RonCT

We had our CVR PCA meeting last night and the Northeast regional BBS representative gave a presentation. Of particular note was the damage that powder coating does to a wheel if it's done outside of the initial manufacturing process. In other words, if adding clear coat, anodizing, or even powder coating is factored in when the wheel is made such that the chemistry is planned out, then it's not a problem. But people that take delivery of a wheel and then send it out for powder coating are going to see a 30% degradation in the structural integrity of the wheel. The way I understood what he said - it was like heat treating something in the manufacture and then "undoing" it by baking on the powder coat. I didn't quite understand how that differs from heat cycling the wheel on the track - I just don't know much about the powder coating process.

Anyway - I had never before heard of negatives of powder coating metal and even wonder if this applies to things like roll bars. Just a heads-up to all...

P.S. He rolled his eyes and said "Honestly, I don't know why anyone wants black wheels in the first place - if it's to make the car look racy, it isn't working because all race cars have silver / aluminum colored wheels..."

jhbrennan

Not sure i understand all the science either, but I've been told many times that the heat used in the poweder coating process is the culprit - the guys at Wheel Enhancement confirmed this too.

blueillusion97

I'm just going to do a wild guess here...maybe because people have different taste at how their car should look and its not like his...But hey what do i know maybe all cars should look the same......But as far as heat damaging the wheel it could be true if powder coat is being heated at really high temperatures but i have no i idea what temperatures they use

texas911

Because black wheels look cool and they hide brake dust.

mxdave74

I'm no expert, but I believe powdercoat oven temps are between 190-230?... maybe someone in the biz will chime in.

Alstoy

Now you tell me!! I just got my wheels done. My only choice is to to compensate for the 30% degradation by slowing down another 30%. On a more serious note, has anyone had long-term experience with said wheels, or is their a resident physicist that could ponder the question.

MMD

Makes sense. Other than changing the alloy contents, heating and cooling (duration, rate, techniques) are the major way the characteristics of metals are manipulated. Casting or forging a wheel is a one-way "baking" process aimed at a specific result. Try reheating a cupcake and expecting it to be the same when it cools.

Try straightening a bent cast bronze deck cleat by (re)heating it; tap the heated tang with a hammer and it will snap off .

texas911

Does Porsche powder coat the OEM wheels? Or are they painted?

wdonovan

Did some searching and found a powder coat site with a FAQ that said normally 350F-400F. That's definitely hot enough to overage some aluminum alloys.

Alstoy, I'd opt for driving 30% faster and risking 30% less time on the road.

jhbrennan

Paint

bleucamaro

This does reach a temp to age the aluminum, but a 45 minute cure is not long enough. Most alloys take 5-8 hours to age at this temp.

Many OEM's powder coat their wheels, including BBS (http://www.bbs-usa.com/index.php?id=676), Mercedes, etc.

This topic has been covered here before, please read this: https://rennlist.com/forums/924-931-944-951-968-forum/262853-powder-coating-wheels.html

Coochas

Nice job. I agree!

Deanski

Oh damn, I missed the meeting!!!

As for powder coat temps, I would think the short duration would not make too much of an issue. I'd say just like heating them up at track events for that duration, but maybe not as high.

Besides, I would think that both OEM and aftermarket wheels would include a full disclaimer or other "warranty void" if powder coated.

Never heard of long term problems.

Deanski

Edgy01

Those temps for that duration can't possibly affect the metal's crystalization. Unfortunately, Porsche has moved to pressure cast wheels away from forged for the most part and they're inherantly less strong than the forged,--the forged having much larger crystal structures because of their cooling period. Powder coating possibly could weaken the aluminum wheels but suspect that is really something that would only be an issue for competition wheels,--not for street applications. I think this issue has come up just to cover someone's behind if abused.

P.S. Checked with some of my engineers and they can't figure out why, with those temperatures, it could be a problem.