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xt disc brakes brake fade

slmracingslmracing Posts: 26
edited November 2011 in The workshop
Well I am at a loss with this, the brakes are bled, calipers aligned, pads are new from disco brakes (sintered ) are they any good, the hoses are from disco brakes as well, the banjo type. When I set off to work on a morning they seem fine then after about 5 miles when braking they start to fade and squeal when stopping, I wonder if the caliper seals need replacing, any advice would be greatly appreciated :D

Posts

  • InitialisedInitialised Posts: 3,047
    I've had this happen in a car. Basically you've using them too much or they are rubbing allowing them to over heat. Try using copperlube on the back of the pads to help transfer heat from the pads to the calipers and reduce squealing. Or slacked them.
    I used to just ride my bike to work but now I find myself going out looking for bigger and bigger hills.
  • bails87bails87 Posts: 12,998
    I seriously doubt that MTB disc brakes, especially good ones like XT, would be overheating on a road commute.

    On steep MTB stuff where you need constant braking to get round corners then they might, but I've had disc brakes smelling of burning brake pad before they've started to fade.

    If they were rubbing hard enough to overheat then you'd barely be able to pedal.

    So my guess is a leak somewhere (the lever will be going spongy) or the discs and pads are contaminated (lever feels firm, but doesn't stop the wheel much).

    I assume the new pads have been properly bedded in?
    MTB/CX

    "As I said last time, it won't happen again."
  • nicklousenicklouse Posts: 50,675 Lives Here
    does the lever feel spongy? no then a bleed with do nothing.

    what did you ride through just before things changed?

    take the pads out and look at them.
    "Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
    Parktools :?:SheldonBrown
  • I've ridden in the Alps with XT discs. Never, ever had brake fade. Mind, I've only ever used Shimano pads.

    Sounds like the pads are not bedded in properly.

    2 choices. Ride a long road down hill with the brakes just on to create heat and then douse the pads and discs with clean water. Repeat until the pads bed in and work.

    Or. Reccommended by my LBS (I've never trusted it, at your own risk!!!!) Get a handful of the dirtiest mud you can find, smother the caliper and disc!!!! Ride hard and brake hard. You'll have NO brakes for 20 minutes. Then they will bite like a rabid dog!!!

    I'd go for the clean water method myself. Or buy Shimano pads, they work straight out of the box.
    It's not the winning or even taking part. It's the arsing about that counts.
  • Thanks for the comments, the other night I cable tied the brake levers back over night, kept the bike in the kitchen, when I had a look in the morning not a spec of fluid anywhere, so i went and bought some shimano pads and some brake cleaner, I gave the rotors and calipers a dam good clean, fitted the pads and now it stops dead with no squealing, the old pads must be contaminated or you get what you pay for, anyway it's sorted now cheers for the advice :D:D
  • thinking about it I ride through an industrial estate to work in the rain maybe split diesel caused the problem
  • bails87bails87 Posts: 12,998
    Possibly, just remember to be careful when lubing the bike. Keep WD40/GT85/grease/chain lube well away from the discs and pads.
    MTB/CX

    "As I said last time, it won't happen again."
  • will do this is the first bike I have had with disk brakes, I built it with discs as I was sick of listening to v brakes grinding away at my rims in the winter, would It be better to remove the pads when cleaning the bike and then use plenty of brake cleaner on the discs before refitting the pads :D
  • The RookieThe Rookie Posts: 27,757
    No just make sure you don't get anything 'oily' on the discs, also wipe anything off the discs (Kitchen roll works great) before moving the bike. Sintered pads also offer less stopping power anyway than organic, they last longer (especially in dirty conditions) but not really relevant to a commute!

    Simon
  • bails87bails87 Posts: 12,998
    As above, no.

    I've got discs on my MTB, I spray the bike with a hose, clean the frame with soapy water and a sponge, and then clean the components as necessary/appropriate with a stiff brush and soapy water/GT85/degreaser. Just use some common sense and make sure you don't spray degreaser or GT85 at the discs and you won't have a problem. E.g. if you're putting GT85 on the cassette, don't spray it in line with the rear axle because some will miss the cassette and go straight onto the discs, spray it downwards instead, or don't spray it at all! I give everything a quick rinse with clean water after a clean to make sure any accidental spills are at least diluted, if not removed and I've never had a problem.
    MTB/CX

    "As I said last time, it won't happen again."
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