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Old 01-11-09, 01:56 PM   #1
big john
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Shreiking XTR disc brakes

A friend just got a new Blur LT with XTR discs and the brakes are quite loud. It's been back to the shop twice and they put new pads on it once. Are there Kool Stops or something to help this?
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Old 01-11-09, 02:08 PM   #2
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There's a process of seating the pads in, and if he isn't doing this it might cause it to make that noise.
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Old 01-11-09, 03:21 PM   #3
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Yup, sounds like your brakes haven't been bedded in.
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Old 01-11-09, 03:42 PM   #4
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I don't know about that process. I do know the last time he took it to the shop they were quiet until the first long downhill then they got loud again. I have Avids and they were always quiet.
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Old 01-11-09, 07:15 PM   #5
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wait till there is some pad residue on the rotors
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Old 01-11-09, 07:51 PM   #6
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My first answer to squeeking pads is always "face the tabs." This is especially relevant for the XTR rear.
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Old 01-11-09, 08:25 PM   #7
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How do unfaced tabs contribute to squeeking pads? Contact area? Vibration? I'm just curious.
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Old 01-11-09, 08:43 PM   #8
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How do unfaced tabs contribute to squeeking pads? Contact area? Vibration? I'm just curious.
Pads squeek due to vibration which is often due to misalignment. Plus fastening a metal/metal interface is always better than paint/metal.
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Old 01-11-09, 10:46 PM   #9
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Pads squeek due to vibration which is often due to misalignment. Plus fastening a metal/metal interface is always better than paint/metal.
I'll tell him we should try that. Has anyone tried any of the sticky anti-squeak products used on automotive brake pads? They keep the pad from vibrating.
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Old 01-11-09, 11:14 PM   #10
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Bad idea. While a car disc brake and a mtb disc brake run on the same theory, they aren't exactly the same. No fluids or sprays on the rotors.

If the facing the tabs don't help, I've had alot of luck with this:

Before doing so, check and see if the rotors are out of true/warped.

Loosen the mounting bolts, take 2 business cards, tear them in half, wedge in between each side of the rotor and spin the wheel and squeeze the brake lever.
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Old 01-12-09, 08:04 AM   #11
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Bad idea. While a car disc brake and a mtb disc brake run on the same theory, they aren't exactly the same. No fluids or sprays on the rotors.

The products I was referring to go on the back of the pad to make it sticky where it contacts the caliper.

If the facing the tabs don't help, I've had alot of luck with this:

When you say to face the tabs, you're talking about the surface that contacts the caliper, yes? Can you do it with a file or is a mill involved?

Before doing so, check and see if the rotors are out of true/warped.

Loosen the mounting bolts, take 2 business cards, tear them in half, wedge in between each side of the rotor and spin the wheel and squeeze the brake lever.
The last thing is to center the caliper?
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Old 01-12-09, 10:27 AM   #12
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Tighten down before removing the peices of business cards.
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Old 01-12-09, 10:47 AM   #13
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I'll tell him we should try that. Has anyone tried any of the sticky anti-squeak products used on automotive brake pads? They keep the pad from vibrating.
I have seen new replacement pads (cant specifically recall manufacturer or brake though) with a dab of what appears to be similar stuff on the back. If all else fails it may be worth a try, but with the close tolerances and relative finickiness of mtb brakes I would use it _very_ sparingly and with caution. I'd probably try a dab of high temp silicone RTV first, and then only on the contact points on the back of the pad, and allow to cure overnight.

I've been using non-chlorinated automotive brake cleaner on calipers and rotors for a while with no adverse effects (other than environmental of course).
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Old 01-12-09, 08:22 PM   #14
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Thanks, you guys.
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Old 01-14-09, 05:00 PM   #15
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I know this is a few days old, but here's some good info.

Use auto brake parts cleaner on the rotors.
Anti-squeal compound should be applied to the back of the pads.
Metalic pad compounds are more likely to squeal, but have great braking power.
Orgaic pad compounds are less likely to squeal, and aren't as grabby.
Overheating a brake can make it squeal, so don't ride the rear brake the whole way down a long descent.
HTH
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Old 01-14-09, 07:50 PM   #16
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If they work with noise I would be happy. When they do not work it hurts.
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Old 01-14-09, 09:23 PM   #17
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I know this is a few days old, but here's some good info.

Use auto brake parts cleaner on the rotors.
Anti-squeal compound should be applied to the back of the pads.
Metalic pad compounds are more likely to squeal, but have great braking power.
Orgaic pad compounds are less likely to squeal, and aren't as grabby.
Overheating a brake can make it squeal, so don't ride the rear brake the whole way down a long descent.
HTH
I'm over 200 pounds and kind of a wuss, so I use a lot of brake on long descent I do and those Avids never make a sound. Maybe they were set up right, but I would think the XTR could be quiet. I'm trying to get him to get the tabs faced/aligned.
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Old 01-19-09, 01:43 PM   #18
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First thing to try is simply clean the rotors with alcohol. If mine get dusty they tend to squeal a bit.
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Old 01-19-09, 03:38 PM   #19
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^ +1

Although what I use is "White Spirits." I wipe both sides of the rotors and both pads. Avoid touching the rotor with your fingers.

I had a "squealer" once and after the wipe down, it would go quiet for a while after the wipe, then start again after a day or so. I just kept wiping it whenever it got bad.

But what cured it once and for all wasn't my doing. After a muddy ride and a "water crossing," the squeal was gone... to this day!



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Last edited by Pocko; 01-19-09 at 03:55 PM.
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