Brake Caliper Powder Coating

[opelspyder]

I was looking to powder coat some calipers for the GT, but then relized about the seals in between the caliper halfs. I was worried about melting these. What temp would you all think they are rated at? Do you think they could withstand 300 degrees for a slight bit just to allow the coating to flow? I figure severe braking would get prttey hot and they would have to withstand that heat. Let me know what you think
Keith

[Phoenix]

This is somthing that I have thought about too. I know that they make specific paints designed for calipers though.

[opelspyder]

Okay I tried it anyways and from what I can tell it will be fine. What I did is I coated it, then baked it in 300 degree temp until the coating flashed/or set, then I pulled the part and dipped it in a cooling tank. Usually if something gets too hot it would be smoking, I think it was fine though. I will definitly test this before putting into hard use. I figure the seals have to be a higher heat rating just for extreme braking, and the halves are machined to tight clearances so if they did melt some, would it leak? I guess test will tell.
Keith

[BQS4]

Keith;
If you think you toasted the little o-rings, I can get you some for about 39 cents each.

[markandson]

I thought everyone has always said that you can't get those little square "O" rings that go between the caliper halves, or is that only for the '75 big brakes.

[jordan]

The special "square shouldered seal" are I believe around 3/4" in diameter and they are near, if not impossible to find in the correct dimensions and composition. DO NOT EVER use an o-ring for this job of any type, at this time I am almost certain that this component can not be sourced. 300ºf. should not hot enough to trash them, but I would definitely bench test them and replace the cylinder seal and dust boot along with the retainer.

[neuropel]

Gene Smith CAN get these O-rings. It's still not advisable to take them apart, but they CAN be replaced with the correct part. Gene's the only person I know of that's found them. Sounds like it doesn't matter at this point anyway, since the ones in this thread were successfully powdercoated.

As a side note, I recently blasted and painted my calipers with the new caliper paint that's out. That stuff goes on like no other rattle can paint I've ever used. If it holds up, I can't see a need to go to the trouble of powder coating unless you're wanting a custom color.

Todd

[RallyBob]

This may not be of any concern to those with street-driven Opels, but normal powder coating will actually burn off a caliper that is driven hard, whereas the special caliper paints actually hold up better. Yes, they get that hot under duress (I've measured brake pads at 1100* plus), hot enough under certain circumstances to melt the caliper piston seals....

Bob

[blancojp]

Howdy guys!
We powder coat calipers all of the time and the coating will last if done properly. The trick is to dissassemble the caliper, sandblast and only leave the metal parts to be coated. The O-rings are no big deal on all GT and Manta calipers since BMW, Volvo and Alfa (to name a few) use the same ones. But when in doubt, fing a hydraulic supply house and have them matched to what they have inhouse.

But if you are racing your vehicle, don't even bother to go through the exercise, you will waste your time and money.

[jordan]

Originally Posted by blancojp Howdy guys! We powder coat calipers all of the time and the coating will last if done properly. The trick is to dissassemble the caliper, sandblast and only leave the metal parts to be coated. The O-rings are no big deal on all GT and Manta calipers since BMW, Volvo and Alfa (to name a few) use the same ones. But when in doubt, fing a hydraulic supply house and have them matched to what they have inhouse. But if you are racing your vehicle, don't even bother to go through the exercise, you will waste your time and money.

If you do a little research into it you will find that it is not that simple. It's of an odd dimension for the required rubber composition.

[blancojp]

Jordan: Nothing is hard if you have taken the time to research it.
I have old catalogs which can be used to sort out the parts required. Remember, all I do is restore cars...

[RallyBob]

Originally Posted by jordan If you do a little research into it you will find that it is not that simple. It's of an odd dimension for the required rubber composition.

Jordan, not only is it an odd square-cut metric o-ring, it must be compatible with glycol-based brake fluids. You'll find that nearly nothing off-the-shelf is in fact compatible, except for EPDM. Most EPDM o-rings are only rated for a max of 350* too. Buna-N, Viton, nitrile, fluoro are all non-compatible! So unless you're sure you know what you are buying, it's a dangerous guessing game! Either buy o-rings made specifically for the ATE calipers, or buy them from a reputable o-ring manufacturer who knows the difference in what he sells.

Bob

[oldopelguy]

Originally Posted by RallyBob Jordan, not only is it an odd square-cut metric o-ring, it must be compatible with glycol-based brake fluids. You'll find that nearly nothing off-the-shelf is in fact compatible, except for EPDM. Most EPDM o-rings are only rated for a max of 350* too. Buna-N, Viton, nitrile, fluoro are all non-compatible!

Would this be a concern with DOT 5 (silicone based) brake fluid? As a general rule I prefer the pedal feel of DOT 4 or DOT 5.1 glycol fluids, but if it meant the differance between a set of junk calipers with no seals and a set I could use with $3 seals, I might be willing to do that swap. Sure purging the rest of the system and replacing cups on the wheel cylinders and master cylinder is a pain, but those parts are still reasonable availalbe, and also cheap.

[opelspyder]

I personally do not like silicone based brake fluid, It seems to cuase problems with components after long use. I think on this next one I am going synthetic brake fluid. Then I don't worry about paint removal and such, some may say pedal feel is not as desirable.
Keith

[jtb]

Originally Posted by opelspyder I personally do not like silicone based brake fluid, It seems to cuase problems with components after long use. I think on this next one I am going synthetic brake fluid. Then I don't worry about paint removal and such, some may say pedal feel is not as desirable. Keith

What kind of problems with long term use??? I've run SBF for years in various cars with no problems.
Also, I'm pretty sure SBF does not harm paint (though I've never poured it on a fender to check!)

jtb