments

  • nicklouse
    nicklouse Posts: 50,673
    more like that the wheel is not in the same place and the pads need to rebed in.

    changing the wheel is the only thing that you have done from working brake to non working?
    "Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
    Parktools :?:SheldonBrown
  • swampi101
    swampi101 Posts: 210
    yeah changing the tyre is the only think ive done apart from riding in rain and mud. im pretty sure the wheel is fitted back in properly, but ill take a look at it later
  • Matt 24k
    Matt 24k Posts: 186
    You probably just need to re centre the caliper on the disc but it may be an idea to take the caliper off and check that you haven't got a sticky piston. Remove the caliper, take out the pads and slowly pump the lever, you should see both pistons moving together. Be very careful not to pump the pistons out of the caliper. Only pump them out a couple of mill and clean around them with brake cleaner or warm soapy. Push the pistons back into the caliper until they are flush with the caliper body, replace the pads and bolt the caliper back on but not tightly. Next spin the wheel and apply the brake. Keeping the brake lever depressed tighten the caliper bolt fully and that should sort it.
  • Stephen-Hawking
    Stephen-Hawking Posts: 320
    Might just have picked some oily crap up on the disk / pads - hot soapy water is you friend here.
    Be happy, communicate happiness.
  • swampi101
    swampi101 Posts: 210
    cleaned off the pads and disc and the power is coming back again now :) thanks for the help.

    also i was wondering if levers are universal in the way they fit, e.g. could i fit these on hayes brakes:

    http://www.chainreactioncycles.com/Mode ... elID=32031
  • nicklouse
    nicklouse Posts: 50,673
    no those are for Formula brakes.

    you will need to find ones to fit Hayes (insert model here) brakes.
    "Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
    Parktools :?:SheldonBrown
  • swampi101
    swampi101 Posts: 210
    ah that sucks. just thought they might fit because they look kinda the same :(

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