Can't retract rear brake piston

[cheelees]

Hey guys,

I set out trying to replace my rear brake pads for the first time today, and all went well until it was time to put the new ones in. I did the stupid thing of trying to see what it looked like when I pressed my rear brake, so now the pistons are quite far in and they don't budge when I push them back in.

What do I do? It will be quite hard to take the whole caliper off because my exhaust doesn't allow me to properly access the nuts.

Here's a picture of what it looks like: http://imgur.com/HncZL1i

[fetor56]

You should be able to push the pistons back unless one or two have exceeded their maximum travel and at least one piston(the outer one most likely) has gone past the pressure seal.Maybe try lubricating that piston with fluid to get it back past the pressure seal,but i don't fancy your chances.........BE CAREFUL.
You'll need to bleed the brakes IF successful but that's an easier job with the rear.
Personally i suspect you'll need to remove the caliper cos it also helps to rotate the lubricated piston as u push down from both sides,to get them past the dust and pressure seals.

Tip for a removed caliper,no hydraulics: A good air foot pump is great for extending the pistons to see if their working correctly,have some wood between the pistons so they don't exceed maximum travel.....let us know how it goes.

[Jimbob]

Also it does take a decent amount of pressure to push them back in.

[cheelees]

I've tried pushing them back with various tools but nothing's working, will try open up the bleed valve and try again

[lucas]

You can try opening the bleed nipple. I'm not sure if that'll help or simply make a mess.

Sounds like it might be a great opportunity for putting in a brake rebuild kit.

The pistons are made to slide all the way out and back in (for service) so I'm not sure what is happening to you.  Perhaps they are going in crooked?  Maybe you aren't pressing hard enough?   I use c clamps on mine, takes no effort.  Wear safety goggles though in case something is binding and it snaps off and embeds in your eye ball.

[DaMuffinMan]

Did you remove the fluid reservoir cover before trying to push em back in?