I have a question on rear brake caliper pistons. I just did all 4 brakes on my Elantra, with new rotors, pads, lubed the sliders, etc. On the rears, the piston has one of those type that needs a tool to turn it in a clockwise direction to retract the piston. I did this, with the tool, everything went great. I did the rears first, and when they were done, I pumped the brakes back up until they got firm. Then went on to the fronts. After completion, I took the ca out for the 60 to 30 braking bedding-in, and came back. The fronts looked great, nice grey finish appearing on the rotors. The rears, don't even look like they were ever working at all. Now, since those pistons have to be turned to retract, to they expand to take up clearance in the same way? Shouldn't there have been some kind of wear marks on the rotor? They held the wheel just fine when brakes applied and trying to turn the wheel while up on jacks, so I know they are clamping and unclamping as advertised. Whats the story with this?