I am working on restoring a 1972 and am being told by my local shop that the pistons in a few of my calipers are locked and will not release. He told me that he tried air and even heating them, but nothing worked. Anyone have any tips? Do I need to replace them with new/used ones?

Any help would be greatly appreciated. Or if anyone has some at a reasonable price.

Thanks

i have had luck with a couple drops of water in the caliper, sealing off the bleeder and line with a bolt. heating up the caliper with a torch. when the water turns to steam, it will blow the piston out. keep a rag over the piston because it will fly. secure the first one that comes loose so it can't move and repeat on the other one.

Haven't tried that method. A grease gun will force one out as well.

To get them to move, use a big C-clamp and push them IN first.

Then I have used compressed air to blow them out but it IS violent and you MUST use backup blocks of wood and some rags or you will hurt yourself.

I like the grease gun idea because its a lot safer than air.

I haven't tried the grease gun method, but I would try that first in the future. I ruined a front caliper using the air method - the piston shot out violently enough that it sheared that centering pin the piston rides on as it exited the bore. I haven't heard about the water/steam idea before, but that's creative.

The problem is normally limited to the front, right? The rears you should just be able to crank out, I believe.

A grease gun works beautifully. I've done it plenty of times. Forces the piston out without a problem and is fully controllable (no explosive launch, like with air or steam). Only drawback is having to clean all the grease up afterward.

Find a zerk fitting that screws into the hole where the brake link attaches. Then, clip your grease gun to the zerk and start pumping. Once it starts getting hard to pump, you'll see the piston start to move with each pump.

A tip: go to the FLAPS and get the cheapest grease you can find. For this job, there's no reason to waste good grease, and grease quality won't make any difference here.

I like the grease gun idea; steam and air are in the same league, very dangerous.

i only suggest the steam method as a last resort, after grease or compressed air failed to yield results. it can be very dangerous if you are not careful, the piston does want to fly. i have had motorcycle calipers not yield to anything but steam expansion.

,grease gun is best have done it many times,compressed air is not that effective or safe,steam or heat ?..I just wouldn't go there.
A rubber flexible brake line will thread straight on to most grease guns.

It does fit but I would try the zert ftg as Bill mentioned. I believe any conduit that expands/contracts will store energy/force and we're right back to the dangers of using compressed air. Perhaps to a lesser degree. Also. the hose may not handle the force required and burst?

I am new to this, but the caliper should be seperated into two halves before trying any of these solutions correct. Where is the grease inserted? Should I pull the bolt directly behind the piston?

It's done with the caliper still assembled

as rory said, done while caliper is assembled, remove bleed nipple and replace with a metric zerk fitting. plug the line port with a bolt and push grease into the caliper from the zerk, hopefully this will loosen the piston. generally, one breaks free first. when that happens clamp that piston so it can't move and pump more grease until the other piston frees.

I did it once by separating the calipers first, but then I needed to make a plate to clamp the halves onto to get the air into the caliper half.
It worked, but since then I have always used the compressed air with them still together.
The way I do it without breaking anything is to use paint stir sticks between the two halves and push it out in small increments removing paint sticks between "pushes".
Then once you get one half out, you put it back in a little and hold it with a stick and a couple C-clamps while you do the other side.

I am fairly certain Eric is reading this and laughing at us - he probably has some fancy jig he puts them in...

Nah,none of those issues,ever seen a good brake hose burst???they (pistons) just don't seize that bad,as said I have done this many times before.

Grease gun is a great idea, never thought of that.

WOW ... I didn't think I was going to leArn anything today ... lol

The grease gun is a brilliant idea !
Tnks

The steam idea is good too, but I'd keep the calipers halves assembled for that, with a block of wood in the middle sized to prevent the pistons from escaping the bores.

Front remanufactured calipers are cheap:
http://www.partsgeek.com/p5nglzm-porsche-9...e+Brake+Caliper

I usualy treat those as good cleaned cores and check the rebuilt.
Please pay attention to bolts holding them together. 7mm hardware is not available anymore except in 8.8 cheese-like grade. You would probably want to keep the old bolts before returning the old cores for refund.