Stuck caliper pistons

Getting the inner piston out of a "clam shell" caliper usually rings the death knell for the caliper, especially after you have soaked the caliper in penetrating oil, heated it modestly and tried to add compressed air; sometimes they can be extracted and mostly they can't. I found a solution that has worked 4 times for me; it is still a bit arduous, but the satisfaction is amazing. I found this tool all over the internet and with one modification it works like a charm.

http://d2pbmlo3fglvvr.cloudfront.net/pr ... ufo5oy.JPG

This is called an internal pipe wrench. The two "plates" are held on by a spring clip, remove it and discard it. The center circular pipe grabber needs to be cut down so that the tool will fit inside the caliper bore, once you have removed the outer piston (I'll come back to that). You should still use plenty of penetrating oil, but you shouldn't need any heat. Simply drop the tool into the inner piston bore and turn until it locks with the piston, have a 1" combination wrench handy and get the piston turning the more it turns the easier it gets, at some point start applying upward encouragement and you'll see the piston rise, once it gets above it's seal it will fall out.

The outer piston: I have found that pushing it inward past its seal, then removing the seal pretty much does the trick; be aware while extracting this part that you keep the piston as parallel to the bore as possible, with penetrating oil it too should just about fall out, a little screw driver action may be needed.

If you promise not to laugh I'll explain as I do.
Fill with water the piston and soak a small rope that comes out from both sides.
Put all in the icebox in minus twenty degrees.
When it's icy pull hard on both sides of the rope.
The piston will come out!
Ciao
Piero

Or .....
http://m.ebay.it/itm/390939533780?_trks ... mwBanner=1

pierodn said:

If you promise not to laugh I'll explain as I do.
Fill with water the piston and soak a small rope that comes out from both sides.
Put all in the icebox in minus twenty degrees.
When it's icy pull hard on both sides of the rope.
The piston will come out!
Ciao
Piero

Click to expand...

We need pictures of that one! I love home-brew remedies such as this, and I promise I will not laugh!

Nathan

Re: Stuck calpier pistons

I did this only a few days ago - I must have been one of the lucky ones, as I found that plenty of compressed air and a blowtorch eventually released it. It took some doing though - neither of my smaller compressors were up to the job as too much air was leaking past the end plug (it wasn't in very far). A combination of more air and more heat did for it in the end though!

the method I have heard of to unstick caliper pistons adapts a grease gun to the caliper to press out a stuck piston with the hydraulic pressure of the grease gun. You cover the piston that isn't stuck with a steel plate and clamp the plate so the piston won't pop out of it's bore, then pump up the grease gun so the pressure is applied to the stuck piston side of the caliper until it pops free... I always thought this was a commonly known trick...

If you are using compressed air it generally blows the side that the line runs into out but not the other. Then you are left with an open port and no way to pressure up the other side. What I did was jam a plastic golf tee into the open port and hold it in with a screw driver. With some heat and then Freeze-Off the other side eventually came out. Watch your fingers!

I second the grease gun method. Works a dreaml but messy.

Re-connect your caliper to a working master cylinder with whatever brake hose you have that is known to be in good condition, bleed it.

Place a thin steel plate against the outer puck and stack washers in the front and rear gaps to hold it in place (keep them clear of the path of the inner puck).

Warm up the caliper with a blow dryer or small torch flame. As soon as it's as hot as it gets with the blow dryer, or too hot to hold, set it down and point a computer air duster (upside down) at the inner puck and blast it to chill it.

Next, just pump that inner puck out of it's bore. Should pop free after a pump or three.

Done, with no grease to clean up.

grandpaul said:

Re-connect your caliper to a working master cylinder with whatever brake hose you have that is known to be in good condition, bleed it.

Place a thin steel plate against the outer puck and stack washers in the front and rear gaps to hold it in place (keep them clear of the path of the inner puck).

Warm up the caliper with a blow dryer or small torch flame. As soon as it's as hot as it gets with the blow dryer, or too hot to hold, set it down and point a computer air duster (upside down) at the inner puck and blast it to chill it.

Next, just pump that inner puck out of it's bore. Should pop free after a pump or three.

Done, with no grease to clean up.

Click to expand...

Agreed, that is a good method. I used air, however, because I didn't have a convenient master cylinder to use. Also, I would prefer to have air all over my hands than brake fluid! I simply made a union which allowed a PCL airline fitting to go onto the end of an old brake hose. By fitting a spare piston into the outer part of the caliper and then blocking it in place with some convenient pieces of metal, the inner piston had no choice but to come out if I could get enough pressure/heat on it. Fortunately for me, it gave up before I did!

I just drilled a small hole in the backside of the caliper to knock the piston out with a drift and later tapped it for a set screw which I covered with a small dab of epoxy. Would be easy to remove and do again if it ever becomes necessary.

Danno said:

I just drilled a small hole in the backside of the caliper to knock the piston out with a drift and later tapped it for a set screw which I covered with a small dab of epoxy. Would be easy to remove and do again if it ever becomes necessary.

Click to expand...

I've seen that done a few times. No good for a clean restoration.

GP using the term "clean restoration"
that may be the funnest thing i've seen all year :roll:

grandpaul said:

Danno said:

I just drilled a small hole in the backside of the caliper to knock the piston out with a drift and later tapped it for a set screw which I covered with a small dab of epoxy. Would be easy to remove and do again if it ever becomes necessary.

Click to expand...

I've seen that done a few times. No good for a clean restoration.

Click to expand...

mikegray660 said:

that may be the funnest thing i've seen all year

Click to expand...

Glad I could bring a smile to your face. Happy New Year!

(some people grow)

I've used the grease gun method. The advantage is that the grease gun develops lots of pressure but as soon as something moves it drops to nothing so things don't move with explosive force like they do with compressed gasses.

grandpaul said:

Danno said:

I just drilled a small hole in the backside of the caliper to knock the piston out with a drift and later tapped it for a set screw which I covered with a small dab of epoxy. Would be easy to remove and do again if it ever becomes necessary.

Click to expand...

I've seen that done a few times. No good for a clean restoration.

Click to expand...

If you're really anal about those things, you could have a good tig welder fill the hole and then polish it before you reassemble. Only your friends would know unless you didn't tell them either.

Danno said:

If you're really anal about those things, you could have a good tig welder fill the hole and then polish it before you reassemble. Only your friends would know unless you didn't tell them either.

Click to expand...

I drilled a hole in the center of the piston, and tap. Then you can either use a slide hammer to tap it out or you can run the screw in so it butts against bottom and pulls it out.

Yes to that. You are not going to re-use the stock piston(s) anyways , so tap it to pull out and discard. Fit the new seals and stainless pistons.

The stuck piston I poked out through the drilled hole was hopelessly rusted and had to be replaced, but the Titanic's stuck piston came out with air pressure and is fine. No holes for my 'correct restoration" such that it is and the purists and the rivet-counters probably think the SS clone is an abomination anyway.

Use air!