2003 Buick rear rotors

Gm builds the parking brake into the rear calipers which makes every aspect of brake service complicated. You'll need a special tool to screw the pistons in. Many auto parts stores will borrow or rent that tool.

The rotors should just slide off once the calipers are removed.

Operate the parking brake repeatedly to pump the pistons out until the pads contact the rotors. The pistons won't come out by pumping the regular brake pedal.

Sorry to take so long to reply. The site stopped working on my regular computer.

Front calipers adjust automatically each time you apply the brakes, but rear GM calipers use a different type of piston. They have a mechanical actuator that is part of the parking brake. Using the parking brake periodically keeps them adjusted up but that has nothing to do with binding or sticking. Many people are afraid to use the parking brake because on older cars the cables can stick and not release properly. That is REAL common on Fords but it can happen to any older car, especially if you live in Wisconsin where they throw a ton of road salt on an ounce of snow.

If you think your cables might stick, understand that rear brakes only do about 20 - 30 percent of the stopping so they wear down much slower than the front brakes. That means it will take a very long time for the pedal to go low. When mechanics replace the front brakes, they will adjust the rear ones too. That can be done by using a pliers to operate the levers in the rear calipers so they don't risk applying the parking brake and having the cables stick. A few strokes on each lever is all it takes to be sure each piston is fully adjusted.