Um, may sound like a stupid question, but I'll ask anyway because i don't want to mess anything up.

My rotors are grooved/warped. So i bought the cross-drilled & slotted rotors due to all of problems w/ the stock ones. I also bought new pads. I'm in the process of installing them. I installed all the rotors, no problem. I reassembled the front calipers (using a C-clamp to slowy push the piston in.) Now my Problem. I can't get the back caliper's piston to go in at all. I've never had this problem before on any car. Is there some sort of trick or whatnot to get the piston to back into the caliper so i can reassemble them? Figured I'd ask before i try forcing in it, don't want to break them.

 

on some cars they have to be screwed in but i havent changed the ones on the cobalt yet.