| deans@wdeans.com 2005-07-24, 9:11 pm |
| Greetings,
> Did you ever hear of 'brake fade'. It's caused by excessive heat on the
> pads. When the pads heat up they will not stop the car normally.
Yes, I have heard of 'brake fade'.
It is not just caused by excessive heat lowing the pad's coefficient of
friction. In fact, brake fade is most often caused by boiling brake
fluid. This is often because the brake fluid has absorbed water
lowering its boiling point. Brake fade could be caused by
carbon-dioxide coming out of solution within the brake fluid at high
temperatures. Brake fade could be caused by outgassing of brand new
brake pads (even expensive ones). Brake fade could be caused by the
expansion of hot rubber brake hoses. There are probably many more.
Interestingly brake pads which perform better at higher temperatures
perform worse at lower temperatures and cause markedly more rotor wear.
This is why race car drivers need to "warm up" their brakes. Also
interestingly the type of pads used don't have much effect on how much
heat is generated. It generates the same amount of heat to slow a car
from 65 to 0 no matter what pad is used. Most interestingly and most
pertinent is that the $9.99 Semi-Metallic brake pads I purchased don't
build up enough heat going from 65 to 0 to cause brake fade due to
reduced coefficient of friction between the pad and the rotor. The
coefficient of friction is still high enough to lock the wheels if I so
chose throughout the entire deceleration.
If I sped up to 65 mph and then slammed on my brakes until I went to 0
and repeated the process several times I could cause brake fade. I
don't have to worry about that because I would never do it. If with
Kevlar-Carbon brakes I could repeat the process an additional two times
before brake fade set in it's not worth a dollar extra to me.
Hope this helps,
William
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