I have 95 Caprice that I have put 4 sets of brakes on in 80,ooo miles. The first set was warped when I got it back from shop. I did rear at same time. I had them all turned, but they warped again almost immediately. I put on another set of rotors with new calipers. It took 2 weeks to warp. Next time I used Baer decelas on it with new pads and brake lines up front. These rotors are drilled and slotted, and guaranteed not to warp for 3 years. It took a month. I put another set of Baers and new pads on. I carefully torqued wheels to spec. They still warped. Sometimes they don’t feel too bad, and then 5 minutes later they shake the car when I stop. No matter how gently I drive, it still happens. I haven’t tried a new master cylinder or proportioning valve yet. Any suggestions?
Its not really warpage it is thickness variation. GM put out a very detailed TSB how they wanted their mechanics to test for thickness variation.
The first thing that comes to mind is we are not dealing with a thickness variation you need to follow GM’s procedure for measuring thickness variation and see if the specs indicate this is the problem. After so many rotors you must verify your conclusion about “warping” or move on to other possibilites.