Brake caliper pistons

[Anonymous]

I've decided to rebuild my brake calipers, as the front brake seemes to drag. However, I can't get the piston out of the caliper body. It moves in and out about 1/2 inch but with great mechanical effort on my part. I see a brownish/red liquid material within the caliper body. The visible part of the piston looks great (except for the few small scratches I just put in it trying to get it out of the caliper body). I've even gone so far as to put channel-grips on the piston (with the caliper body screwed to my work bench) in an attempt to torque and pull the piston out.

Any thoughts?

[Anonymous]

No, not pliers!

Put the brake pads in place. Then put a shop towel in between the piston and the pad. Pull out the bleeder screw. Plug the hole for the line, most of the time your thumb will do. Blow compressed air into the bleeder screw hole. The piston should pop out. If not try soaking the piston to caliper junction with Liquid Wrench or something similar.

The brake pads and shop towel are there to slow down the piston to prevent damage. You'll have to remove them to get the piston all the way out.

Steve

[frosty5011]

Or, if you don't have an air compressor handy,

Hook caliper, minus the pads, back up to brake line....ensure that the piston is covered/protected with a rag as described above, and then use the brake lever to pop piston out of the caliper. (Caliper, of course, cannot be mounted on the fork while doing this, because disc would be in the way)

[Anonymous]

Cool idea Frosty. I never thought of that.

[Anonymous]

Frosty's plan worked great. I'm not sure why the piston was so tight as it was in great shape when it finally came out.

The seal and boot also look great. Do I need to replace these?

[Anonymous]

Well, I'm kind of saftey minded about this stuff. I figure it's 24 years old and it's the only thing that's going to keep your face off someones rear bumper. Besides you already have it apart. So I say yes.
Steve

[Anonymous]

I need to rebuild my rear brake caliper. I took it apart and one of the rubber seals (o rings) has gone bad. So I am going to get two new ones and what else should I get to rebuild.

[frosty5011]

I need to rebuild my rear brake caliper. I took it apart and one of the rubber seals (o rings) has gone bad. So I am going to get two new ones and what else should I get to rebuild.

That should be all you need, Donald. As long as everything else, like the dust boots and pistons etc, are still serviceable, then you should have it covered.