Heat Curing powder coated wheels, Stress cracks / Material strength concerns.. Options

[yarin]

A thread on the main board sparked a bit of curiosity regarding my plan of powder coating my Panasports this winter. I figured you race guys might have experience here. Wheels are Panasport (UL) Ultralights, aluminum with steel inserts for lug seats. The curing process consists of baking in an electric oven at 375F for 20-25 minutes. I obviously wouldn't want to compromise the integrity of the wheel. Would the steel/aluminium combo cause an issue when curing the powdercoat? Any thoughts on this? I've heard theories that heat treatments have led to wheel failures on the track due to stress cracks.

Also - I assume I should avoid powder coating the seating. what about the valve stem seat? I would imagine i don't want to touch the seating surface to the hub. right? Also what about the tire seat lip?

Here are specs on panasports:

*New, virgin aluminum alloy materials used throughout.
*Hub centric machining for every application, no universal sleeves
*Steel, tapered-face inserted lug holes for secure fixing and self-centering attachment
*Heat treated for high strength and durability
*The proper balance of designed material location providing a light weight wheel with intense strength

Any advice would be helpful. Thanks!

[Mugs914]

Just my .02, but I never liked the idea of powder coating wheels, especially if they will be used on the track, because the thick powder coat can hide cracks. Whether they come from the baking process or from banging over the rumble strips you want to be able to see any cracks that form sooner rather than later. Come to think of it, there aren't too many things that I powder coat on a race car, maybe the engine tin... (IMG:style_emoticons/default/biggrin.gif)

Of course street cars that see the occasional track day don't take the regular abuse that track cars do so powder coating is fine for suspension bits or whatever, but I still wouldn't mess with wheels unless they are for the street only. As for your Panasports, if you have any question at all about the heating affecting their integrity don't subject them to the process.

It may sound funny, but I use Krylon for things like wheels and suspension pieces. Clean whatever it is really well then just shoot it whatever color you like, no primer or anything. It looks good, its easy to spot damage, touch-ups are easy and it holds up a lot better than you think!

Besides that, its cheap... (IMG:style_emoticons/default/beerchug.gif)

As I said, just my zwei pfennig...

[Joe Ricard]

I agree with Mike. Do not powder coat your wheels as you will not see any stress cracks till it's too late.

I paint my steel wheels every year after I strip them. I polish my Aluminum centerlines before most every event which gets me to inspect as I go.

[i love porsche]

as far as stressing the wheels from the baking process..i dont think the temperatures are high enough to cause any real change or hardening in the aluminum.

but i agree on the no powdercoat on the wheels...they do hide cracks and a good paint job will look just as good or better

[street legal go-kart]

Most good powder coaters will not touch alloy wheels.
There are a variety of things that can happen, both in the prep phase and in the curing process.

For the same reasons they will not touch alloy suspension bits ect...

Call Caps Powder Coating in Fresno , Ca. for further explanation.
These guys do bits for the race boat and will tell us when we are about to vertically fornicate something.

And I agree with the 2cts that Krylon works just fine for most applications..

JT

[powdercoater]

Here is the scoop. All of you have some valid points and a few skewed ones. Powder coating applied to an aluminum wheel is a practice that is used by wheel manufacturer’s world wide. This includes such performance wheel manufacturers as OZ and Gemballa. There are areas to be aware of. Most powder coatings are cured in the 375-400F range. While these temperatures are not normally associated with annealing or heat treating changes they are starting to get close. Some powder coaters do not understand that their ovens have areas that are hotter than others. If wheels are not given the proper attention and the oven operator is not doing their job, the wheels could see temperatures approaching 500F. Temperatures in this range can be worrisome if the wheels spend extended times in that environment. This can happen and I have personal experience with this happening to another powder coater’s client. The wheels where dead soft and would not be acceptable for any application. Cracks are a different subject. It is true that powder coating can hide some small stress cracks. This is the reason that Top Fuel funny cars and dragsters do not coat the frames; they are usually kept bare with a coat of WD-40 except a spray can job to the top roll cage hoop just for appearance sake. These are also vehicles that exhibit great deals of wheel shake and abnormal vibration input that most vehicles will never replicate even in racing form. If you have stress cracks in your club racing wheel you probably hit something hard and you should have the wheel stripped and magnafluxed or x-rayed to confirm any potential damage. But really, how many of you have ever cracked a wheel from standard racing? Not many as this a very rare incident. Stress cracks are not a real reason not to powder coat a wheel. Especially when the guys that build racing wheels do it on their products. This is not a well founded belief. I have personal experience with powder coating all forms of racing wheels and with the exception of Trophy trucks and vehicles of this nature the concern of damaging a wheel by powder coating has no basis in the real world. This also applys to all other aluminum products including suspension componentry. The unfounded tales of aluminum parts not being able to be coated are not true. Remember to choose your powder coating company just like any other service. Go to someone that has the experience and does not pass along mis-stated un-truths that are not based on actual experience or science. With very few exceptions most any metal can be powder coated without damaging it. One area of special concern is high pressure cylinders like scuba and gas cylinders. If these are not done correctly Hydrogen embrittlement will occur and high pressures will cause the vessel to fail and that usually means it will explode. Ther are maximum temperatures and dwell times for these items and they must be followed comprehensively. Hopefully this helps with some of your questions.

[Eric_Shea]

Excellent! (IMG:style_emoticons/default/smilie_pokal.gif)

(IMG:style_emoticons/default/welcome.png)

[McMark]

Awesome! Thanks for sharing some real world knowledge.

[J P Stein]

Ya'll do what ya want, but I strip my race wheels down to bare metal, grind a .05 minimum radius on all edges then repaint them myself......that way I have nobody but myself responsible for them.....I'd have em' shot peened iff'n I could find someone I trusted to do the job. Fuckabunch of pretty.