Brake Caliper Rebuild

[Andy911sc]

I am going to be doing a complete caliper rebuild for an 82 911sc. I will be taking everything apart (even splitting the calipers in half) and getting things cleaned up and coated properly.

I have search the tech forum, but couldn't find much detail on the splitting of the calipers. If anyone has pictures or details for this, that would be great. I have rebuild kits for the pistons already, plus new bleeders and I am going to order new stainless pistons from PMB Performance.

What other seals am I going to need on top of that and what tool. It looks like a T-35 Torx, but I could be wrong. Also if I need special tools or other seals, where can I get these. I am going to ask PMB Performance if there are seals in between the two halfs and if there are do they sell them. I just have to wait for them to open to call since I am on east coast time and they are located in UT.

Any help and experience from you guys would be great. Thanks.

[KTL]

Yes there are o-rings between the caliper halves. The tool for the caliper sandwich bolts is not a Torx. It's called a ribe socket. Do a search here on the forums and you should find the information you're looking for.

That said, i'd have to ask why you want to split the calipers. Doing a full restoration?

[Andy911sc]

Yeah I am doing a full restoration. The car was sitting for 16 years. I removed some pistons last night and they are really pitted on the outer part, plus inside I noticed the brake fluid slugged up. So I want to do a full break down and re-coating. I am a chemist, so the re-coating I am not afraid to do, plus I have a full lab at my disposal. I just ordered the black oxide kit for the bolts but calipers I am debating whether to powder coat or zinc plate/black oxide. I am actually leaning towards a mix or black oxide plus red powder coating in certain areas. I also ordered the high temp vinyls for the porsche name to go on the outside.

I figured if I am going to do a full restoration, I am going to customize it a little.

I did a search and read a lot of threads the past two days, but couldn't find anything on the ribe socket, where to get it and the o-rings and where to order new ones of those.

[djdsc]

There is no reason not to split the fronts. Not splitting is an old wives tale that should be buried and forgotten as long as you have new correct seals. Even some of the pro rebuilders, touted here, use an alternative seal, flat and not an o-ring for their work.

[Goodie]

I'm not sure how much all the parts/tools will cost you to do them yourself but for under $300 PMB will ship two professionally rebuilt calipers(minus pads) to your door, ready to install. After being in your position, I opted to call Eric @ PMB andwas glad I did! I'm a pretty hard core DIY'er, but when it comes to brakes, I'll leave that to the pros. They do excellent work!
Either way, good luck with your project!

[Andy911sc]

That's what I figured about the splitting, that it was an old tale that you would never get them to seal again.

Logically if you have new seals and torque it correctly, then you should have no problem. My problem is finding the information I need, like which o-rings, torque specs and I think I read somewhere that there is a certain pattern to re-tighten the bolts correctly. If anyone could chime in as to where I can get all this info would be great.

[KTL]

Never said splitting was risky. As long as the mating surfaces are true and a suitable seal is used, there should be no issue with splitting. Plus, I think the splitting of the Ate iron calipers is much less of a concern than the later Brembos. The Ates use a bolted (nut + bolt) vs. the Brembos being a bolt threaded into the receiving halve. Plenty of opportunity for munged threads on the Brembos during disassembly.

My question was asked simply to know why he wanted to split them.

Here's some good info from the old timers. Brake caliper torque values

Looks like the part number for the inner seals is 901.351.928.10 You have to dig deeper than 1982 in the parts diagrams to find the seal. The diagrams changed after 1977 and in 1978 the brake section only shows a complete caliper- no more exploded view, except for the pistons & seals, pads and retainers.

[Andy911sc]

Well 300 for a pair, you are talking 600 by the time I am done plus shipping. Black oxide recharge kit cost me 20 bucks because I have done it before and have the containers. I have a full tool room/shop at the house at my disposal due to my dad being a tool maker. I already have the rebuild kits which was a total of 25. all new stainless pistons will run me about 140 and I am can get free powder coating from a buddy if I go that route. So, all I need is the socket and o-rings.

[Andy911sc]

thanks guys, keep the info coming. As I start to do this project, I am going to document everything here for future reference.

[blee]

I too was hesitant in splitting the calipers due to difficulty in finding the darn o-rings. After searching high & low, I contacted Eric (PMB) in Utah. Great guy - was nice enough to send me the o-rings and even provided lots of helpful information. I'm in the process of glass-bead blasting them now. Once cleaned, I'll send them off to get zinc plated. What is this black oxide kit you speak of?

[Andy911sc]

Caswell Inc. - Black Oxide Kit

that's the kit I already have, so I just needed to get recharge solutions. I have the 2.5 gallon kit.

[blee]

Is there a chance you'd be willing to black oxide my caliper bolts? I'd hate to purchase the kit just for this project.

[Andy911sc]

I talked with Eric at PMB. Really nice guy and helpful. I purchased his stainless pistons, the tool I need and the o-ring seals for in between the two halfs. He gave me the information I need on the torque and reassembly pattern. Just have to finish cleaning up the calipers and wait for parts.

[zippy_gg]

Originally Posted by Andy911sc

I He gave me the information I need on the torque and reassembly pattern. Just have to finish cleaning up the calipers and wait for parts.

So... would you like to share that information?

[Andy911sc]

Oh sorry, that would probably help wouldn't it. Remember this is for 911sc calipers A-type on the front and M-type on the rears.

For the front calipers:
1st round set the torque wrench to 12 foot pounds and number your 4 bolts across. "1,2,3,4"
Tighten order: 2,3,1,4
2nd round set the torque wrench to 29 foot pounds and use the same order.

For the rear calipers:
1st round set the torque wrench to 7 foot pounds and use the same numbering system and order.
2nd round set the torque wrench to 17 foot pounds and repeat.

He also mentioned to only put the torque wrench on the hex nut and use the ribe bit to hold the bolt only.

Hope this helps guys. And, as I dig into this rebuild I will take lots of pictures and document everything.

[jrolstin]

Subscribed. I just ordered rebuild kits for my calipers, I will probably just be cleaning and installing the new seals with new pads/rotors for my project, but am interested in this none the less!

Good luck Andy can't wait to see your results!

[Andy911sc]

Fronts have been taken apart and prepped. Just have to finish the rears. I also made tick marks on the spacers and which caliper half they line up with. I will get a photo of that when I get a chance. I'm sure it's not that big of an issue, but I can be a little anal about things going back together they way they came apart exactly.

[dhagood]

so i have a silly question: at what point is it desirable to split the caliper halves?

[Andy911sc]

When you had a car sitting in one spot for 16 years. All the pistons were seized up, the brake fluid turned to sludge in the calipers, all the boots were torns, there was rust on the piston sides and there were pitted really bad. So, I decided to do a complete restoration of them.

[Andy911sc]

Bolts were rusted and to properly due the black oxide coating on them they would have to be removed. Plus proper plating of the calipers and I am glad I did. The square cut rubber rings to seal the halves were pretty hard and cracking. It would have been a matter of time with hydraulic pressure before they would have not functioned properly.