I've read about this problem and I seem to behaving it with my AAR. My AAR has the 11" rear drums with front disc brakes. On hard braking, it has a tendency to lock up the rears pretty easily. The back end wants to come around on me when this happens. I've heard that you can put the smaller 15/16 wheel cly on the rear and eliminate this problem. I've yet to try this. I need to check out all the brakes on this car first. With that in mind, I'm working on a 70 RR for a customer. It's a manual drum brake car with 11" in the rear. If she goes with power disc up front, will I have the same trouble with the b body if I leave the 11" on the rear or should I change to the 10" to avoid the problem. Would the 15/16 wheel cly solve the problem easily? Anyone that has firsthand experience have any thoughts?