Stuck Front Brake Caliper Piston!! HELP

[OpFlash]

Hey there actually started working on my xj1100 today. had recently pulled both front calipers first one i worked on went together just fine. front right one is a pain in the ass. the piston is stuck something fierce! Ive tried. blowing air through the passage where the banjo bolt goes. even the bleeder screw passage. i used some wd-40 and some brake fluid (not too much) in an effort to loosen the damn thing. anyway i tried to get creative by wrapping duct tape around a socket close to the diameter of the piston and kinda wedging it in and using an air ratchet trying to loosen it by getting it to spin. i tried lightly pulling on the rim of the piston with pliers. i didnt get too crazy with this as i dont want to damage the piston. its soaking with a bit of wd-40 round the rim of the piston overnight. is there any advice or help out there. whats worked for you?? Thanks again

[missinglink]

I got a stuck piston out once by using an old master cyclinder. I went through all the things you mentioned until frustration set in. The only thing I managed to accomplish was to push the piston further into the housing. Then I bolted an old MC and brake lever to a piece of pipe, ran an old brake line to the caliper (I had removed it from the bike) bled the line and then squeezed like hell....the piston popped right out. Good Luck!

[OpFlash]

I actually can see there is a little ammount of room for the piston to go back into the caliper. I saw this while looking through the passage where the banjo bolt goes. I did try to hit it down earlier tonight but didnt really give it a good whack. I would like to try your idea but dont have access to those old parts im wondering if i put that caliper back on my xj1100 if it might push it out. is there any harm in trying this if its stuck will the pressure possibly blow out the seals or something like that on the master cyllinder??

thanks again!

[Winterhawk]

If air can't cut it, pump it out with a master cylinder. lay a rag over it for the explosion of fluid...LOL. If it really badly stuck drill a little hole in the end and push it out with a punch. Need a tig to weld the small hole up.

Get a aluminum welding rod and mash the end of it as to fit in the groove where the square o-ring was and scrape it clean. The rod won't scratch the caliper. Take a razor blade and carefully scrape all four sides of the square o-ring. install, bleed and have fun.

[LoserShoes]

Heat the caliper with a heat gun or small torch. The caliper is aluminum and the piston is steel, caliper will expand more than piston. Heat it to just a bit to hot to touch.

Steve

[fxrer]

I screwed my front caliper, with stuck piston, into the rear brake hose and pumped it out with the rear brake mc.

[xssiveone]

You can also use grease. Screw a plug of some kind into the bango bolt hole and a grease fitting into the bleed screw hold and pump the grease into it. Safer then air as it's more controlable.

[OpFlash]

Hey guys went at it again with the stuck piston. ok heres what i did i hooked the caliper back up to the front master cylinder. the piston did move forward but not enough to push it out all the way. I thought that it was gonna be loose enough for air. air pushes the piston ever so slightly but because its not a perfect seal it cant push it any further. the rear master cylinder sounds like a good idea. Im gonna try that and hopefully that will do the trick. I kinda like the idea behind the grease gun but would that produce enough pressure to push it out? if that doesnt work ill try heat with torch. I did however use very HOT water I dont have a torch. and that really didnt help much either. Thanks again guys...

[John]

Grease Gun

A grease gun with a good, snug fitting coupler will latch onto the bleeder screw of these bikes. I had to do that to two calipers that I had had bought as spares. The pistons were trash, so I had some new ones made up. I have also had to do this with some auto motive calipers. A grease gun will generate over 1000 psi of force.

[LoserShoes]

If you have the piston moving, shoot some penetrating oil into the caliper, then push the piston back in with a c-clamp, then try air pressure again. Once it's moving a little you pretty much have it. You just have to get a little lube between the piston and caliper. Might have to do it a couple of times, but it should come out.

Steve

[thuffman]

perseverance and penetrating oil

I tackled this problem yesterday on my LH rear master cylender and eventually succeeded using quality penetrating oil, bench vise and a friend's air compressor. Much lower air pressure than m.c. pressure, but I was not convinced the "unified braking system" used in '81 wouldn't just shunt all the pressure to the front caliper. Just refrain from whaling on it with sharp objects..
Tim.

[OpFlash]

John youre the big winner THANKS!

Hey there guys just got back from the basement workshop with much success. The piston is out YES! I just hooked up my grease gun and blocked the other passage with a solid bolt of the same thread type and gave her a few good pumps and she came right out. Ok next question whats your best guess at getting the caliper clean and as far as the caliper seals im sure that theres grease behind them i cant afford to ruin the seals as ive been unable to find them anywhere. Anyway the piston looks ok but you can tell where it was stuck may clean up with some fine steel wool. what do you all think

thanks again

[DiverRay]

Plenty of brakeclean for the caliper, once the seal has been removed. You really need to try and find a new seal, if possible!
The piston I would clean with parts cleaner and one of the plastic scrub pads. You don't want to scratch the piston, as that will be a leak. Follow the advise on cleaning the seal grove, and you could use the plastic scrub pad on the inside bore of the caliper. Just have plenty of brakeclean handy.
Once everything is clean and dry, lube the inside bore and the piston with new brake fluid and put it all back together.

[OpFlash]

Ive done pleanty of searching a while back on the caliper kits for the xj1100 ive been able to find only the rear kit. ive seen lots of front end kits for the xs anyone know if they are identicle to each other

[skids]

Re: John youre the big winner THANKS!

Kerosine seems to be pretty good at removing residual grease!

Originally posted by OpFlash
Ok next question whats your best guess at getting the caliper clean and as far as the caliper seals im sure that theres grease behind them i cant afford to ruin the seals as ive been unable to find them anywhere.
thanks again