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Old 01-10-2008, 11:51 AM   #6 (permalink)
wgondor
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Car: 2005 Chrysler 300C
Join Date: Nov 2007
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Quote:
Originally Posted by DZeckhausen View Post
The pads had glaze for a couple of reasons. See my comments below

What you've done here is to combine the bedding for street pads with bedding for full race pads. It's not a case of if some is good, then more must be better. By doing the bedding at 80mph, then adding four runs at 100mph, you completely cooked those street pads. A layer of glaze formed on them and, since you don't have slotted rotors, it remained - causing the squeal at light pedal pressure and should have reduced your friction level somewhat.

Keep in mind that the energy you put into your brakes goes up with the square of the velocity. So an 80mph stop is not a 33% increase in energy over a 60mph stop. It's a 75% increase. And a 100mph stop is not a 66% increase, it is a 178% increase. (If I did the math right.)

In this case, it was a pad issue.

After they deglazed the pads and turned the rotors, it became a pad & rotor issue. You've essentially gone back to square one. There is no pad transfer layer on the rotors, after they've been machined. So you need to rebed the brakes, this time only doing a series of near stops from 60mph (per: http://www.zeckhausen.com/bedding_in_brakes.htm). If the pads haven't been ruined from the abuse earlier, this should cure the noise. If it does not, then you should replace the pads.
Thanks for this info. I have been having a similar issue with the rear right on my 300C only when cold overnight. This has seemed to resolve this (where Chrysler service people say "this is normal, etc")
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