warped rotor - front or rear

[The Critic]

Originally Posted By: Donald
So if the rotors when people saw warped are not really warped but rather no longer of uniform thickness, how does this happen? Is the iron softer in some areas? I don't see how pads would wear it so its no longer of uniform thickness. If a rotor was truly warped I could see that might have happened from overheating.

It could occur due to an aggressive brake pad compound that was wearing the rotors unevenly. This was a common problem with GM and was outlined in the article "BIG 3 BRAKE SYMPOSIUM 2001".

Rotor runout can also cause uneven rotor wear. If there is excessive runout, it can cause the brake pad to wear high and low spots onto the rotor. This will cause disc thickness variation, which results in a pedal pulsation.

 

[The Critic]

Originally Posted By: Donald
So if one has the caliper'ssliding pins lubricated, and the rotors machined should this happen again, unless the sliding pins stick again?

If the rotors are resurfaced and the runout is also within spec, then it shouldn't happen again as long as the pad compound is not wearing the rotors unevenly.

Generally, I've personally found that it's best to address pedal pulsation complaints by replacing the pads AND rotors at the same time.

Also, always replace rotors in pairs, and always replace pads whenever the rotors are resurfaced or replaced.