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  1. #1
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    XT brake vibration on 2013 Stumpy Expert Evo 29

    Anyone had/having a similiar problem with their m785 brakes on 2013 stumpy evo? I've put new resin pads on, new ice tech rotors, had brakes bled, bed the pads in correctly, the whole 9 yards. Rear brake is still vibrating clear through the frame under moderate braking, and getting occasional howl out of them as well. The switch to Ice Tech rotors definitely helped the howl, but did not solve the problem completely or eliminate the vibration. Wondering if it could have something to do with flex in the frame or other variables? help!

  2. #2
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    Someone else could shed more light than i but I do remember reading some threads on here about folks that were having a similar problem and they ended up getting a replacement rear triangle because of some sort of issue with the brakes resonating through the frame. You might want to hit up Spesh...

  3. #3
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    What kind of adapter did you use to mount the XT caliper, did you get rid of the Avid washers and use a Shimano adapter?

  4. #4
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    Yes it came with XO Trail WC. Not a fan of Avids and had already bought a set of m785's on sale in december before i bought the bike. Used the correct shimano brand adapters on it. Originally ran the stock 180 front/160 rear, so i believe it only needed an adapter in the front. Direct mount on the rear with a 160 rotor. The vibration was there in the rear with the XO brakes too, which is the main reason i switched the brakes out so quickly in the first place. I'm now running brand new 203/180 ice tech rotors with brand new resin pads front and back and new adapters for the different sized rotors. I don't think i'm missing anything?

  5. #5
    Elitest thrill junkie
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    Try adding some weight to the caliper. You have to change the natural frequency of it, that's the root of the problem. It's not necessarily easy to solve, as you've seen by trying "everything", but it goes to the natural frequency. My car has big weights added to the brake pads for the exact same reason. If you have the ice-tech pads, try running the normal ones, and if you have normal, try the opposite. There is some hope in that, but it also might require changing the caliper weight. Hobby shops and hardware stores sell little stick-on weights for pinewood cars. This can help.
    "It's only when you stand over it, you know, when you physically stand over the bike, that then you say 'hey, I don't have much stand over height', you know"-T. Ellsworth

    You're turning black metallic.

  6. #6
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    Just an update: 2013 Stumpy Expert Evo Carbon 29 with XT M785 brakes. Tried everything including new ice tech rotors, pads, sanding, bleed, etc. Ice techs helped considerably, especially with the squeal but the vibration was still there. What appears to have fixed the problem for me is removing the small brake hose clamp on the inside of the left hand chain stay that holds the hose to it. This makes sense in my head, as that is the only other point of attachment other than the brake caliper. I can prove the cause and effect relationship by removing it and putting it back on, so for any of you who were as desperate as I was, its worth a shot.

  7. #7
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    I had this same problem. One sure fire fix was to wrap the left seat stay with about three layers of an old tube. Looks a lot like what we used to do to protect the chain stay.
    The extra weight changed the characteristics of the rear triangle and the vibration/noise disappeared.
    Mike

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