Rear brake issue

BOOTHMEISTER
BOOTHMEISTER Posts: 19
edited August 2013 in MTB workshop & tech
Having been riding my Trek Fuel for well over year I have had no real issues with the brakes until recently. All of a sudden my rear Shimano XT brake just squealed aaaaaaaaaall the time and despite cleaning both the pads and disc and even sanding the disc to a flat surface again and bedding in it still never stopped.
In the end I replaced the rotor and pads for new pressuming that I had managed to get some lube on them or something. I bedded them in with plenty of hard stops and they worked fine for about 50 mile but now they are squealing again. I have put lube nowhere near them and they were bedded in.
I found an article that suggested placing the pads in a blue gas flame to burn of an contaminants and to my surprise a significant amount of oil did appear to come out of them? I then cleaned the rotors with some rubbing alcohol and its has stopped the squeal. The problem now is that my rear brake is really poor and has no grab at all. I can just about lock up the rear wheel if I stand up whilst doing so. I bedded them in too so expected them to get better after a bit but it ain't happened.

I am at a total loss as to how to rectify this and at over £50 for a new set of pads and a rotor I do not want to splash out a second time.

Any advice people?

Thanks, Chris.

Comments

  • montyburns56
    montyburns56 Posts: 70
    You could try rubbing your pads with some rough glass/emery paper as sometimes the surface can get glazed and lose it's abrasiveness.
  • YeehaaMcgee
    YeehaaMcgee Posts: 5,740
    What do you wash your bike with? how do you wash your chain? What general bikey maintenance do you do?
    My photos
  • BOOTHMEISTER
    BOOTHMEISTER Posts: 19
    I wash my bike with some Muc Off and hose down. For the chain I use some light oil which I apply then remove the excess with a cloth. I also use GT85 for the shocks but I apply that to a cloth first to avoid over spray. The bike is well maintained and pampered after most outings.
    I have also rubbed the pads down with some wet and dry paper.
  • YeehaaMcgee
    YeehaaMcgee Posts: 5,740
    Could be (and invariably is) any of those things getting where they don't belong.
    If it's not that, then if may be some oil getting past the calliper piston seal. The chances of that are slim, but not impossible.

    Incidentally, when you replace the pads, there's no need to replace the rotor. Clean the rotor with isopropyl alcohol - nothing else - and replace the pads.
    My photos
  • cooldad
    cooldad Posts: 32,599
    Brakes squeal sometimes. Live with it.
    Or ride through some muddy water - always seems to cure mine.
    Bikes make more weird noises in dry dusty weather than any other time.
    I don't do smileys.

    There is no secret ingredient - Kung Fu Panda

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  • The Rookie
    The Rookie Posts: 27,812
    A high pitched squeal isn't contamination, a lower pitched moan can be....and cleaning porducts are a common cause.
    Currently riding a Whyte T130C, X0 drivetrain, Magura Trail brakes converted to mixed wheel size (homebuilt wheels) with 140mm Fox 34 Rhythm and RP23 suspension. 12.2Kg.

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