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does powdercoating weaken wheels?

13K views 27 replies 18 participants last post by  avatar2140 
#1 ·
i heard this somewhere, dont think its true but i am extremely paranoid. i want to powdercoat my BBS wheels flat black since i hate cleaning them. it should look better on my rally red MR too.
 
#2 ·
I don't think anyone can give you a straight answer because it depends on the material of the wheel, whether it was heat treated and the powdercoat cure temperature.

Powdercoating uses enough heat to cause annealing of the metal. Wheels which are heat treated for added strength are affected more severely than wheels which are not heat treated. Wheels that are destined to be powdercoated are manufactured differently than those that will be painted. Unofficially, Tirerack recommends against powdercoating wheels.

The common argument here is that nobody has seen an outright failure of a wheel as a result of powdercoating. But consider if the transitional temperatures of powdercoating weaken the structure - one cannot see the effects, cannot feel the effects, and cannot test for these effects nondestructively. If pushed to the extremes, the wheel may not hold up. Now ask yourself if the typical end-user who powdercoats their wheels will push them to the limits on the street.

According to Materials Engineering forum, the common alloys used are 356-T6 for cast wheels and 6061-T6 for forged wheels. The common coatings are epoxy, polyester and acrylic powder coatings.

ASM Handbook:
356-T6: Aging at 305 to 315 °F for 2 to 5 hours
Yield stress = 185 MPa
Ultimate stress = 262 MPa
Fracture strain = 0.05

Based on this data, a 400 °F powdercoat treatment for less than 1 hour should not reduce the fatigue strength at a significant level, however to which extent the alloy is overaged and weakened is unknown. And nobody has the answer. Now that you are better informed, decide for yourself if you want to powdercoat or paint the wheels.
 
#3 ·
Yes it does, during the powder coating process the wheels basically go into an oven and metal when heated tends to get more brittle or weaker. I dont think anyone has tested the different types (cast, forged, semi-forged) before and after so I dont think anyone will tell you exactly how much weaker the wheels will be.
 
#4 ·
For all practical purposes no, its not going to weaken it enough to even call it weaker. The process for powder coating evenly brings the temp up then cools off slowly. So embrittlement won't be an issue either.
Really its about the same as brushing your teeth every day, or using whiteners.
 
#7 ·
got mine powdercoated, riding on swift springs, on the worst roads highways and streats in new york city--- went inside some potholes that i swore must have bent something... no problems---- your brakes heat the wheels up pretty good too after some hard driving ive been told, so i believe it should be safe...
 
#13 ·
yep, Im officially scared off powdercoating my bbs's
 
#14 ·
I was gonna bring up that most of us motorcycle enthusiasts PC our wheels... But then I realized that almost all bike wheels are cast.... dah well.
 
#18 ·
Well bummer. Was going to PC my BBS' :(
 
#20 ·
I really don't think that anyone will see problems with this unless you are pushing the wheels very hard, at least that's what I gathered from what FLK said. And by very hard, I mean that the car is a dedicated track car. I wouldn't think you'd see problems with the wheels if you are just a weekend warrior. This applies only to the BBS wheels.

GSR wheels shouldn't see any problems as they are not forged.
 
#23 ·
If you really want the flat color (matte).... and dont want to deal with the powdercoating. I more temporary approach might be using what I did with the Plasti-Dip spray. So far the wheels hold up (except to silly string) to normal wear and tear without any problems. The only thing I have found is that you cant scrub them clean or use a high pressure water/air source on them as it will peel the rubber off. A light pressure wash helps wash off some of the dust, but they still look great even if they are dirty. The more spray coats you put on, the more versitile it becomes.
 
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