There is a set screw on the back of the Caliper that you turn to compress the piston. You use the same set screw to adjust the brakes when you change brake pads.
Caliper pistons should retract if calipers are in working order. Calipers need to be removed and rebuilt or replaced. A brake fluid flush is highly recommended.
The calipers should turn back in with a big scredriver or such! you have to rotate the piston to retract them rotae the pistons clockwise with a large pair of pliers
Depending on the make/model/year of vehicle, you may have to get a rear caliper tool. Some rear calipers need to be turned to retract them.
This is caused by the pressure release in the brake lines when you retract the pistons in the brake calipers to accommodate the new brake pads that are thicker than the ones that are removed.
the piston on the rear calipers will turn in a clockwise motion and that is how they retract.
The stupid people used ceramic pistons in the calipers and they have worn crooked so they are binding up the pad so it rubs on the rotor. The piston won't retract back like it should.
You will need the tool to retract the calipers. The piston in the rear calipers have to be turned clockwise as you compress them back in.
If you do not want to spend any money, then, put the old pads in and use a bar or screw driver to force the pistons back................BUT, in all good sense, just go to your local auto parts and buy a small tool that will do the job for you. It is not expensive, then put the old pads in and put the tool between them, and just turn the screw. It will force the pistons back with no damage. If in the event the pistons are very hard to retract, then I would suggest to replace the calipers. Good luck.
When there is to much resistance to retract the piston, When the rubber piston(s) boot/seal is damaged/torn, When the bleeder is broken/stripped,
Kia's have rear calipers with screw in pistons. You must buy a tool from your local auto parts store called a "cube" it has little notches that fit into grooves on the piston. Then attach a standard socket and screw in the piston.
You can either use a c clamp or c clamp vise grips hope this helpa
Try exerting pressure while turning clockwise to retract