Grease gun method for stuck calipers

Just looking for a little feedback as my first attempt at getting a stuck caliper piston out with a grease gun was pretty lackluster.

First off, the grease gun didn't make a great seal with the bleeder valve and a decent amount of grease was leaking out before I really started leaning into it to make a better seal. After that I don't think any leaked.

I didn't buy a fitting but the gun snapped onto the valve really solidly so I figured it was a good match. Am I stupid for not getting an 8mm fitting or will that not necessarily work better?

I ended up running out of grease right as I was starting to build up some good pressure (small grease gun), though it seemed like it should have been enough to start moving the piston. The handle was getting much harder to pull on the gun.

Should I be having a crisis in confidence and try something else or should I plunge ever forward with this method with more grease and possibly a better fitting for the valve? Is the compressed air method possible with all this grease in the caliper?

 

If you ran out of grease, there's the problem. If you're not getting a good enough seal, there's your other problem. If it doesn't move under full-on hydraulic pressure, it sure isn't gonna move with air pressure. And, if it did happen to go with air pressure after being that stuck......I sure hope nobody, and NOTHING living or IMPORTANT is the 'line of fire' cuz that suckers gonna fly. THAT is why I prefer grease.

Dave

 

Deffinately NO AIR PRESSURE at this point! The pressure build up is likely to damage the casting as well as create a major mess. A CDC suit, and disposable tarps would be highly recommended if you chose to proceed.

It is not likely that you will get a good enough seal with the brake bleeder screw. I would switch to the proper grease fitting, and move onward.

Ghost

 

I dismantled the grease gun clamp and screwed this directly into the caliper after removing the bleed nipple, same thread. some minor leakage but a few pumps and the piston was clearly starting to move.

This worked on both calipers which had been sitting siezed onto the brake disc for best part of 10 yr.

 

it's the 4th of July coming up, use steam

 

i just stick a towel in the caliper area and use a quick shot of air, pops it out everytime, works on any brake caliper

 

No it doesn't. I've had numerous XJ caliper pistons that compressed air wouldn't budge.

If grease didn't work, your grease gun is wimpy. No offense, but using grease is just as "hydraulic" as the original brake fluid and really not compressible. If you got the caliper full and continued to pump with no result, either you got an air bubble or the seals inside the grease gun weren't up to the task.

 

Tried hooking it up to the brakes giving it a bleed, and push it out with the brake lever?

 

Thanks for the helpful replies guys. I ended up getting it out by trying the grease gun again. Put more grease in the gun and this time I really pushed against the bleeder valve to ensure a solid seal. Didn't take long before it started moving. Such a good feeling!

Unfortunately this piston was too badly pitted to re-use so a replacement is on its way. Once this caliper is back on and the brakes are bled the bike is good to go! Already rebuilt the MC, installed braided SS lines, inspected the rear brake, changed out all fluids, and more.