rear brake caliper piston stuck

[Monyx]

frigged if I can move them back to make room for the new pads, searched and read the tips on removing reservoir cap, draining some fluid, leveraging a gap between the old pads by opening up long nose pliers of inserting then then twisting flathead screw driver. so are the old pistons, scored and stuck in there and caliper in need of rebuild? pads were evenly worn down and rear brakes work(ed) fine without undue pressure. just can't move the pistons back

[Shifu]

If they worked fine then it is unlikely that they are stuck all of the sudden. It is possible that, if the pads are used all the way to the backing plates and your disc is a bit thin, they could jam because they almost all the way out of caliper. Especially if you have used the implements like you described to push them back. It is likely they are on the piss and will not badge untill you get them straight again. Hopefully you have not damaged the caliper trying to push them back too hard. I would suggest you install the old pads and assemble them back on the disc. Then operate the brake pedal. That should straighten them out again. You best chance to push them back evenly - just loosen the bleeder and push the whole caliper against the disk one side then the other. It can slide sideways so there should be no problem. Failing that - complete service job.
Good luck...

[Greeny_SA]

frigged if I can move them back to make room for the new pads, searched and read the tips on removing reservoir cap, draining some fluid, leveraging a gap between the old pads by opening up long nose pliers of inserting then then twisting flathead screw driver. so are the old pistons, scored and stuck in there and caliper in need of rebuild? pads were evenly worn down and rear brakes work(ed) fine without undue pressure. just can't move the pistons back

I took mine to the local power brake bloke's & they threw a kit through the caliper $90 I think .

[cyndemgum]

Refill the master cylinder. Whilst the caliper is off pump the brake until it pops the piston out of the caliper. Completely drain the caliper and master cylinder. Clean out the caliper, you will be surprised at the debri that has collected. Check to see the piston and caliper has not been marked. Lightly coat the piston with rubber grease and reassemble. Up to you as to replacing the rubbers as that will depend on their condition. Refill with dot 4 and bleed. Paul.

[Monyx]

update - you live and learn...nothing wrong with calipers, and the tips on undoing cap and draining fluid or leveraging the old pads to push back pistons were not useful for me. I simply hadn't had experience and learnt doing it this way: remove caliper from mounts (but leave line attached) and use fingers palm to alternately push the pistons back, being dual piston opposed one will pop back inwards if you push the other too far back. get them even and as far back as I can (quite easy) and simply install pads. done in 5mins once I found out the right way!