Opel GT Forum banner

1 - 11 of 11 Posts

·
Member
Joined
·
102 Posts
Discussion Starter · #1 · (Edited)
How to remove seized piston?

I am in the process of rebuilding my calipers.
One of the pistons won't come out!

Any of you had a similar experience?
Any suggestions as to how to proceed?

Or am i going to have and replace whole caliper with a rebuilt from OGTS?

HELP!!!:eek:

(PS: I am using the air compressor as the manual states)
 

·
Super Moderator
Joined
·
13,845 Posts
Re: How to remove seized piston?

likengtj said:
I am in the process of rebuilding my calipers.
One of the pistons won't come out!
Any of you had a similar experience?
Any suggestions as to how to proceed?
They always stick. Usually rust/sludge. I had made a fixture to pop them out, using a master cylinder mounted to a bench with a hand lever to actuate the master cylinder. I had a short brake line I threaded into the caliper, and a spacer block to keep the pistons from launching across the room.

My alternate method was a grease zerk brazed to a brake fitting. I'd thread the custom fitting into the caliper, and then pump grease into it. Pistons moved.....every time. The obvious down side to this is the grease contamination. But, I have my own technique for successfully splitting calipers to allow full cleaning after the pistons were removed. Can't disclose how exactly for liability reasons, but it's never failed me yet.

Bob
 

·
Registered
Joined
·
2 Posts
how to remove stuck pistons from calipers

I know this may sound unorthodox, but hey, it works! I drilled a 1/4" hole in the back of the caliper through to the center of the bore. Then using a punch was able to drive the piston out. I cleaned out the rust and corrosion from the bore with a rotary sandpaper "flapper" with very fine sandpaper and finished polishing with ultra fine emery cloth by hand. When piston was free in the bore I tapped out the hole I had drilled and, with thread sealant, installed a brass pipe plug to close the hole. I reassembled the caliper with new seals and it works perfectly. This was 2 years ago and I've had no problems. P.S., I did NOT split the caliper halves!
 

·
Member
Joined
·
149 Posts
I use a front master cylinder to a motorcycle with a custom made line and a small chunck of handlebar. Works just like a little had pump and inches the piston out easily and safely. Just makes a huge mess if you accidentally knock the whole thing over just after you have removed the piston. :eek:

Darrin
 

·
Opeler
Joined
·
13 Posts
How to remove stuck pistons

I have been learning a great deal from these forums (thank you everyone!) and finally have something to contribute. I rebuilt my calipers a few weeks ago and after I had the first one off the car, I could not get the pistons out. I tried an air hose, as the book suggested, but couldn’t get nearly enough pressure. So I ended up reconnecting the caliper to the brake line and pressing the brake pedal. One of the pistons shot right out. Then I clamped a 2”x 2” x 1/8” flat piece of rubber, with a large round washer behind it, over the empty cylinder to seal it. Refilled the brake fluid, pressed the brake pedal, and the second piston popped out.

For the second caliper, I went through the same procedure before removing it from the car, and both pistons were out in under five minutes. The only downside was a little more wasted break fluid, but it was well worth it.
 

·
Member
Joined
·
296 Posts
i got my calipers off and am now rebuilding them. mine were stuck too. my dad got them out with the air hose at 12bar. it was a hell of a bang when those things shot out. but now the thing is. calipers look good but the piston is not so good. so went out to look for new ones. but i can't find them. anyone know where to get them? or maybe have some good ones laying around?

post a pic of it later.
 

·
Opeler
Joined
·
1,505 Posts
I remove my caliper pistons with compressed air in the inlet port of the caliper but they sometimes fail to come out at the same time. So I replace the first piston to come out with an expanding rubber freeze plug and re-apply air pressure to the caliper and then the stubborn piston will come out. WARNING:
Keep your fingers out of the caliper when using compressed air as the pistons come out with a lot of force.
 

·
Super Moderator
Joined
·
8,205 Posts
SpringGT said:
WARNING:
Keep your fingers out of the caliper when using compressed air as the pistons come out with a lot of force.
I insert a piece of wood between the two pistons to stop them from coming completely out. This way both pistons come out far enough that it is easy to get them out the rest of the way. I usually find an old scrap of hardwood flooring laying around the thickness is just about perfect. Just stick the scrap in far enough that if only one piston moves it won't come completely out before being stopped.

HTH,
Harold
 

·
Member
Joined
·
187 Posts
rebuilding calipers

But, I have my own technique for successfully splitting calipers to allow full cleaning after the pistons were removed. Can't disclose how exactly for liability reasons, but it's never failed me yet.
Why exactly is it that manufacturers and distributors always tell you not to split the two halves of the calipers? If you clean them properly and replace the seal between them. Then make sure you put the same two halves back together again, torqued properly i don't see any issues. I have done this on several sets of calipers and never had an issue.
 

·
Vendor
Joined
·
2,428 Posts
The "secret" is the square shouldered O-rings between the halves. They're supposedly impossible to find, however I know of one member here who has managed to source a suitable replacement. If you do not have the right seal between the caliper halves you're endangering your life, so proceed with caution!

Todd
 

·
Opeler
Joined
·
54 Posts
this is why this is a great site

This is great I am going taking the front brake apart this weekend and you all have answered and give me a couple of options to rebuild the calipers.

Thanks
 
1 - 11 of 11 Posts
Top