Caliper rebuild: stuck piston --UPDATE Question!
 

Hey all,

Normal brake pad replacement on my SC. The left front side went in fine, but on the right front's inner piston absolutely refuses to retract! I mean that sucker will not budge with stiff prying/pushing, yikes!! So does this mean caliper rebuild? And if it doesn't want to budge now will I be able to get that piston out to replace the seals? Advice please! TIA, gents!

Edward

Yep, you have to rebuild the calipers. Do NOT split them, it’s not recommended or necessary.
I have managed to remove pistons with compressed air but there is a great risk that the piston fly somewhere doing damage. Also brake fluid can splatter everywhere.
Some have removed the pistons with grease gun, lot’s of pressure but more controlled. Not completely as air in caliper compress and can send the piston flying.
If the piston is really stuck you probably end up replacing all pistons. Check if rebuilt calipers are available.
I’m sure you find a lot of advice how to rebuild calipers with Google.

I had good luck removing stuck pistons with compressed air being directed in the hole the fluid normally goes into.
As Vane mentioned watch out for the fluid splatter. Recommend covering with some thick shop towels. Also put a thin piece of wood between the two pistons and dont have your fingers in there. When it does pop out it comes out hard and you dont want it slamming into the opposite side piston. The tricky part is you must have the other piston in there to escape all the air from just venting out the opposite side so the pressure can build up.
Order a rebuild kit from pelican or someplace. Very doable job. IF you are not into doing it yourself you can find rebuild calipers pretty easily.

When I had a rear seize up I was able to finally wiggle it free using pliers with a sheet of rubber cushioning the jaws. Not usually recommended, but the piston wasn’t damaged and I was able to rebuild it with the standard kit.

Mark

Good advice here. I did it with compressed air and the wood in between. You want it thick enough that the opposite side does not pop out
After mine came out i was able to clean up and reuse no problem
Pay attention to the fingers comment. It comes out wth enough force to stop a car

I am going through a brake resto on my 84. I pulled them all off and started the rebuild and cleaning. It was just a massive PITA. For under 700 bucks to restore and replate all 4 calipers, I decided to let the professionals do it. I just mailed mine off yesterday to http://www.pmbperformance.com/mid-911-brakes.html.

You can try to massage it a bit by lubricating the exposed section of the piston with brake fluid and using a c clamp with pieces of wood to push it in and air to push it out.
Do this a couple of time and it might start to move again so you can easily remove the piston and do a rebuild.

I've never not used compressed air.
Get a few thicknesses of wood and gradually blow out the pistons. If one comes out and the other doesn't, stick it back in and block it off so it can't come out.
I'd drain them first or the fluid will fly everywhere.
Easy job, although time consuming.

yup thst exactly how i did it , some wood and shims , and gradually removed shims till it popped out.

we usually use a grease gun, works every time

I almost included a comment like this in my previous post. I redid my complete system and it really challenged my love of DIY vs the amount of hours it took me vs paying someone else to do it. Ultimately I am glad I did it all myself but about 75% of the way through I might not have agreed. haha

You guys rock, thanks! I was half-hoping there would be an easier solution, but I guess I'm going in (just ordered a caliper rebuild kit ...and a rubber brake line just because I'm there).

FWIW, I did rebuild one of my fronts maybe over a decade ago, so the process is there, deeply rooted in some distant memory. But all these reminders are truly helpful! As usual to my RL brethren, big thanks, gents! You all rocketh mightily!!! :D

Edward

I had the rebuild kit and I had made an appointment with the media blaster. I just switched over to fixing my 997's AOS coolant leak. I have too many car problems going on. I really wanted them to be replated and done correctly. I have to drop the engine and do my fuel lines, clutch, etc next. I figured I will have enough DIY to last a life time....

replace all 4 of the rubber hoses (unless you did it within the last 15 years)

you may be able to use the pedal to push the piston out - that's easiest

compr. air next - wear eye protection

grease makes a mess, but works fine

may as well buy dust boots and seals now - my ('73 with Al '77 arms) had little clearance so you may want a low profile socket, etc.

I think using the pedals would be painful for my body. You would be juggling the caliper and then shims and now you have to push the pedal.

You don't need eye protection when using air. Just put a towel on top. Try not to jump when it pops. lol

Please don't tell me you guys are pumping grease into your calipers. Yuk.

Just my opinions being a .......