I'm replacing my rear brake pads for the first time. The old ones are worn down almost to the metal, so the space between the caliper and the piston is too small to fit the new ones. I've tried gently pushing to open the space and nothing. What should I do-force them open? Thanks for helping out a newbie!

Quote from: vmichelI'm replacing my rear brake pads for the first time. The old ones are worn down almost to the metal, so the space between the caliper and the piston is too small to fit the new ones. I've tried gently pushing to open the space and nothing. What should I do-force them open? Thanks for helping out a newbie!

When I was replacing my rear brakes, the calipers were pretty easy to push back just with ... So you better check your calipers.

 D.

Open up the resivoir, that'll allow the brake fluid to flow back up the line into the resivoir. Just be careful that it doesn't overflow when you're pushing back the old pads.

Use an old pad to pry the caliper piston back in. It does take some force. There is dirt that builds up around the piston, so it needs to break loose. You can loosen the bleeder screw and let the fluid come out (put a hose on it first)
if it still won't budge.
Tighten the bleeder screw after the piston is moved back. It won't allow air to get in this way.

I would highly recommend removing that dirt before pushing the piston back in. Check your can of brake cleaner for compatibility with rubber before doing so, but 1-2 quick blasts of the stuff will generally get the piston in pretty good shape. Any dirt or grime that is on the piston is really hard on the caliper seal and can lead to its failure. It can also contaminate the brake fluid.

I actually just did this a couple days ago. What I did was totally drain the brake fluid.. im thinking it was really old. Then I disconnected all the lines and took the pads out. Then I was able to unbolt the caliper and slightly tap the pistons back into place using a hammer. Keep in mind I didnt want to do this but nothing else would work (channel locks, pliers, finger force, etc). It didnt harm anything at all and they work great now. Hope that helps.

Mick