Brake Pistons Stuck During Rebuild

[Brozoar]

Howdy,

So I'm rebuilding a pair of calipers and I ran into a little issue. I lubed up the cylinders, o-rings and pistons with brake fluid, started to slide the pistons in, and they got completely stuck (in the wrong orientation). And for the life of me, I can't get them unstuck.

I figure it's just because the o-rings are brand new and have some compressing to do (is this normal?), but I still need to get the pistons out so that I can rotate them to the right orientation. Any ideas? And when I say that they are stuck, I mean that they are STUCK stuck. I (stupidly) jammed an eyeglass screwdriver into the threaded hole for the brake line at the back of the cylinder and hammered until the screwdriver broke.

The best idea that I've got so far is to buy a long bolt with the same threading and diameter as said brake line hole, and drive it in to push the piston out from behind. Is there any way that could backfire?

Thanks.

[Gawernator]

I don't know a lot about the calipers. But I'll say that this really sounds like something I would do. Lol

[9FF]

Its an na right? Dont bolt it to the rotor, just connect it up, bleed and step on the brake pedal, it will pop out and with some force so be careful. Use some old cloths wrapped around to stop it flying out across the floor. Note: This method won't work on the turbo caliper.

I wouldn't screw a bolt in the back in case you strip the threads, which you probably will do if it's that tight.

There is a set way (orientation) to fit them, it's detailed in the manual.

[Volhv]

If you have an air compressor.... even one that plugs into the cigarette lighter, you can use the compressed air to shoot them out. Like 9FF said, they will come out quite suddenly once they break free.

[zedsn]

I have used a grease gun in the past where air hasn't worked. you will need to clean all the grease out of all the cavities when done but it will work like a charm. You will need to plug all line holes but the one that you are using and you might have to downsize or upsize the threaded hole for the grease gun line. I did this on some frozen calipers on my porsche 356 and it worked out great.

[John_AZ]

If you are just trying to achieve the 20 degree angle you can turn the piston inside the caliper with a caliper piston pliers or substitute?



Remember to use the 20* directions for Disc Brake Behind Axle
J_AZ

[Eric_Shea]

Send them to me... I'll pop them out for you.

USPS Flat Rate Box.

[Brozoar]

Originally Posted by Gawernator

I don't know a lot about the calipers. But I'll say that this really sounds like something I would do. Lol

Thanks, that makes me feel better.

Originally Posted by 9FF

I wouldn't screw a bolt in the back in case you strip the threads, which you probably will do if it's that tight.

Thank you, that's exactly the sort of invaluable foresight that I lack most of the time!


Well, I'm pretty ill-equipped in my apartment.. I was planning on finishing rebuild and then handing them over to a shop for installation/bleeding. It's just less opportunity-cost to me, since everything seems to take me about five times as long as the rest of the Porsche community.

So using an air-compressor or hooking up the brake lines and mashing the pedal (that idea also crossed my mind) aren't really options for me to do myself. Might just hand it over to the pros and let them finish my rebuild.

*sigh* So much for doing my own maintenance. Oh to be young and a renter.

[Eric_Shea]

Send them in... I'll help you. Just pay the freight.

www.pmbperformance.com

[Gawernator]

Originally Posted by Eric_Shea

Send them in... I'll help you. Just pay the freight.

www.pmbperformance.com

One of your coworkers/employees's son is in the Navy also and went to school with me!

[Brozoar]

Originally Posted by Eric_Shea

Send them in... I'll help you. Just pay the freight.

www.pmbperformance.com

Thank you for the offer, that is starting to look like the best route. Shops, man. Woof!

I'll let you know when I figure out how to ship them and they're on their way. I trust that you won't just, you know, keep them...

Thanks again!


P.S. All, could it have been that I worked a small amount of ATE Plastilube into the o-rings before rubbing them with brake fluid? I can't remember where I read to do that, but that stuff really seems quite sticky.

Edit:
Effin' d'oh. Quick question on Plastilube

[Eric_Shea]

Use the USPS Flat Rate Boxes.

Nothing I like more than a grungy pair of calipers hanging around the shop... yeah, we might just steal them, ya never know.

[Brozoar]

Well I'm going to avoid having to spend the money to ship if I can... If I don't have them out by Monday I'll send them along.

But I realized I do have access to an air compressor through work. The only thing I can't figure out is what kind of bit I'd need to hook up to the calipers, and searching the internets is seriously irritating me. I swear, you would think that out of all the hundreds of people who have done this before, someone would have posted the answer by now.

I went out and bought a rubber nozzle tip thing, but I'm concerned that won't really give me the seal I need. I think the brake lines are threaded @ M10? What does that convert to in inches?

Thanks...

[Devil Dog Mosport]

Originally Posted by John_AZ

If you are just trying to achieve the 20 degree angle you can turn the piston inside the caliper with a caliper piston pliers or substitute?



Remember to use the 20* directions for Disc Brake Behind Axle
J_AZ

Where is this page from? Where to buy these tools?

tku
Rich

[John_AZ]

Baum Tools

Catalog PDF 4 U.

http://www.baumtools.com/pdf/Porsche_Cataolg.pdf

http://www.baumtools.com/pdf/MB_Brakes.pdf

Pliers very expensive-improvise (Big Channel lock?)

J_AZ

[mreid]

Fold a piece of cardboard and slide it Into the caliper. Install the rubber tipped air nozzle on the compressor hose, hold it tightly to the brake line hole, and give it a couple of blasts. It should pop right out.

[Eric_Shea]

M10 x 1. It doesn't convert to inches. Depending upon how "stuck" you have them, air may not work at this point. It "should" but, if it reaches it's compression limit and the pistons don't come out, you'll need fluid. We use water.

Rich, you don't need any of those tools shown there to do a proper brake job. E.G.: the piston turning tool will rarely work if the piston is completely it the bore. It usually succeeds very well at maring the tops of your pistons (not as well as the suggested channel locks but...). If it is in wrong then it was put in wrong in the first place (they don't wander) just pop them out and set them properly... which leads us to the angle tool. This is the biggest waste of money and the most often misunderstood process. The pistons are already cut for a 20 degree notch (if they even have a notch). All you have to do is align the bottom notch in the very center of the pad cavity and the rest is done for you. It's very simple and you can do it by eye. Hope that helps save some loot...

And again, please... Do not use big channel locks on brake caliper pistons that have been improperly installed. Just pop them out and reinstall them properly as mentioned above. These are your brakes gang.

[Eric_Shea]

Here's a Facebook link from last year that may help:

https://www.facebook.com/media/set/?set=a.10151078936368193.430836.72240238192&type=3

[John_AZ]

Brozoar,

Can you take a picture of the caliper and piston? I want to see what you did.

If you do not want to ship and take advantage of PMB/Eric's offer, why not take the caliper to the local "Brakes Plus" or similiar shop? It should just cost a few dollars, less if your mother or girlfriend takes it in and explains with rolled eyes that her friend needs help.... Males at the counter are suckers for sweet talk.


Eric,

Great photos and professional work shown on the FaceBook link you posted and nice web site:

http://www.pmbperformance.com/calipers.html

J_AZ

[Brozoar]

Well, I'd be happy to take pics, only there isn't a whole lot to see. I lubed the pistons and cylinder walls with brake fluid, they slid in just fine without the seals in there (and I didn't use honing stones, but I did clean out the cylinders with a cleaning pad followed by progressively finer sandpapers). And then after I rubbed some ATE into the seals, then lubed them with more brake fluid, I popped them into the groove and shoved the pistons in, in just any old orientation without first rotating them to the proper angle..

It's important to note that it's entirely possible that they are not "stuck", that I just can't get enough force or leverage to slide them out. I've not tried the air compressor yet as I was too discouraged by the failure of everything else. But they're not going on the car immediately anyway, so no worries.