Sticky caliper pistons

[drola]

I am redoing the brakes on a '68 912 and at least one of the pistons in each of the calipers are not not budging. I tried heat, compressed air, pushing them in to loosen them up and nothing seems to work. I was thinking of putting them in the oven at 400 deg for a little while to see if that helps.
Does anyone know of a method or trick to getting those pistons free?

[Joe Bob]

Soak them for a day or two with Marvel Mystery oil or PB Blaster. Try compressed air again. Put a block of wood in between the pistons prior to applying air.

Heating them can be dangerous unless you have some real heat resistant gloves.

OR you can do it the easy way and do a rebuild exchange with Eric at www.pmbperformance.com

BTW, what psi is your compressor set at?

[Scott R]

Have you tried putting them back on the car without the pads and pumping the brakes?

[ajwans]

Grease gun. The fitting on the gun I used screwed right up to the intake. Plug the any other holes and you will have to clamp the non-seized piston.

This will generate a lot of force, keep fingers, animals, children clear. Put a block of wood in between like Joe Bob said.

It's messy but for me this was way safer than compressed air as the grease does not compress so there's no residual force behind the piston except what you are currently applying by squeezing the handle on the grease gun.

This assumes that you bleed them, if not there will be a small pop off when they finally slip out.

andy

[Joe Bob]

I've never done the grease gun route but I've heard it does work. It's a bit of clean up afterwards....but solvent bath will fix that.

Also if one side pops out and you can't the other to go....creative clamping in a vise will do the trick. Wood block up against the piston that moves, one vise arm over the block the other on the outside of the caliper....use a heavy shop towel over the outside of the caliper to protect it.

[drola]

Compressor is set at 110 or so. I use a c-clamp to hold the free piston and of course i use a block of wood in between. The grease gun sounds like a good idea, i'll give that a shot. But not tonight.....

[porterdog]

Man, I learn good stuff here.