rmdsolutions

I am thinking of powder coating my 17 factory wheels anything I should know before I do this good or bad?

944Fest (aka Dan P)

I asked this question over in the racing forum, and got mostly negative replies about heat treating and hiding cracks. The painting procedure seems labor intensive and not as durable.
https://rennlist.com/forums/racing-and-drivers-education-forum/258354-track-rims-paint-or-powdercoat.html

Then again, maybe there is a difference between street and track rims.

SamGrant951

I did some research before powdercoating mine and decided I would not use the powdercoated wheels on the track/auto-x. Street is fine IMHO - Nothing beats the finish, they are amazing looking and brake dust just wipes away now.

Eyal 951

they look great, but the process weakens the metal. I'm sure street is fine as long as your roads are decent.

AndyK

How does powder coating weaken the metal?

IMB951

They use a ton of heat to cure the powder onto the metal, and it apparently upsets the rigidity of the molecules themselves.

AndyK

So does that mean my D90's that were powder coated by a local guy are useless?

Zero10

The heating when power coating can affect the temper of the metal. For this reason it is not advised to use powder coated wheels on the track. Also, it is possible for the powder coating to hide cracks, but I would suppose that the same is true for painted wheels.

Powdercoated D90's aren't useless, just don't run them on the track. They still look good!

AndyK

They'll be the prettiest snow tire rims ever!

bleucamaro

Wow, theres alot of fiction in this thread.

Aluminum anneals at about 650 deg. F. Powder cures between 350 and 375 deg. F. Softening ts not an issue. Conversely, to age harden aluminum (temper) it requires a heat soak at about 350 deg. F for approximately 8 hours (powder cures in 30-45 minutes). (source: http://www.suppliersonline.com/Resea...1&Mechanical=1 ) Seeing as how aluminum will naturally age to higher tempers over time at room temperatures, I don't think there is any additional hardening going on.

As for excessive heat, it takes a very modified oven to even get to 500 deg. F and costs a whole ton of money more to operate, not to mention it will ruin the coating.

When I worked at a powder coat shop, our cleaning process (more comprehensive than most shops) used a chemical stripper (similar to aircraft stripper) to remove paint, then blast with garnett or Al oxide, clean with solvent or a phosphate spray, or simple green, rinse, then dry in the oven / out-gas one hour at 250 deg. F, then clean again with solvent. As for other shops, subract a couple processes from that list.

Powder coating will hide any cracks in the wheels, but so will any other painting process. If you're really worried about them, strip them yourself, then have them dye penetrant inspected first.

I'm going to powder coat my D-90s an am not going to worry about them.

edit: my experiance is 5 years working in a powder coatings shop, and a BSMfg.E. If a materials engineer would chime in, we could all be set strait.

spedracer18

Finishing a BS in BME (emphasis biomaterials) with most courses in MatSci and engineering. Bleucamaro is exactly right. The aluminum alloy had been tempered, but you will not lose the tempering nor precipitation harden at a temperature of only 300-400 degrees for even 1 hour. It may be important to note that this may change depending upon the type of alloy the wheek is made of.

cjeckert

I think the bigger problem with powder coating is for racing purposes is that if it douse crack during a track session then it is alot harder to spot the defect and replace the wheel before it completly fails.

shmucklebuckle

Good to know, thanks

Zero10

Interesting, I was going by what I was told, but it's nice to have some expert opinions on this matter.
So, as long as the wheels are only left in the over for ~1 hour, there is no harm done? Cool.
I have a set of phone dials to powdercoat then

hacker-pschorr

I bought a set of used 928 GTS wheels from a fellow rennlister. They were refinished at one time (not by him) stripped and powder coated. When I received the wheels, I found a crack in 3 of the 4 wheels in the inside lip. These wheels were never used on the track; they were OEM on his GTS. He took the wheels back; only conclusion was the heating process caused the cracks.

Paint is cheap and easy, I wouldn’t take the chance with powder coating wheels.