Stuck Piston in Brake Caliper.

[rwest]

Hi,

Both of my front calipers have one stuck piston, the outside one. The ones closest to the brake line move out easily with the compressed air. I clamped those down with a clamp and have had no luck getting the others to budge. The old pads are worn unevenly, so I assume that they weren't moving very well under pedal pressure either. I did a search and didn't come up with anything new to try. I was thinking off trying to apply heat to the caliper to see if some expansion would help, but thought it might be smarter to ask you folks first! So, does anyone have a good method or had luck using a plumbers torch or oven to heat them up?

Thanks, Rutager

[Kidasters]

My guess is that there is corrosion inside of the caliper from far too infrequent brake fluid changing.

I don't know if heat is what I would try. Not only would it probably not work, but if there is any brake fluid left in there - the fumes might be bad.

Soak it in PB blaster, Liquid Wrench or other penetrating oil. Something I've done to remove a stubborn piston is, after soaking, grab it on the edge with a very small pipe wrench (like 6"), and just start it rotating. If you can get it to turn, it will come out. Of course - it will also ruin the piston, but if my guess is correct, you are going to have to re-build the calipers anyway.

Good Luck.

[pete3799]

Soak with PB Blaster or similar then push them in with a clamp.
Apply air again repeat as necessary and eventually they should pop out. Make sure to keep your fingers out of the way.

[LakeCleElum]

Found a tip on here that was the only way to get the pistons out of my '69 that had set for years.

Clamp the one free piston. Unscrew the bleed screw. Take the fitting off your grease gun and the bleed screw threads are the same. Attach grease gun and start pumping. Hydro pressure will force it out very easily.

I had hesitated on this thinking the grease inside the caliper would make a big mess. Was no big deal at all.........g'luck

[john walker's workshop]

hang it back on the brake hose, bleed and use the pedal to move it.

[Joeaksa]

Either do what John says above or put a "C" clamp on the one that moves and hook a grease gun up to it and pump slowly.

Using air pressure can cause you to walk away with one less finger... its up to you.

[GeorgeK]

Fill the caliper with brake fluid, with the moving piston extended.

Place a bleed screw where the brake line goes.

Close the bleed screws

Squeeze the moving piston in with a C clamp.

[Zeke]

Originally Posted by Joeaksa

Either do what John says above or put a "C" clamp on the one that moves and hook a grease gun up to it and pump slowly.

Using air pressure can cause you to walk away with one less finger... its up to you.

I don't know about that. Using air pressure is scary alright, but once you put the air to the caliper, you should have th clamp in place and a rag between the pistons to soften the blow and contain the piston when it comes out.

In fact, I wrap the whole thing up in a towel after I get the rubber nozzle in place. Even better would be to have the air hooked up with a line threaded into the caliper so that you could do this remotely. If you don't like the sound of a gun going off not knowing when it will fire, this method would help.

Anyway, grease will do the job, it's just a waste of grease. So use some cheap stuff.

[boyt911sc]

Compressed air works well with stubborn brake caliper pistons. But those really stucked brake caliper pistons have to use the brake hydraulic system. When rebuilding brake calipers, with all the calipers still mounted on the car I remove all the brake pads and insert wood spacers approx. half the tickness of the brake pads and pushed the calipers out. It might take another set of spacers to bring the pistons out to about 3/4 or more. C-clamps work better for this application. Once you have pushed the calipers out this much, they usually come out nice and easy. Keep us posted.

Tony

[rwest]

Hello Fellas,

Victory is mine/ours!!

I went back out to the garage after I posted, and added a bit of heat to the caliper with a propane torch, and it came right out! Stuck piston #2 didn't want to "play ball," so I tried adding brake fluid and then squeezing the good piston in with the clamp. The piston came part way out! But the clamp wouldn't fit to squeeze anymore, so I tried air again, but no luck. I then pumped it with grease, bingo!

Thanks to all for the great tips! I had my front end completely out so using the cars brake pressure wasn't an option, next time I'll make sure all the pistons are moving before I remove the calipers.

-Rutager