Restoring Brake Calipers

[JRISER]

Is there any substance you can apply to calipers to preserve that just-bead-blasted-look and will stand up to the heat? Will bead blasting make them look like they were when they were new? Does anyone have any experience with this or restoring the engine fan and housing? I really do not want to powder coat anything.

BTW, I have already looked at the posts that outline painting and powder coating.

Thanks for everyone's continued help and encouragement!!!

[Early_S_Man]

John,

The original finish was cadmium plating on the cast iron, so ... no, bead blasting won't restore it, but it would be a good prep prior to getting them yellow zinc plated -- the current replacement finish that looks similar to the OEM cad plating.

[911pcars]

Painting calipers is an accepted practice among both porschefiles and ricers. Painting also avoids heat-induced plating that would normally cook the seals. Eastwood sells a yellow look-alike zinc-colored spray paint. That should mimic the look you want without having to disassemble and replate them. But I would mask the non-caliper parts (bleeder screws, through bolts, crossover pipe, mounting bolts and such, and of course rotor) to avoid the "if it doesn't move, paint it" military slogan. However, I don't know if the paint will hold up to the rigors of Porsche-type braking maneuvers.

Sherwood
http://members.rennlist.org/911pcars

[JRISER]

Thanks for the suggestions.

If the original finish was a cadnium plating, then wouldn't it be okay to plate them again with yellow zinc plating? I'm just curious as to why they would overheat.

[911pcars]

Don't get me wrong. You can replate the calipers. However, the process requires complete disassembly of the calipers. Something you may or may not want to do.

Sherwood

[911nut]

John, most people recommend not disassembling the calipers because they tend to leak when you re-assemble them and the seals that go between the spacers and the halves are hard to get.
I dis-assembled one of mine during the course of rebuilding this past winter and it didn't leak when I put it back together. I used the original seals in the re-assembly.
Maybe I got lucky

[Superman]

Ummm, I've been disassembling calipers and replacing seals for many years and no, they don't leak. Sure, if pistons are scored they can leak, but replacement pistons are available. There is no seal between the halves according to my understanding, but nobody takes them that far apart. At least I wouldn't. They probably would leak.

You'd have to protect the cylinder surfaces while they're bathed in the zinc stuff. Not sure how that would work. Painting is the most common. Laquer, I think.

[911nut]

Originally posted by Superman
Ummm, I've been disassembling calipers and replacing seals for many years and no, they don't leak. Sure, if pistons are scored they can leak, but replacement pistons are available. There is no seal between the halves according to my understanding, but nobody takes them that far apart. At least I wouldn't. They probably would leak.

Super, I'm talking about splitting the calipers halves.

[Early_S_Man]

The seals between the caliper halves are not O-rings ... they are just small versions of the Ate seal used in the caliper bore around the piston. They don't leak when replaced, unless the caliper was leaking beforehand due to massive internal corrosion from neglected brake fluid ... that is an urban legend of gigantic proportions!!! The factory sells the seals, as do VW and Mercedes dealers. The Clymer Porsche 912 Handbook has had the replacement procedure in it for over 30 years, now, using Porsche factory illustrations and pics. The biggest difficulty in splitting the caliper halves is that some use a very odd Ribe fastener that many assume is Torx, which it isn't ... and the bolt is destroyed by the Torx bit, rendering the caliper a piece of scrap!

[Superman]

Well I guess I don't know everything after all. I thought the caliper halves just fit perfectly together.

I've got a pair of Carrera calipers I've been meaning to refresh, so perhaps I will paint them. Or zinc coat. How are the cylinder surfaces protected during the zinc coating procedure?

[Early_S_Man]

Supe,

When I had some calipers replated with cadmium back in the '80s ... I didn't protect the bores, since they were originally cadmium-plated, too! No problems after the rebuild using the VW Type III caliper seals, either!

Here is an early parts diagram showing the split calipers, and the replacement caliper half seals, too ...

[JRISER]

Many thanks to everyone for the info. I am getting an education here that will help me make good solid decisions when restoring my calipers. Keep posting!