Brakes problem
1996 Pontiac Sunfire 4 cyl Front Wheel Drive Automatic 120000 miles

As part of normal wear indicated, I changed front brake pads and rear shoes. I did not turn rotors or drums because they looked and felt good. Ten miles later the rear of the car began squatting and jumping when I hit the brakes. The local garage in town said that I had one set of shoes swapped wrong, front to back, they corrected this, but 10 miles later I was back again. I took it to a GM dealership and they determined that the drums were warpped, so they changed them and said that the shoes were in good shape. 10 miles later it was back again. When I hit the brakes, the car seems to squat and it seems like the car is jumping with each revolution of the wheel. It is definately coming from the rear of the car. I don't want to let any more mechanics guessing as they take my money.

I saw a bulletin that might pertain to your problem, bulletin # 73-50-18. It talks about the parking brake not releasing all the way. You can park the vehicle on level ground, block the wheels, tranny in park, see if you can roll the wheels by hand without too much effort. If you have a wheel trying to lock-up, it should be obvious. You can cycle the parking brake a few times, test the wheels again.

It might not be the parking brake, but, if a wheel is trying to lock-up, it shouldn't be too hard to spot.

I have the same problem in my car. when you barley touch the brakes the back end squates down. and some times you might hear a loud pop sound when you realse the brake. It would be the self adjesters not doing there job right. you can buy the kit at any auto store. most of the time it seems as if they wear out and that what causes the squating in the back end.