Len, I can tell you in the service station as a kid, we turned our own. More than once I turned rotors that were quite far from factory true.
I did too, heck I still take rotors in to have turned. I was on another forum and the concensus was that it's not the rotor that warps but brake pad dust & dirt that sticks to the rotor?Len, I can tell you in the service station as a kid, we turned our own. More than once I turned rotors that were quite far from factory true.
I think this is the key. Thickness variation, what I called unparallel surface when I was in the business, is usually what happens. I guess it is a form of warp ....This uneven deposition results in thickness variation (TV) or run-out due to hot spotting that occurred at elevated temperatures.
If we assume that what is said in this article is correct then I'm not sure that our "old" way of thinking was wrong, just the reasons behind it. In other words, when we perceived that the pumping was the result of warped rotors, we turned them. It really doesn't matter if it is the shape of the metal or the un-evenness of deposition that causes it, turning will cure it.