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Ted Mooney, P.E. RET
Pine Beach, NJ
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Cadmium plating disk brake rotors?
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Q. I would like to plate the brake rotors on my car after I have cross-drilled them. I am hoping someone could tell me what would be best (i.e., heat resistant, corrosion resistant, durability, etc.) for this project. I would like to plate the rotors on my own as I love to learn new and interesting things and I don't have much money to spend. Many aftermarket manufacturers use silver cadmium. Is this something a novice can do? I would also like to make the project as environmentally friendly as possible, would this pose a problem?
Any and all help would be greatly appreciated.
Thank you.
Eric Cieszkiewicz- Providence, Rhode Island
2001
A. Hi Eric. Cadmium probably can't practically be plated out of a non-cyanide solution. While I don't think anybody would have shipped you cyanide even before September 11 anyway, now it would quite possibly invite FBI scrutiny. So I think you'd have to forget the idea of plating your rotors yourself with cadmium. You might find a plating shop willing to plate rotors, or maybe not. Good luck.
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
A. Aren't the words "Cadmium", and "Environmentally friendly" mutually exclusive these days?
Marc Green
anodizer - Boise, Idaho
Please don't take offense, but ARE YOU NUTS?!
Why would you even attempt to do something that might degrade or destroy the braking efficiency of your very heavy fast-moving car? Plate the exhaust, plate the door handles, but for the sake of all the innocents on the road driving alongside of you, LEAVE THE BRAKES ALONE.
If you can't afford to have the rotors plated by someone who knows what they are doing and offers a guarantee, why are you doing something that could lose you your entire car, not to mention your life? We won't even go into the lawsuits that could leave you penniless, but I know for a fact that messing with the brakes yourself can let your insurance company blame you for ANY accident and not have to pay you a dime!
Please, please do not even attempt to do this.
Bob Zonis- Bohemia, New York
Multiple threads merged: please forgive chronology errors :-)
Q. I have a brand new set of disk brake rotors that are going on a show car I'm putting together. I believe they are currently just cast and machined steel with an oily rust preventative liquid applied.
I want to be able to find a plating or coating that I can put on these parts to allow day-to-day use and prevent any rusting on non-contact areas.
I've read that many specialty brake manufacturers cadmium plate their rotors (these are not) but I've also read here on finishing.com that just a straight cadmium plating could cause "cadmium embrittlement", which may not be good for a part such as this.
I would really appreciate any info or recommendations on this.
Best regards and TIA.
Chris Bonthron- Toronto, Ontario, Canada
2002
A. Cad plating doesn't sound right in this application as it is not very resistant to wear. Hydrogen embrittlement can occur if the hydrogen is not baked out after plating.
Jon Barrows, MSF, EHSSC
GOAD Company
Independence, Missouri
A. Thanks for your response Jon.
I don't think the wear aspect of the cad plating is really an issue for me. I really only require it to protect the "non-wear" surfaces from rusting. The "wear" surfaces should be kept fairly clean from the constant applications of the brake pads.
I suspect that the manufacturers that do cadmium plate of their rotors use it because it will easily wear off in the areas required but still stick to the areas where it's needed.
Chris Bonthron [returning]- Toronto, Ontario, Canada
A. I have the answer for you. Zinc plating, it looks as good as cadmium plating and is also cheaper. I own one of those companies that makes performance rotors and this is the finish of our choice.
Dave F [last name deleted for privacy by Editor]- Bolton, Ontario, Canada
2004
Multiple threads merged: please forgive chronology errors :-)
Plating the brake rotors for a show car
Q. I'm turning my vehicle into a show car and an occasional driver. The brake rotors can they be electroplated gold, silver and still be safely operated, and will it stop rotor corrosion. Is there a better way to go about this.
Thank you,
Devon Ritchy- Ft. Lauderdale, Florida
2002
Q. I also have the same question and notice you have no replies to yours. Have you found your answer elsewhere? Could you share your findings if you have?
Thanks, Bob
- Stevensville, Montana, USA
2006
A. Hi Robert. Sometimes the inquiries get a bit repetitive and people who have already responded to a similar inquiry don't respond again. So please be patient with the search engine; also, we've now combined several threads onto this one page to make it easier to see the response and perspectives.
The principal problem with gold plating rotors would probably be liability if the car got in a serious accident. Insurance companies may grab for escape clauses and might well give you a major problem if the car's brake components were modified by a D-I-Yer.
The other issues are that gold plating will wear off and you'll probably have to put it on thin for economy reasons. Finally, gold is a noble metal and can cause galvanic corrosion of the underlying steel -- zinc plating is sacrificial to steel and would be a better bet.
I don't know if they are commercially available or not, but I'd suggest looking for titanium nitride coated rotors. Titanium nitride looks almost like gold and is a very wear resistant coating.
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
Q. Thanks for the reply Ted-
I guess I wasn't really concerned about "Gold' plating for my show car but I want a look more like chrome. I have new rotors in the box from Baer which have been factory "washed" in zinc. They don't appear to be what I expected, there are small areas where you see surface rust already and they have a faint yellow color to them.
In Montana, I can only find 2 companies which will plate, and Nickel is the only real choice. Now, I hear nickel looks better but can it cover the zn washed rotors without a problem? I'm really a bit lost with all the possible combinations & processes in plating, especially the more I read on it.
Bob-
- Stevensville, Montana USA
2006
A. The most common platings for rotors seem to be cadmium, zinc, and zinc alloys (zinc-nickel for example). These are all sacrificial coatings, so I assume sacrificial metal platings are best for this environment. If that is true, then there aren't that many choices after all, because cadmium should be avoided for environmental reasons, and there are no other readily plateable sacrificial metals besides zinc and zinc alloys (aluminum is a possibility, but not readily electroplateable).
"Zinc washed" is a term that may be deliberately vague. I've never heard of zinc washed and assume they mean zinc plated. The parts should not be at all rusty. The yellow coloration is typical of a chromate conversion coating which is always used on top of cadmium, zinc, and zinc alloy platings.
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
Q. I called Baer, the manufacturer of my new drill/slotted rotors. They said their zinc wash and zinc plating are the same process. I do have some small areas of rust which I sent pics to the factory rep, he replied that it was normal and that there would be no further rusting, nothing to worry about at all.
Well, I know some people have had there rotors "electroless" nickel plated, I haven't seen them but they claim to look more like chrome compared to the zinc. My question is, can my zinc plated/washed rotors be nickel plated, any problem putting nickel over the zinc, can it be done?
- Stevensville, Montana, USA
2006
A. Electroless nickel is indeed shinier than zinc plating. If you look at any of the silvery-chrome color electrical contacts on cordless telephones, AC adaptors and the like, that is nickel or electroless nickel.
The zinc plating will be stripped away as part of the electroless nickel plating process (you will not be putting nickel over zinc) but it is no problem that the parts have zinc plating on them. Good luck.
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
Well, I feel I've reached a dead end. I have contacted several companies who do the specific plating I'm interested in, e.g., nickel, electroless nickel, zinc-nickel etc. -- but I cannot get through to talk with anyone to answer specific questions about the process. Basically, what you get via phone transfer is please leave a message & I'll call you back-they never call back; e-mail, same thing, no replies.
I feel dealing with such companies (limited in number that they are) they don't want to be bothered by such a trivial projects as mine (these are huge companies). Another big problem is "seeing" a sample of what the process would look like, no one offers photo galleries on their processes. I guess you must know what you want then speak to their sales staff and order, because they only sell what they do and offer no further discussion. One reply via phone was, "what do you mean what does it look like?" -- here, I'll transfer you, please leave a message!
For example, my most recent quest has been to see or ask what a zinc-nickel plating with a clear hexavalent chromate finish would look like and maybe an estimate. Well, I get stone walled to talk to anyone and no pics available, yet this is all they do. I just wanted to know if the finish looks shiny, chrome like, or dull & grey. I just can't find any photos of these finishes, & of course they must all vary according to their solutions. I think the electroplating industry needs some type of atlas. I guess I'm just venting.
- Stevensville, Montana, USA
Q. Hi, I am a college student fascinated by a lot of things, electroplating, and forming are among them. I am trying to find the best coating solution for brake rotors. My uncoated gray iron rotors, that I installed last year, rusted to the point of eating up half of my brake pads. I am getting new high-performance (and high bite) pads, and qualii-teee rotors, and calipers. This is for a run of the mill car, I just want high quality, long lasting parts, looks don't matter.
The way that I see it the only coatings that will help in this case (from the research that I have done) is:
Coat:
Cadmium
Zinc
"E-coat"
Passivation:
Hexavalent, or trivalent chrome passivation.
Molybdenate-phosphorus passivation
According to a manufacturer their gold-cad plating (hexavalent chrome passivation) will last 3x longer than plain zinc, They were referring to a salt-spray test though. This doesn't really help me, because salt spray is an entirely different mechanism for corrosion than high temperatures. Ideally, I want to go for a VERY thick zinc coating, followed up with the moly-phos passivation, and then maybe an e-coat. I think this will yield the best results, and still be environmentally friendly. The moly-phos idea comes from here:
http://www.p2pays.org/ref/33/32010.pdf
I am unclear about the passivation procedure, I don't want cad rotors, because I have had to handle the tires/suspension components A LOT in the past year. I don't want to work in the vicinity of cad, or hexavalent chrome dust, and get it on my hands. The cleanup procedure after working on this car is enough without being so very toxic. I have read that trivalent chrome passivation is better for high temps, and not nearly as toxic.
I ran some numbers, and if my car were going 90 miles an hour (its top speed, lol), then stopped, it would generate enough heat to warm the rotors to 600 °F (assuming it braked evenly, and no heat loss.) This is disregarding the rear brakes for good reasons, which I won't mention. Ideally, I want the coating to last 3 years, before the rotor sees enough structural damage to start harming the pads. I don't really care how pretty it is, though. So to summarize my basic questions (and thanks for listening):
1. Will a THICK zinc coat, with trivalent chrome passivation, about equal a cad coating for corrosion resistance?
2. Does passivation (over zinc, or cad) work a lot better than the base metal, or is not really noticeable?
3. Would a THICK zinc coat help deter corrosion at all, either with passivation, or without? I was thinking 30 mils max...dimensional tolerance isn't important.
4. Do you think a zinc/passivation coat (whether chrome, or moly) is worth the extra money for this?
5. Does "e-coating" help brake rotors noticeably?
I know this is a lot of different areas, but please post with whatever you know. AFAIK e-coating is electrodeposited paint, and grill paints does work for awhile...
Also, a friend of mine owns a plating shop that does zinc, among other things, so I won't be doing this work in my back yard. Although I suppose I could get a good cad coating from some spent Ni-cad cells ;) hmmmmm
Electrodeposition - Cleveland, Ohio, USA
2006
A. Cadmium plated rotors = terrorist plot to spew poisons along our national, state and local roadways. Cadmium plated rotors will go the way of leaded gasoline and asbestos brake materials once the EPA, environmentalists and class-action lawyers read this.
I doubt that any such coatings have been thoroughly tested for friction, wear and temperature -- SAE HS 24 Surface Vehicle Brake Systems Standards Manual. And since not vehicle manufacturer-compliant, using them may invalidate your auto insurance. Also, MIL-C-81562B mentions a maximum temperature of 450 °F for cadmium due to its volatility (zinc has a 700 °F. limit). Paint will trap heat.
If you wish to proceed, other threads recommended zinc plating. Use your old pads and drive on a private track until the coating is worn through in the pad contact areas, then install the new pads.
Good luck.
- Goleta, California
Finishing.com honored Ken for his countless carefully researched responses. He passed away May 14, 2015.Rest in peace, Ken. Thank you for your hard work which the finishing world, and we at finishing.com, continue to benefit from.
! Hello, Ken.
Thank you as usual for your insights and references! At first I thought, "Why is Ken being so aggressive towards a simple student-hobbyist question? The guy's only asking what is a good coating and why." Then I Googled "cadmium rotor" and appreciate your making this letter capture people's attention. It is indeed shocking that numerous companies are promoting cadmium plated rotors here in 2006.
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
Q. I didn't actually plan to coat these myself, and thank you for your witty response ;). I already read that letter, and a bunch of other ones. I don't see how that the zinc coating would help brake rotors since it usually doesn't even help room temperature steel survive the elements (being outdoors, for our foreign friends)
Is e-coating better?, or zinc with a trivalent chrome passivation?
I really want to build a letter that cannot only refute cadmium, but also hexavalent chromium for this purpose, while offering a genuinely better alternative. I am not knowledgable enough to provide this.
I did a lot of research on Electroless nickel plating, and the high phosphorus coating (11-13% phosphorus) seemed good, it does transform into Ni3P at around 400 °C.), which, from what I understand severely reduces the coating's corrosion protection by causing it to crack.
Ken, If by 'terrorist' you mean unregulated business, then I whole heartedly agree with you.
I can understand that cadmium is a horrible coating for this application, but I still don't know how it compares to other coatings that are available. If anyone has links to scientific literature on the subject, I would be more than happy to sift through it.
- Cleveland, Ohio
A. Hello, Michael. Actually there is very little difference in the corrosion resistance of zinc plating vs. cadmium plating (heavy zinc coatings applied by hot-dip galvanizing have lasted 75+ years) and what difference there is can be more than made good by employing a zinc alloy instead of straight zinc. Zinc-nickel plating or zinc-cobalt plating will probably prove superior to cadmium plating in corrosion resistance. I don't have the expertise to know what coatings might interfere with proper braking action though. If cadmium were stunningly superior to any alternative it would almost be understandable, but it probably isn't.
Ken is surely correct that widespread use of cadmium plating on rotors would result in a substantial amount of cadmium (a cumulative blood poison) accumulating and being washed down our streets and highways, which is a bad idea. Yes, we survived lead in gasoline, mercury in many products, and cadmium plating on hardware of all types, and we'd survive cadmium plated rotors. But I am shocked that these are available and wonder what government agency should be discouraging it.
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
Q. Hi Ted, Thank you for your replies. I am not concerned about the interference of the brake pads, because of reduced friction. As Ken said I can use the old pads to remove the plating from that area of the rotor, and I can also add a very fine abrasive if the coating has a high hardness to it, then clean the rotors, and install the new pads.
My biggest concern is finding the best coating for gray iron, in an occasionally high temperature environment. I don't think the rotors would ever get hotter than 800 °F.
I have to find something better than zinc, and from the additional research that I have done, any kind of chromium passivation seems to be a bad idea, because of the high temperatures involved. What is standardly used to protect steel/cast iron from high temperature use?
- Cleveland, Ohio, US
A. Sorry for the misunderstanding; I thought I answered: If I were you I would look into the possibility of zinc-cobalt or zinc nickel plating. Good luck.
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
You did, I was shooting for more of a discussion as to why the coatings you mentioned are better, or how much longer they might last.
Your replies are very helpful, and I will look into them. The friend of mine that owns the plating shop gave me a copy of the Metal Finishing Guidebook. I am going to attempt these coatings with the new rotors. Thanks,
- Cleveland, Ohio, USA
Multiple threads merged: please forgive chronology errors :-)
Q. I am looking for a substitute for cadmium that I can export in bulk. To be used as a coating on brake rotors.
Phil LowellOwner - Chicago, Illinois, USA
2007
A. Hi Phil. Cadmium and its alternatives are electroplated onto parts, so it's a rather involved multistep process rather than something you can put in a spray can and export. But I think you are right to want to get the cadmium out of the system.
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
Q. I have a '98 Cadillac Deville. I'm looking to replace all rotors. It's just for daily driving and NOT very aggressive driving. Which plating is better for this application, zinc or cadmium?
Brian johnsonauto repair - Lancaster Texas
January 22, 2009
A. Hi, Brian. Cadmium is a cumulative biotoxin much like Lead and Mercury. It's use is forbidden in many countries, and it should only be used where it's unique combination of properties is required.
Because rotors can be satisfactory without cadmium plating, they should not (in my opinion) be cadmium plated.
Regards,
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
A. Zinc is tested on average to last 100 hrs at 5% salinity. Our winter roads get 23% salinity, twice sea level, and thousands of hours. Hence why the bigger the zinc coated rotor, the more likely it fails after TWO winters. The math shows that our salinity would eat 1-2 mm per year, but x 0.25 due to only a few months exposure.
Cadmium? No CAD plated set ever failed, not after 100,000 kms (on a CIVIC!!), not after 5-6 winters. Not on the second car I tried.
Catch? CANNOT APPLY IT ON A ZINC COATED rotor.
CAD no brainer, but hard to find places to do it.
- Ottawa., Ontario, Canada
May 30, 2018
Thanks Chris. There are other catches too, such as: I don't think any OEM automotive manufacturer in the world has offered it for a long time; cadmium plated parts cannot be used in Europe; and they probably can't be used in Japan and some other countries either.
We've now combined a couple of other threads about Cadmium plated rotors into this discussion. Good luck.
Regards,
Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
Q. I know, hence why adopted strand woven carbon ceramic, the new technology that resolved classic CCB issues (e.g. poor cold performance), does not contract like metal, and lasts 2-3 times longer than classic CCB, some 300,000 urban spirited driving with occasional track days. These are only produced by four manufacturers, been only 3 years or so. Problematic was loosing 1,400$ rotor sets every two winters, that issue is resolved.
Chris Ralent [returning]- Ottawa, Ontario, Canada
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