Ive got a local shop that will powder coat at a decent rate. Could I have my 12" rotors powdercoated or will the heat make it come off. If so, what would be best? Would it be a bad idea to not waste time masking, and just have the whole thing done, then drive REAL carefuly on back roads with aggressive braking and what not to just let the pads wear the coating off the braking area?

I would say you could do the whole thing and then take the rotors to a brake shop and have them machine the powder coating off the surface where the pads contact.

I don't think this will work though as powder coating is applied as a powder and heated so it melts.

I don't think the heat is much over 500 degrees max, I seem to recall the home powder coating setups are in the 350 degree range.

Heavy braking will create higher heat than 350 degrees so I would think the powder coat would re-melt and spin off in some areas.

Just my powder coating ignorant .02 worth.

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Where will the road take you today?

Some helpful links I've done
How to remove inner door panels, with pics.
How to remove outer door panels, with pics.
How to make rear coil-overs using factory struts, with pics.

quote Originally posted by 86GT3.4DOHC: Would it be a bad idea to not waste time masking, and just have the whole thing done, then drive REAL carefuly on back roads with aggressive braking and what not to just let the pads wear the coating off the braking area?

Do DOT do this! It will not wear off, but will melt into the brake linings. You will be replacing the pads if you do it.

Conventional powder coating will NOT hold up to the heat of a brake rotor. You can get them done in high heat powder though, it should hold up unless you are driving stupid. Have the rotor coated and then have them turned, you will be best off that way. The alternative is to have the shop mask off the braking area and then do the coating.

It will wear off or scratch.Also if you need to have the rotars turned,like most people do,every so often.It's going to come right off at the brake shop.

Don't powder coat them. Even if the coating doesn't melt and make a mess, it will act like a blanket and slow down cooling of the rotors. This is not a good thing. I tend to agree that most of the coating will end up all over your brake pads and wheels fairly soon after you try it.

If you want them to look nice and still cool properly have them coated with one of the ceramic products. www.techlinecoatings.com and others have coatings that are suposed to improove heat elimination.

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The only thing George Orwell got wrong was the year...

The Ogre's Fiero Cave (It's also at the top of every forum page...)

This brings up an interesting thought.

As an overall performance increasing measure, I would think you would wish to black ceramic coat those things that you wish to dissipate heat quickly (brake rotors), and "aluminum" or "chrome" ceramic coat those things you wish to retain heat. Thermodynamic emissivity being the parameter being optimized.

I pose the question then, in a turbocharged application, would you wish the exhaust piping into the turbocharger to be "chrome" ceramic, and the pressurized intake into the engine to be black ceramic coated??

edit: "emissivity" spelling

[This message has been edited by zardoz (edited 04-10-2005).]

i painted mine, and it is holding up great, i just used hight temp paint,
or if you want to do clear to prevent rus, just get them Zinc Coated

i painted my whole roter, then just drove carefully and let the pad wear off where it rubs it looks great, and i didnt driv on a buisy street

Zardoz

The color isn't always as significant as the type of product. A black coating could be an insulator or a promoter depending on how it is made. For a brake rotor you'd want a heat disipatoin promotor.

For a turbo, Yes, you could probably use an insulator on the exhaust side and a disipator on the intake side. Hard to say how much it would help. Should at least help the trubo look nicer.

Others

Galvanizing does make the rotor look nice. I'm not sure if it helps or hurts thermally. I would guess it doesn't hurt as much as the rust blanket that builds up on rotors, especially inside vented rotors.

Ogre:

Thanks. More research for zardoz.

In my business (aluminum alloy casting, both high and low pressure), I am constantly tinkering with thermodynamic tweaks to get more performance out of a given system. I'm in the middle of stepping on our metallurgists' toes now, questioning levels of oxide impurities in the alloy for a given project.

I have mentioned this before, but we do primarily automotive work. Our Tooling Manager helped design the dies for the '88 Fiero brake calipers in another life, and then produced them. I would tell you more, but they would shoot both you and me.

Seems to me that any coating creates a refraction boundry which in turn will inhibit heat flow.

JazzMan

I don't know anything about the powder coating. I would assume that if it was capable of handling the temps then it would be OK. But I would NOT get any on the actual rotor area, just do the hub areas. But that would be true of most any coating except maybe zinc oxide.

On the issue of Ceramic coating, I thought that ceramic coating was an insulator, period. I didn't know that some were promoters and some inhibitors. They ceramic coat exhaust and advertise the fact that under hood temps are lower do to less heat being transfered from the exhaust pipe. They also advertise its benefit to turbos due to higher sustained exhaust temps. I would think that ceramic would not be good for a part that needs to loose heat.

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RickN
White 88GT 5spd
White 85GT Auto

Oh so you don't say?

and chromed too. Girl not included, sorry.

[This message has been edited by madcurl (edited 04-10-2005).]

So far, in my searches, I have found this website. They claim their products are used by top fuel dragsters. Both thermal barrier and dispersant coatings. It describes their use on both brakes and intake manifolds. Also use on clutches and intercoolers. I would like to find a little more hard data on btu/in^2/sec or cal/cm^2/sec improvement over bare metal.

http://www.thinair-usa.com/Ceramic.html

I found some other information on space satellite applications, and they go into absorption/emissivity ratios of certain titanium based black coatings. However, not in the realm of practical products for the automotive hobbyist.

Zardoz... If you read that site and Techline... a good chunk of their stuff is infor right off the Techline site. They don't even bother to change the product names. If they aren't a Techline applicator I'd be fairly surprised.

Techline has some products that they sell to the public and others they only sell to application shops. Part of the reason is that some of their coatings are more dangerous than others and they don't want to deal with all the stupid people that would probably kill themselves.

I painted mine with spray can on the vette and its held up for over a year. I masked off the braking surface, so all I painted was the outter finned rim and the center hub.

Chrysler powdercoated my Magnums rotors from the factory with silver, then machined the braking surface. They look brand new after driving all last summer and this winter.

Ogre:

Thanks for the cross-reference.

I read the MSDS on the TLTD thermal dispersant, and it looked fairly safe to use. Mainly MEK and ethanol as carrier solvents. I was thinking that iso-cyanates might be in the mix when you warned about the hazardous materials. On the MSDS it refers to the TLTD as a dry-film lubricant (molybdenum disulfide...makes sense), but on the reference page, it calls it a thermal dispersant.

The HHTD looked safe within reason too. Xylene and iso-B alcohol as carriers.

I painted a car (69 Camaro), 25 years ago with Imron two-part, and I had the proper equipment to do it (still here and kicking). Now days, I would guess that a private individual could not buy Imron or its equivalent anymore.

quote Originally posted by zardoz: I pose the question then, in a turbocharged application, would you wish the exhaust piping into the turbocharger to be "chrome" ceramic, and the pressurized intake into the engine to be black ceramic coated??

Interesting idea. My answer is "it depends."

If the engine compartment temperature is hotter than the pressurized air temperature then making the pressurized tubes black would actually help them absorb heat.

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Doug Chase
Chase Race
Custom roll cage and exhaust fabrication