Front brake caliper question....

Okay wrench heads I have a question that I'm not sure if anyone knows the answer to and haven't seen a reference through Forum Search so now I ask....
Does anyone know if the caliper piston retreats flush ALL the way back into the caliper housing? My piston is extremely stuck and once I start working on it I don't want to get crazy and break anything. I haven't measured exactly but I'd say the piston is sticking out about 1/2" from the caliper housing.

Thanks, y'all are great!

'82 XJ650J Maxim - OEM

 

I don't have a 650, but, shouldn't you be working the piston OUT ? then clean, inspect, sand, polish, replace seals, re-install ?

There's this trick with a grease gun that's supposed to remove any stuck piston. I suppose it wastes grease.

 

*LOL* Yes funny man the idea would be to take it OUT. I've been reading some threads on it and if I can get it to go IN a little bit then it should come OUT. I'm okay with wasting some grease if anyone knows what that trick is.

 

no trick, just find a bolt to cap off the banjo bolt hole (10x1.25mm IIRC), open the bleeder valve slightly, put grease gun fitting on it, pump a few times... caliper comes out nice and slow. scoop grease out of caliper, clean thoroughly.. brake cleaner + paper towels ought to do.

 

what if a person was to close the bleeder, put maybe 2 tablespoons of water in the banjo bolt hole , plug it and heat it with a propane torch till the water
boiled, steam, big pressure, pop, hot water everywhere, be careful
did i just invent something ?

 

caliper cannon!

 

Y'all are aware the piston is REALLY stuck? I mean like it's been siiting 10+ years.
Are y'all setting me up for some horrific MythBuster scams?

 

how about an proper threaded solid bolt instead of a banjo, and maybe an oil to expand? Steam is fun too.

I have a caliper filled with marvel mystery oil, a solid bolt, and I put compressed air in via the bleeder hole (safety glasses and leather gloves on) trying to work the pistons out. I don't have a way to get a grip on the pistons.

I am contemplating unbolting the two caliper halves. Thoughts?

Back on my 70's Volkswagen, I always heard to never separate the halves, but for lack of parts we did even mix and match halves when we found cracked parts.
Original machined halves and no sealant on any surface, bolted back together, never had a leak. Tons easier to clean the grooves and get the pistons out and in.

 

the grease gun trick worked for me on my 550, after 20 years of semi-outdoor storage. it also worked on my buddy's XJ1100 that sat for who knows how long. honestly, I don't think it matters how long it sat. something about hydraulic pressure of grease.. it's very persuasive... and anti-climactic. when you're done, it's like... "that was it?" :mrgreen:

 

As long as we're on the subject of grease guns (in a roundabout way) I have a question. This is ridiculous as I consider myself to be somewhat educated/mechanically inclined person but I bought this>>> http://www.harborfreight.com/cpi/ctaf/d ... number=219
Does anyone have one, how did you get it working? I've read the directions over and over but I think something was lost in translation from Chinese.

Thanks

 

OK, maxim82: my two cents...You have your gun attached to an air compressor pushing 30-100 PSI. You've loaded your greast cartridge, so it seems that once the compressor is charged up to whatever PSI you want, you just attach the grease fitting to whatever you're trying to lube up, and squeze the trigger. Is this what you've tried?

 

Yep it is. Says something about air in the gun and loosen air vent screw yada yada yada. Well that doesn't seem to do anything following the directions anyway.

 

stereomind>>> Many thank you's!!! Once I got my pneumatic grease gun working correctly I hooked that bad boy up to my caliper and it pushed the piston right out. And it was rather anti-climatic. I had a large sponge ready to stop the piston from flying and instead it just kinda went "bloop" and fell out. I'm stoked and ready to clean now!
Thanks again