[Norm Peterson]

Every once in a while, a few brake rotors slip through QC with 'cheeks' that are not of uniform thickness all the way around. Unequal heating = unequal expansion = disc thickness variation during operation = a shudder = most people go straight to "warped rotors" even though it's not that. Been there . . .

Rotors that have been overheated may have developed hard spots that can remain even after machining, and they won't wear as fast as the softer regions in subsequent use. So the shuddering returns.


Norm

[6sigma]

Originally Posted by Vtor_ZL1

Most likely uneven pad deposit. Re-bed them and see if problem goes away.


3 or 4 60-10mph stops, back to back, if it smokes, you are doing it right, if there's fire, you went too far. Keep windows down and smell for it.

I have pulse like a warped rotor at about 9k miles on my LT1 (has front SS Brembo brakes). After reading this thread I thought it might be uneven transfer, since the car has only been street driven and never really used the brakes hard. I tried the technique above - several 60-10 or 70-20 hard stops got the brakes hot, smelly and a little smoke. It seems to have helped! The pulsing is better but still there a little. I'll get them hot again and see if it helps more.

I was surprised the brakes started to fade quickly once they got hot. I installed a set of 1LE takeoff wheels and tires though and I'm guessing the extra grip might be more than the LT1 brakes are designed for.

[Norm Peterson]

Originally Posted by 6sigma

I was surprised the brakes started to fade quickly once they got hot.

That's what brake pads do, especially during initial bedding (where it's called 'green fade' at least in reference to track pad formulations).


Norm