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  1. #1
    Yes, that's fonetic
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    Need help with a HOWL

    I've searched the threads and couldn't find this exact problem. I have '03 xtr disc/xtr tubeless rims and the front brake was making a gawdawful squeal under heavy braking. Took it off this am to check and clean the rotor and when I hold the rotor in the center and flick the disc there's a definite rattle. Took off the back, tried the same but got a solid ping (no rattle). I can't find a crack anywhere....could one or more of the rivets be loose? Guess I gotta deal with Shimano for warranty as I got the bike from Wrench Science. Don't get me wrong, they've helped me b4 on another warranty issue, but it just takes soooo long to get anything done when the 'middleman' is involved.
    Any ideas short of sending it back to Shimano?

  2. #2
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    Quote Originally Posted by whodaphuck
    I've searched the threads and couldn't find this exact problem. I have '03 xtr disc/xtr tubeless rims and the front brake was making a gawdawful squeal under heavy braking. Took it off this am to check and clean the rotor and when I hold the rotor in the center and flick the disc there's a definite rattle. Took off the back, tried the same but got a solid ping (no rattle). I can't find a crack anywhere....could one or more of the rivets be loose? Guess I gotta deal with Shimano for warranty as I got the bike from Wrench Science. Don't get me wrong, they've helped me b4 on another warranty issue, but it just takes soooo long to get anything done when the 'middleman' is involved.
    Any ideas short of sending it back to Shimano?
    Were the fork tabs faced? Even a slightly out of (planar) alignment caliper causes the pads not to sit squarely against the piston (when in use) which can cause squealing. The rivets being loose are likely a result of the vibration not the cause. Once the brake is under load the ring should tighten against the center. (all 2 piece rotors eventually loosen) (just like pads, loose till they are under load)

  3. #3
    Yes, that's fonetic
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    I really don't know if the tabs were faced

    Quote Originally Posted by Grumpy
    Were the fork tabs faced? Even a slightly out of (planar) alignment caliper causes the pads not to sit squarely against the piston (when in use) which can cause squealing. The rivets being loose are likely a result of the vibration not the cause. Once the brake is under load the ring should tighten against the center. (all 2 piece rotors eventually loosen) (just like pads, loose till they are under load)
    is that a normal proceedure for a new fork? I'll have to contact Wrench Science to see if that's part of their setup/build proceedure (I doubt it ) I also doubt there's anyone here on Maui that could do that for me

  4. #4
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    Quote Originally Posted by whodaphuck
    is that a normal proceedure for a new fork? I'll have to contact Wrench Science to see if that's part of their setup/build proceedure (I doubt it ) I also doubt there's anyone here on Maui that could do that for me
    Yes facing should be always performed before any iso direct mount brake (like the XTR) is installed. However, sometimes it is not done carefully, and sometimes it is not done at all. At any rate, check with the builder to see if the fork was faced.
    You can verify if a fork has been faced as the tabs (wheelside) where the brake bolts on there will be clear aluminum circle (paint removed) and a pattern of circular machining marks should be evident. (though seeing this would normally require removing the brake caliper from the fork.) Evidence of a previous facing is unfortunately no guarantee that it was done well however.

    You can try swapping the rotors to verify my diagnosis, my guess it that the front one will become noisy again after the pads bed to the new (swapped) rotors.

  5. #5
    I already rode that
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    I took the paint off my tabs where it wouldve been and only a few times did my XTR squeal. Unless of course its wet or something but a few hard brakes and its gone.

  6. #6
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    Quote Originally Posted by SuperNewb
    I took the paint off my tabs where it wouldve been and only a few times did my XTR squeal. Unless of course its wet or something but a few hard brakes and its gone.
    Bare mounts are likely better than painted, however that is not equivalent to facing. Facing ensures that the mount surface(s) are parallel to the plane of the wheel (and disc). Some facing tools even ensure that the mounts are even (coplanar). This is not to say that an unfaced mount can't be parallel (it might be in the ballpark but it is unlikely that it would be as parallel as a faced mount)
    On ISO mounts, direct mount brakes (ISO) are lighter and perform better (a more secure mount), but are a PITA to set up (facing and shimming) If you skimp on the set up the brakes can perform poorly, take forever to bed pads in and howl like a banshee. (btw, normally the better a caliper is aligned the sooner it quiets after getting wet)

  7. #7
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    Thanks for the info

    Quote Originally Posted by Grumpy
    Bare mounts are likely better than painted, however that is not equivalent to facing. Facing ensures that the mount surface(s) are parallel to the plane of the wheel (and disc). Some facing tools even ensure that the mounts are even (coplanar). This is not to say that an unfaced mount can't be parallel (it might be in the ballpark but it is unlikely that it would be as parallel as a faced mount)
    On ISO mounts, direct mount brakes (ISO) are lighter and perform better (a more secure mount), but are a PITA to set up (facing and shimming) If you skimp on the set up the brakes can perform poorly, take forever to bed pads in and howl like a banshee. (btw, normally the better a caliper is aligned the sooner it quiets after getting wet)
    looks like I'll have to spring for a Hope Spot facing tool. O well, I'm already better tooled up than most of the local shops anyway

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