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Old 03-27-13, 09:42 PM   #1
VNA
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Burning and screaming disc brakes

I am wondering if disc brakes will shatter or disintegrate in some fashion when they are so incredibly hot--would not be surprised if they glow in the dark!!!

Yes I have a good 3 miles of extremely steep climb and then I have to come down, the heat is one thing but the noise is another and vibrate the bike--kind of scary!

Anyone experience this phenomenon?
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Old 03-27-13, 10:04 PM   #2
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I don't know if rotors can squeal because they are too hot, but they occasionally can if they're cold. Squealing is caused by oils on the rotors or on the pads and it causes very quick slipping which comes out it the form of a squeal. Your pads may also be worn as well. Check them and if they're fine, then do a quick cleaning with rubbing alcohol or brake parts cleaner from AutoZone or something.

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Old 03-28-13, 02:51 AM   #3
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I'm running Shimano Deore hydraulic brakes with Hope floating rotors, the rear doesn't make noise, it just vibrates the *whole* bike under braking. So much so I'm considering selling it as a feature; women specific.
Actual performance isn't lost, from my experience. But I would soak the rotors in de-greaser for a while and then expose them to an open flame. If the cause is oils etc. you'll see it burn off in spectacular fashion.
I've had this problem far too many times, probably due to the fact my other half soaks her bike in lubes etc. every ride, probably not being careful enough and getting it on my bike too.
I would flame the discs and pads, consider buying new pads if performance isn't any better, then be careful with oils afterwards. I've encountered brakes becoming red hot, literally, and after I gave them a while to cool, they were fine.
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Old 03-28-13, 09:50 AM   #4
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I've had brakes "fade" when they get hot. Never have had a glow (that I could see) or a shake. Sometimes they will squeal at the weirdest times. Good luck on getting your brakes figured out. Sounds like you have quality stuff.
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Old 03-28-13, 02:26 PM   #5
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An out of round disk will cause tremendous heat.

On a long brake pull the pads get hot and release a gas that can cause the pad to 'bounce' off the disk.

One pad may be too close to the disk,

Something bent and the trailing edge of the pad hits the disk first,

Loose spokes,

Axle bearing/race wear that shows when the brakes bite down hard...

Get new pads and disks,,,


there, my useless 2 cents worth of Bhullhockey..

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Old 03-28-13, 07:49 PM   #6
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Loose spokes,
How would spoke tension have any effect whatsoever on disc brake performance?
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Old 03-29-13, 09:00 AM   #7
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How would spoke tension have any effect whatsoever on disc brake performance?
Yeah you caught that....

I guess my point was when you have a problem with anything that rolls, spins etc. Everything should be checked.
It's good to know people in here are looking out for the details wrong or right, they often make all the difference.


I've improved hi-speed braking performance on motorcycles by re-balancing the wheels. I have seen front brake efficiency gains by finding
the rear end tracking off a tiny bit.

A slightly out of true wheel set could very well increase brake fade/heat I would think..

Loose spokes often Indicate this right ??

Last edited by osco53; 03-29-13 at 09:05 AM.
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Old 03-29-13, 10:40 AM   #8
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I've improved hi-speed braking performance on motorcycles by re-balancing the wheels. I have seen front brake efficiency gains by finding
the rear end tracking off a tiny bit.

A slightly out of true wheel set could very well increase brake fade/heat I would think..

Loose spokes often Indicate this right ??
Balancing/truing wheels to improve handling under braking is not the same as increasing braking performance - the pads still clamp the rotor the same regardless of whether or not spokes or rim are even mounted.
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Old 04-06-13, 06:50 PM   #9
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http://www.pinkbike.com/news/Tech-Tu...rake-2011.html
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Old 04-07-13, 02:25 AM   #10
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Good info, good link.
There is graphite in the friction material matrix. So, if the above link does not help much, use a #2 pencil to make lines on the offending rotor... the squeal will stop for awhile.
Rear calipers mounted on the seat stay are prolly more prone to vibrate than those mounted inside the rear triangle.
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