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New second hand bike. Front brake squeals badly ?!

jack.murtonjack.murton Posts: 8
edited July 2019 in MTB beginners

I am new to mountain biking

I have a question about my front brake which doesn’t stop squealing.

I have tried all the basic stuff like disc cleaner, sanding the pads etc. Not really doing a lot tbh.

Can anyone advise what It could be.

I have Shimano xt brakes and rt81 discs




  • JBAJBA Posts: 2,713
    Have you tried realigning the caliper?
    “Life has been unfaithful
    And it all promised so so much”

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  • steve_sordysteve_sordy Posts: 2,131
    If it has oil on the pads, they are pretty much doomed. When you cleaned the pads, did you also clean the disc?

    The quickest way to fix this is to fit new pads, but assume that oil was the problem and clean the disc as well. Then bed them in properly.

    You may have been ultra careful and are convinced that you never got oil anywhere near the pads, but it can come off the road if you ride tarmac at all.
  • tom_howardtom_howard Posts: 792
    If it were me I'd just replace the pads and disc. Remove the chance of one re-contaminating the other, thus going round in circles, and both can be had reasonably cheaply
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  • swod1swod1 Posts: 1,639
    Pads are past saving by the sound of it.

    isopropyl alcohol on the disc and a new set of pads usually does the trick.

    Never experienced it on a front brake, usually rear brake I’ve had it on.

    Check calliper alignment, pads not central to disc will cause noise as well
  • kajjalkajjal Posts: 3,380
    As above remove the wheel from the bike, clean the rotor with suitable disc brake cleaner and also clean the brake calliper thoroughly with the same cleaner. Once you think they are both clean run a white kitchen roll over them to make sure, any black marks mean it is not clean. The thin groove where the rotor enters / exits the calliper tends to be where a lot of the build up is.

    Then fit new pads and you should be fine. The discs unlike the pads don't tend to absorb the oil etc. and can be cleaned easily enough.
  • Cheers for replies. After a long ride I’ve noticed the caliper is leaking from the bleed nipple. This has sin leaked onto my new pads and ruined the performance. The brake is a Shimano xt m8000. The bike shop seem to think it’s a new caliper but can the parts not be changed. Surely it could just be a washer/ o ring fail.
  • robertpbrobertpb Posts: 1,866
    Not if the thread on the caliper has been chewed by the nipple being poorly installed.
    Now where's that "Get Out of Crash Free Card"
  • The RookieThe Rookie Posts: 27,748
    Depends on why its leaking really!

    The nipple seals by a compression of its tip into the caliper body (there is no seal/washer/o-ring), if the caliper is damaged its a new caliper, if its the nipple then you need a new nipple!
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