XT Disc Brake Squeal....- Mtbr.com
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  1. #1
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    XT Disc Brake Squeal....

    They usually run very quiet. However I recently replaced the pads (M07-S) and now I have a squeal. They spin free in the stand no rub (one small-small spot). I can even ride for a 10minutes or so and they are good. 20 minutes into the ride the squeal starts. If you brake it goes away only to come back again.

    So I tried to get rid of it by recentering the pistons. Essentially I leveled the caliper, removed the pads, removed the lid on the caliper, pushed the pistons all the way back, then put the lid back on. Next with the pads in I used the orange spacer provided by shimano and pulled the brake. Next I put my wheel back in and everything seemed fine. But it came back in the next ride.

    Any suggestions? For reference the pads the type I previously had in. The rotor is not bent.

    The wheels are beat up pair of 355 29ers and the bike is a stump 29er ht.

    Thanks in advance.

  2. #2
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    model check

    Is it 775? Mine started squeal in cold weather and stopping power gone. Reason - leaking calipers -> oil on pads.

    There are many "cold weather leaking" reports on mtbr.com (mine is last one).

    I gonna swap calipers to old LX (fortunately I have spare ones).

  3. #3
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    Checked pads they are good. Road it today not nearly as bad after the last piston pushing. Seems like the outboard one sticks out more and is the culprit. Also no mineral found around the caliper area. Probably just need a good bleed, either that or I have a sticky dominant outboard piston. Any other suggestions?

    The cold does make them act weird though. The levers get hard as a rock to pull.

  4. #4
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    Cold causes lines shrinkage -> less levers stroke.
    There are lever adj-knobs on 775-s.

    P.S. anyway, keep pads-rotors CLEAN.

  5. #5
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    Good job! rotor / pad cleanliness`

    When I first read that a guy on MTBR bakes his pads in a toaster over to get rid of the squeal and loss of power, I thought hmmmm??? Well I first did it by holding them over an open flame on the gas grill. It worked decent, it defintely cooked off a little grime and oil. BUT Now about once a month, I clean the rotors with isopropyl and use some needle nose, and a MUCH Hotter plumber's propane blow torch, to cook off the mud and grime and sometimes mineral oil. Then just cool them in a bucket of water. It's like washing em with fire. Good as new. Then my brakes are insanely powerful so long as I have a good bleed. I think even with a little oil contaminated on the pads, the flame evicerates the oil. I can tell oil is buring off by the smoke. When there is no more smoke, they're clean. so before you trash those "contaminated" brake pad,give this fix a try

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