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OK I've been having a problem, or at least I think so, with my back driverside Caliper.

I took my mx out of being stored last week and this caliper stayed seized on the disc. It was replaced last year, and rebuilt in the fall. Now it will apply pressure (ie. piston comes out) but the piston will not go back in.

What other details do I need to give or what is the problem???? PLEASE this is urgent

Take the handbrake assembly parts off and clean them up real well. Then grease them up like theres no tomorrow and slap it all back together. When you store it next year be sure to just leave it in gear with a brick behind the tires. Or better yet put it up on jackstands.

when I did my brakes they didnt push in either, but they screwed in , and they work. Give it a try maybe.

s---, now the piston is out all the way.. it is wobbling a bit... I tried turning it like you said and no luck.

I checked the rubber and it doesnt appear ripped and the piston itself is not rusty at all. Ill try taking off the handbrake assembly.

does it turn at all, push and turn

They will not push in. They turn to compress. Turn it clockwise and apply a it of pressure when turning. Be careful not to skip off and scratch the piston though. A scratch will cause a heat spot and ruin the caliper. (a small scratch is ok, but if you do scratch it try sanding it down with a sanding block) If it will turn and the e-brake isn't stuck it should retract.

ok, now I am the kinda person that hates not understanding fully, so here's whats on my mind:

Even if I succeed in retracting the piston back to it's original position.. what says it wont do this again?

What "sucks" the piston back into it's original postion when everything is hooked up (ex. when I let off the brake).?

How can I tell if the handbrake assembly is stuck? It seems to be in the retracted position... as far as it will go anyways.

Thanks guys, Ill try and twist some more when I get home this evening... I tried last night and it turned a bit and seemed to go in a bit, but I was doing it by hand and had limited force on it. Anyone have a trick to twisting while applying pressure?? Like a tool or something I can use?

*achoo*

The piston is pushed back in by the rotor run-out. The rotor has a slight wobble built into it which forces it back in. A vice, c-clamp or channel lock plyers should help you out.

There is a tool at the autoparts store for this
The one I got is a "universal" tool, it is a block that fits onto a socket wrench, with different shape "pins" on each facing (so you can find the facing that fits best). Using that, you have to push and turn the piston back into the caliper (screwing it in). If you've pumped it out (you have) this could be a lot trickier getting it to line up to screw back in, and doing so without tearing anything, I did this on my back passenger caliper (pumped it out by mistake), and did manage to get it back in, it literally "popped" back into the bore when it finally lined up properly, then had to screw it back in the rest of the way. I saw a spot of fluid when this occurred around the seal, but it has since had no problems at all, my guess is the pop was fluid pressure suddenly popping loose back into the system (something must clog a bit when it's pumped out).
Do all this with the master cylinder cap off (and fluid below full) of course to relieve system pressure and keep from overflowing the cylinder. Good luck, take your time and push firmly (not brute force, just firm) and turn smoothly.

here is the deal with brakes man . if ur sliders are moving freely when u have them assempled and mounted back on thats all u need . the pistons will push out and they do not need to be pulled back after you use ur brakes since once u let the pressure off of them they will move back on their own. when u have a caliper seized that means that the sliders are not moving freely it has nothing to do with the pistons. if u ever seen a brake job ull see the mechs using a big a-- plyers to push the piston back since it comes all the way out as ur pads are wearing out. make sure tho that ur hand brakes arent siezed but if ur only concern about the pistons moving back on their own then dont worry cause they will not go back

awesome dude thanks yea it turned out I needed to turn the pistons clockwise to return them back to their original position. All is installed, but now i have another problem... Need to replace a few brake lines..

PS arrent you on Redliners as well?

ya dood u gotta use a SST to turn them, but the tool is ridiculously expensive (180 when i priced it! fark that)

I used some needle nose pliers to turn it inwards. Should work for you unless its seized.

Gro Harlem wrote:I used some needle nose pliers to turn it inwards. Should work for you unless its seized.

Great minds think alike... and it worked awesome.. too bad I didnt think of that the first day!!