[Closed] retracting pistons

you can just use a tyre lever to push on the pads and force the pistons back into the calipers. It's likely to just pop out to it's previous position the first time you use the brake, though.

do they rub all the time or just at one point on the disk rotation? If it;s the latter a quick tweak of the disk will stop it.

Large flat blade screw driver between the pads and wiggle. Just be careful not to damage your pads, a plastic tyre lever will sometimes do the job. May need to do it a few times to unstick the sticky piston.

thanks guys.would it work better if i opened the resevoir cap on the lever to let the fluid settle once ive moved the pads back in??

I've had this before with SLX brakes.

I removed the pads - pumped the pistons out a touch and cleaned them.
Push them back in, clean and repeat 4/5 times.

I also replaced the spring and after this they then move back to give some clearance after braking and stop rubbing.
I found that if I don't do this regularly they end up getting the discs rather hot on long descents to the point the at the fluid heats up and causes the brakes to come on and make a hell of a noise

I think they may need proper stripping down and cleaning at some point.

I've got these brakes: Unbolt the caliper, skoosh in some lubricant (I used GT85 which is supposed to knacker the seals, but ok sofar),leave to soak.
Use the jaw of an open ended spanner round the caliper body and the piston that's NOT stuck; pump the brake lever a tiny amount (don't overdo it!) to get the stuck piston moving again.
Sometimes levers won't return because of gunk in the plungers, so lube in there as well!

here's a tip from a busy bike workshop 😉

remove the pads and spring, grab the brake lever and pump the pistons out a little (not so far as to have them pop out)

if you find one piston moves out and the other sits still, use a 10mm ring spanner to retain the moving piston, this will apply pressure to the static one and get it moving

once both pistons have some exposed depth, use a silicon grease or spray lube (Fork Juice is ideal) on the piston's diameter, and then push the pistons back into the caliper with the ring spanner, wipe any excess off the exposed face of the pistons

install the pads / spring and go ride..

this effectively lubricates the piston body and piston seal with silicon, which has enough heat resistance to not become mobile and leak onto the pads once the brake gets hot

you can get DOT specific silicon rebuild grease (Avid offer this) but general silcon grease (RS) or spray works just fine 😉

Agree with the last man but not chickenman!! GT85... 🙄 🙂

easiest fix without lubing the pistons etc is simply to use your hand ( maybe cover with kitchen towel to avoid contamination ) to push the disc over in the direction of the draggy pad (and therefore push it back in slightly) whilst at the same time pumping the lever to allow the other pad to move out a little more. then release and with a little luck no more drag . If not try again or go down the pad removal piston lube reset path.this is all subject to the disc being true in the first place.