Ok, so I've changed lots of disk break pads before with no issue. I have new pads and rotors for my car. The drivers side went together easy. I just can't seem to get the passenger side caliper to open up enough. It's super close but not quite. I have always just pressed the piston back in with a pair of channel locks. The pads are power stops if it matters. I don't have the box that the rotors came in.