My rear pad wore down to the metal..... the piston was a little tough, but i managed to screw it all the way in using some needle nose pliers.... how easy should the piston go in? The pad that touches the piston was the one worn to nothing..... is the caliper bad and needs replacing, or is that a normal wear pattern?

Thanks,

Matt

 

Basically the piston should rotate with some resistance from the seal,the resistance should be even throughout(ie from full extension to full retraction).The sliders should be cleaned and lubricated and should move freely.the parking brake actuator should also move freely(remove the spring to test).The pads should also fit easy in the caliper(it is usually necessary to clean all the rust off).If all the conditions are met and there is no evidence of fluid leakage the caliper is good to go,

 

It's a bit of a pain, you're shoving brake fluid back out of the piston.. If you open the bleeder, that helps, but you'll want to bleed the brakes after you're done.

No need to replace the caliper unless the piston is stuck and not retracting.