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post #1 of 32 (permalink) Old 09-05-2008, 07:12 AM Thread Starter
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Brake chatter

I have this odd sort of situation that's been going on for quite a while and I'm not sure what to make of it. It was exasperated in my last track day.

When the bike is cold, the front brakes work spectacularly. After a while or on a hot day, when the bike slows to say 20mph and the front brakes are applied, the front brakes chatter, very much like the rotor is warped (continuous, pretty consistent skipping). This is not seen in the cool mornings even at low speed.

Since I just pulled the front wheel off for a tire change, I loosened and re-torqued all the rotor bolts to spec, hoping this would resolve the issue; I haven't had a chance to ride it since the change.

Anyone have any thoughts on what might be happening? Could the rotors be perfectly flat/straight until they heat up, and then warp? If so, I presume my only option is to replace them, but how do I avoid this situation in the future? What are some possible causes?

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post #2 of 32 (permalink) Old 09-24-2008, 11:42 AM Thread Starter
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Well, after some looking into it there are a few people who had suggested using a combination of a buffer (sand paper, really) and then a rag to wipe away remains. The posted theory was something about tiny particles collecting in rotor pores.

I've never had to do this on a car and didn't on my first bike. However, I gave it a shot and its markedly better. WTF? Anyone have any thoughts on what's really going on here?

Its not completely better and some have suggested pulling of the pads and running them over the buffer on a completely flat surface too, which I might try to see if it resolves the issue completely. when I have time.

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post #3 of 32 (permalink) Old 09-24-2008, 01:38 PM
 
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Are you certain you did not get any oily fluids on the pads?

Edit: If not, it sounds like you glazed them. After sanding the pads, take care to re seat them properly




Last edited by Vash; 09-24-2008 at 01:42 PM.
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post #4 of 32 (permalink) Old 09-24-2008, 01:49 PM
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Originally Posted by kanwisch View Post
Well, after some looking into it there are a few people who had suggested using a combination of a buffer (sand paper, really) and then a rag to wipe away remains. The posted theory was something about tiny particles collecting in rotor pores.

I've never had to do this on a car and didn't on my first bike. However, I gave it a shot and its markedly better. WTF? Anyone have any thoughts on what's really going on here?

Its not completely better and some have suggested pulling of the pads and running them over the buffer on a completely flat surface too, which I might try to see if it resolves the issue completely. when I have time.
Your pads got glazed. I am going to assume you have been playing on the track... It'll happen from time to time; no big deal.

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post #5 of 32 (permalink) Old 09-25-2008, 07:20 AM Thread Starter
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Thanks for the glazing comments. Its always had some chatter since I bought it used, so I'm wondering if the newb who owned it before me glazed them on the track. Surely I helped that along

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post #6 of 32 (permalink) Old 09-25-2008, 08:11 AM
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Thanks for the glazing comments. Its always had some chatter since I bought it used, so I'm wondering if the newb who owned it before me glazed them on the track. Surely I helped that along
Just keep an eye on it. If it does it again, pony up for the new pads and be done with it.

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post #7 of 32 (permalink) Old 09-25-2008, 08:16 AM Thread Starter
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I'm going to give the sand-paper a shot but putting out for new pads isn't a big deal. Got a nice travel reimb coming from the company for some travel on the bike.

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post #8 of 32 (permalink) Old 09-25-2008, 05:16 PM
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I have what sounds like a similar problem. Might try the sanding trick myself!




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post #9 of 32 (permalink) Old 11-03-2008, 05:07 AM Thread Starter
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I tried the sanding of both the pads and rotors and still have some high speed chatter, which isn't acceptable. Now the hard question is whether to change the pads (which have LOTS of material left on them) or the rotors. I'm leaning toward the rotors because the chatter varies each time I stop, though rotor changes usually are required when you have runout (shown as pulsing on the brake lever).

The reason I wonder about the rotors is that I change that front tire pretty often when going between track and street and think its possible it got a jarring somehow. However, I did the pencil test to see runout on the rotors and simply didn't see anything significant.

Rotors would be $115, pads look like they're $53 at the Toy Store. Anyone got a recommendation for place to start?

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Dragging knee is for the track, and dragging tail is for the lot. --Kane Friesen

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post #10 of 32 (permalink) Old 11-03-2008, 05:31 AM
 
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Before you go off spending money, why don't you measure the run out on the rotor?



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