Calipers

[Bill Lawless]

HI 356ers, I had all my calipers yellow zinc plated about a year ago. Sat on the shelf because I'm wicked slow restoring my 65' C...
Anyway, I'm close to putting them on, pulled them out of the box, and they now show a lot of signs of RUST.. Or corrosion of some sort.. They offered to re-plate them...

Is there any kind of coating, high temp clear, or something that will stop this rust/corrosion I though the zinc plating was supposed to stop it from rusting..

Thanks much, as usual,
Bill

[Doug McDonnell]

Since they offered I would have them replate them. Should not have happened.

[Ron LaDow]

Bill, I'd say that originated under the plating. IOWs, they were not stripped properly. They SHOULD replate them and clean them properly this time.

[Jeffrey Leeds]

When you get them back put each one in a freezer rated zip-lock type bag until you are really ready to install them.

[Jules Dielen]

what are the black spots?

[Dick Weiss]

There are various caliper paint colors available from various automotive stores; That's what I use if needed.

Dick

[Bill Lawless]

Bill, I'd say that originated under the plating. IOWs, they were not stripped properly. They SHOULD replate them and clean them properly this time.

Thanks Ron,
That was my impression also. I asked them to be very careful with the cleaning... Hopefully!!!

[Bill Waite]

There are various caliper paint colors available from various automotive stores; That's what I use if needed. Dick

+1 Dick. I used a combination of VHT caliper gold, silver and clear to achieve a color more like the original plating. Misted on a light coat of silver immediately followed by a light coat of gold. At 10 minute intervals, did that a total of three times and then applied a heavier coat of VHT caliper clear. Photo is of the rear set in an Oster toaster oven after curing at 200F for 1 hour. Not sure how they will hold up versus plating, but they look pretty good now. Total cost was about $86, including a brand new Oster toaster oven I just bought (Walmart - if order online and pickup at store only $50, normally $99). Now I can "cook" parts in the garage (= happier wife). Not sure how they will hold up versus painting, but they look pretty good now.

[Dick Weiss]

Nice job, Bill.

[Emil Wojcik]

I used a method similar to bill's, using gold paint misted over silver. The misting is the key, making it look more like a thin plating than paint. I didn't clear coat mine, though.

I don't put a lot of miles on the car but when I do I often get the temps up on the brakes. The paint has held up fine over the past 14 years with this limited abuse.

I'm sure plated calipers would look more correct but when just looking through the wheel holes from a few feet away it looks very presentable.

[Bruce Hagopian]

The main point of plating is not for appearance, but, protection of the cylinder bores from corrosion.

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

[Bill Lawless]

There are various caliper paint colors available from various automotive stores; That's what I use if needed. Dick

+1 Dick. I used a combination of VHT caliper gold, silver and clear to achieve a color more like the original plating. Misted on a light coat of silver immediately followed by a light coat of gold. At 10 minute intervals, did that a total of three times and then applied a heavier coat of VHT caliper clear. Photo is of the rear set in an Oster toaster oven after curing at 200F for 1 hour. Not sure how they will hold up versus plating, but they look pretty good now. Total cost was about $86, including a brand new Oster toaster oven I just bought (Walmart - if order online and pickup at store only $50, normally $99). Now I can "cook" parts in the garage (= happier wife). Not sure how they will hold up versus painting, but they look pretty good now.

CALIPERS IN OVEN1.JPG

They look nice... Wonder if I can put a coat or 2 of that caliper clear right on the zinc plating to lock in the freshness. sort of speak!!!

Sent em' out I'll post what they look like when I get them back...

[WilliamVaughan]

Little pits form in rusty cast iron surfaces. The chemistry used to de-rust the calipers likely resides in small amounts in the residual rust in the pits. The chemistry re-emerges when it has the opportunity. My sympathy to the plater.

[Bill Waite]

The main point of plating is not for appearance, but, protection of the cylinder bores from corrosion.
http://www.pmbperformance.com/brakehowto.html

I have no doubt that plating does help prevent corrosion. But, I also used the same approach in 2004 when I rebuilt the front disc calipers on my '67 Sunbeam Tiger (no plating, just bead blasting and caliper paint). With brake fluid change every three years, the brakes have never missed a beat. The reason? I think it is primarily because of advances in brake fluid chemistry (anti-corrosion additives) and brake lines / hoses since the "old days." So, the zinc plating (though helpful) may be less required than in the past. Just a theory. Nevertheless, next time I rebuild any calipers, I'll have a serious look at plating. People more knowledgeable than me (= pretty much everybody) may want to add their opinions.

From an online article:

Traditionally, brake fluid problems occurred when moisture seeped into brake fluid, but the service issues with fluid today are different than 20-30 years ago. In fact, moisture in brake fluid today isn’t much of a service issue because modern construction techniques of flexible brake hoses have eliminated most brake fluid moisture intrusion issues.

Today, brake fluid can be accurately tested to determine replacement needs. This is because the most common issues stem from the levels of dissolved copper and depleted additive package in modern brake fluids. The level of dissolved copper in brake fluid is an indicator of the health of the brake fluid’s additive package. When the additive package of brake fluid is depleted one of the negative results may be internal brake system component corrosion and or sludge build up.

What is brake fluid corrosion?
Brake fluid itself doesn’t corrode but when the additive package, which is part of the brake fluid, is depleted or breaks down, the brake fluid no longer has adequate anticorrosive inhibitors so corrosion of internal brake hydraulic components may occur.

What is brake fluid additive package?
Brake fluid additive packages are additives that are blended into brake fluid stocks by manufacturers. Typically, a combination of anticorrosion inhibitors, anti-wear additives, anti-rust additives, acid neutralizing or pH balancer additives, anti-foaming additives and viscosity stabilizers are blended into brake fluids.

With usage of the vehicle the additive package blended into brake fluid when manufactured will not last forever. Depletion of additive packages is the main cause of brake fluid issues; resulting in the need for brake fluid service in vehicles.

[Bill Lawless]

Little pits form in rusty cast iron surfaces. The chemistry used to de-rust the calipers likely resides in small amounts in the residual rust in the pits. The chemistry re-emerges when it has the opportunity. My sympathy to the plater.

This could very well be true, but I've seen calipers done many years longer then these and still do not display this lever of rust after 10-11 mo. Even the plater agrees.