From a brake engineer I spoke with - FYI

You are right. Rotors do warp. Pad material transfer can make a pedal pulse, but cleaning the rotor will restore the system. Cleaning a warped rotor will not restore the system to normal.

Cast iron is basically a composite of iron and graphite. Residuals stresses caused by casting or machining problems can cause the rotor to warp as these stresses are relieved by vibration, heat cycling, wear, etc. Uneven heating/cooling can also warp the rotor.

You can determing if a rotor is warped if you put a dial indicator on it and rotate the rotor on the spindle. I do this when I install rotors on my own vehicles so that I know that the rotor is running true. I've found some rotors are warped when you get them

 

Thanks for the interesting post. Seems kinda random. I think that my rotors may be warped, but I have not had them tested. I have a funky vibration at slow speeds in the front end. I guess that I should have this fixed. I assumed it was out of alignment as I put on new springs and after the install it has not been right. Anyway, thanks for the info!

 

Not familiar with the other thread, but are there people who don't think rotors can warp? Thought that was basic knowledge for car people.

 

There are a number of conditions that can lead to a pulsing pedal. As novice car guys, we tend to gain knowledge in areas of experience, good or bad. I've never experienced pad material transfer, which can happen for a number of reasons. I have, however, experienced true warping, a condition that was dismissed by a few others in the other thread.

Sometimes, we assume the experience of others is not credible becasue it has not been personally experienced or we've not read about it anywhere. This thread should help to round out some of the potential problems with rotors. The engineer I spoke with is working on some other questions for track realted duty. I'll post findings here.


The other thread is under suspension and the title regards dust shieds. Read the entire thread; there is one usefull link, some sarcasm, and, some genuine information.

One point brought up by the engineer, treat rotors like halogen bulbs; do not get any body oil or any other oil on these. Our bodies contain acids as well and this can be found in body oil. "Clean all rotors extremely well before operation."

 

http://www.stoptech.com/tech_info/wp...rakedisk.shtml

 

That was the valuable link I wrote about above - originally provided by Vader. However, warping rotors is not a myth.

 

Amen, brother!