patrickt OFF THE MEDS AGAIN!@#$$%%$#$#@# Rear disc Brakes and calipers, GM has 3 kind, 2 with internal adjusting parking park units and 1 with seperate mechanical in the hat of the rear rotor.
The first 2 calipers need to have the cups rotated all the way in to reset them WITHOUT breaking the park accuator inside the cup. Using a "C" clamp will break it every time.
The 3rd one works like a front caliper with just compressing it with a spreader or "C" clamp. I use a spreader because if this doesn't do the job there is something wrong with the caliper or brake system. You should not need 300 pound of force to retrack the cup.
To set parking brake after repair. Pump the pedal until you feel a good one, then apply the parking brake 3-4 times and release should go about 1/2 way down and hold.
Side note some of the older calipers on late 70's cars through the 80's you have to adjust the parking brake first to set the pad clearance, then pump the brake pedal. After this was a pressure bleed of the system. Early ABS systems where a bit!@#$$ch to get working. Last thing do about 5-10 heat cycles, stop and let brakes cool off to breakin the pads and rotors. If not they can glaze and you get poor braking.
That's it Pat, can I go now????
. Get back on your meds and stop HUFFING 134A and 22.
Rick