Caliper piston... worried

[MattAvino]

Im in the midst of rebuilding all my calipers, i just finished the first one, its the rear right. After fully cleaning in up and i put the new seal in, i was able to easily push the piston back in with my thumbs, should there be more resistance? Is the original piston shot? Is the caliper cylinder shot?
If this is bad what should I do?

[jlevie]

With no fluid in the caliper the piston will move pretty easily.

[mr2peak]

Did you remember to replace the O ring? I'm sure you did, but just checking

[MattAvino]

yes, I replaced it? what would a new piston cost, and where?

[KVF]

No way your piston shrunk in diameter, unless you took to some serious sanding of it. If the inner surface is corroded, pitted, or warped would be the only time to replace it... I test to make sure mine hold pressure with a block of wood and an air compressor.

If you need new ones I'm certain bimmerworld (about 25 buck per piston iirc) carries them, but check with Blunt first to see if he does. Good luck.