What do you think about Cadmium plating?
 

I've just ordered some crossdrilled rotors and am thinking about Cad plating them to keep the hats and non contact areas from rusting. Any opinions on the process, or how they affect rotors or braking? Any recommendations for plating companies in the SF Bay Area who do a good job and what they charge?

Cast iron - which rotors are typically made from - is a difficult material to plate. The cast iron microstructure includes free graphite, which provides a poor surface for plating adhesion.

Plus, good luck finding shops that can cadmium plate for you.... especially in California! Cadmium (like lead) is considered a heavy metal and the EPA is providing plenty of disincentive for shops to plate cadmium.

What about using high-temperature paint... similar to what's used on engine blocks?

Good points about the cadmium plating process...

Unfortunately, most off-the-shelf engine paint products wouldn't withstand the heating/cooling cycle of discs.

Ever watch those TV race-cams that they mount behind the one of the wheels of a race car? You can see the discs glow bright red every time the driver brakes, and immediately dissipate once the pedal is released and air is flowing again!

That's torture for any product not molecularly bonded to the disc!!!

G-Benz, you're right about thermal cycling being tough on paint. But I have had some luck in painting brake components. Whenever I do a brake job on one of my cars, I gritblast and paint the exposed nonworking metal surfaces of the caliper and rotor, simply using Rustoleum primer and paint. I just have this "thing" about exposed metal on my car. Surprisingly, the surfaces seem to hold up well over the years. For dave it may be worth a try.

Are those electrons organic? :p

..... and compostable!!

If rotors are difficult to Cad plate, I'm curious as to why so many companies offer it on their rotors. Another way to add $$$?

I've located a couple of places locally that will plate rotors for me. Just not sure what all the pluses and minuses are. I had someone recently tell me Cad plating causes pulsating during braking due to uneven surfaces. Is that a legitimate concern as well?

Oh and whats grit blasting?

On these rotors that are offered with cad plate.... are they cast iron rotors or steel rotors? If you CAN get it, it's a superior plate... very corrosion-resistant. The original Ford Model T's used it on fasteners. And they also use it on naval aircraft. You wouldn't want the plate on the working surfaces. I don't know how the plating process would result in brake pulsation, unless the working surfaces were plated.

Grit blasting is a wider term for sand blasting.

All of the rotors I've seen that are cad plated are plated over the entire surface. I assume they're steel but I'm not positive.

http://www.myroadster.net/images/t_rotors.jpg

Painting the rotor hats and other surfaces can be done with excellent results using high temp exhaust manifold paint. These paints are designed to withstand 1200 degrees. I use the same (except its 500 degree paint) for painting calipers, never had a problem and I race my 190!

Don't forget that there are special paints (only black) that can be used on bar-b-ques too. I've used these paints on the exhast on air cooled engines with godd results. Just my .02

Cadmium melts at 610°F. I don't see how it could function on the working surface. I looked at the attachment. Are you sure these rotors are for street use and not show?

I can't help but get the feeling that I'm missing something, because these rotors are apparently manufactured and okayed for use on vehicles.

As a bit of useless trivia, at one time the nuts on US Navy warship nuclear reactors were Cadmium plated. Admiral Rickover liked how it made them shine. Unfortunately, the radiation interacted with the Cadmium and steel of the nuts to embrittle it. Fortunately, this was discovered before any failed catostrophically in service and caused the reactor vessel head to come off!

Probably not a concern for Mercedes brakes, I admit.

My understanding is that eventually the Cad wears away from the rotor surface. Stays nice looking on the rest of the rotor (ie. hat and non contact surfaces)

The rotors in the link are street rotors and there are several sites that offer Cadmium plated cross drilled or slotted rotors as a performance upgrade to OEM rotors. Definitely marketed as a performance rotor.

Guess I'll have to remove the nuclear reactor aftermarket kit I have on the CLK if I decide to go with the Cad rotors!

;) ;)

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