Cylinder stuck inside caliper, how do I free it?

That baby is in there.

Any ideas on how to loosen it up without destroying it.

Thanks for any ideas.

 

Sometimes you can remove the pads and then squeeze the brake lever. Either that or remove the banjo bolt and blow compressed air into the caliper. WARNING! Watch for flying piston. It would be a good idea to place cushions to catch said piston so it doesn't get damaged. If that doesn't work, heating the caliper body may be the answer.

 

You may need to spray some brake cleaner on the piston to loosen the gunk that has it stuck. If it is cocked or not straight in the cylinder and jammed then place a board across the width of the piston and compress the brake against it. This will keep the side that is farther out from moving and force the low side up to match.

 

Thanks for the replies, gentlemen!

I'll give it a shot.

 

I know this is well after the fact but when I have had to get cylinders out of brake claipers that are REALLY stuck I just use a grease gun and pump it out. The grease gun can develop a hell of a lot of pressure and the pistion does not go flying.

 

Yeah but then you have a caliper full of grease that you have to clean up! That just seems like a huge waste of time and its probably dangerous if you don't get it all out of the passages, since grease is a contaminant. Just use compressed air. Put a block of wood into the rotor/pad slot to keep the piston from flying out and smacking metal. DO NOT HAVE YOUR FINGERS ANYWHERE NEAR THE PISTON WHEN YOU APPLY PRESSURE!! IT WILL CRUSH THEM!!

I've done this many times. It takes a few seconds instead of the hour or so you'll spend cleaning grease out of everywhere :roll:

 

Oh, and warn your significant other that there may be a sound like a gunshot coming from the garage and let them know that NO, you are not finally killing yourself after working on your bike so much.

My wife about killed me after I did the compressor trick on my buddies caliper.

 

if it's real stuck and air doesn't work, a grease gun develops 10,000 psi
it will come out, like Dunk said

 

I'd rather hook the caliper back up to the master cylinder and start pumping and topping it off before I put a grease gun anywhere near it. The master cylinder will generate about 2,000 psi. I've never seen a piston THAT stuck. If it is, you might as well bust it up and get a new one because there's something wrong with it.

 

what will busting it up accomplish ?
always use eye protection

 

I had to have my calipers pressurized up to 8Kpsi to free up some stuck pistons. Took it to a hydraulic test cell and let them work the magic. Had to build up an adaptor but otherwise, they came out finally. New pistons on hand helped ease things along.