Powdercoating control arms?

We've talked abit about PC'ing wheels and the affects on heat treating..........any such concerns for control arms?

I'm getting ready to start teardown on the Miata, and since I'm basically replacing EVERYTHING but the control arms, I thought I'd go ahead and have them cleaned up and powdercoated.

This will be used with R-comps and on the track.

Should I just stick with paint instead?

I powdered coated the upper arms on my 1972 Camaro years ago... That was good money wasted.. lol Since it wasn't a show car, paint would have been just as good... But they sure were pretty...

I'm not a metallurgist, but...

Miata control arms are steel, whereas most wheels are aluminum. Given the difference in melting points, I'd be surprised if the heat treat/temper threshold temperatures were the same. Lots of strength-important steel things are powder coated, most of the Miata roll bars on the market for example.

--Ian

My reason why I'd rather paint the control arms is simple - if/when the powercoating gets damaged, you can't just touch it up and you have an ingress point for water. I personally don't like that idea, call it "used to live in the UK paranoia".

^I have a DD, I can't imagine this ever being driven in wet weather!

codrus wrote: I'm not a metallurgist, but... Miata control arms are steel, whereas most wheels are aluminum. Given the difference in melting points, I'd be surprised if the heat treat/temper threshold temperatures were the same. Lots of strength-important steel things are powder coated, most of the Miata roll bars on the market for example. --Ian

Good point, thanks for the reality check.

codrus wrote: I'm not a metallurgist, but... Miata control arms are steel, whereas most wheels are aluminum. Given the difference in melting points, I'd be surprised if the heat treat/temper threshold temperatures were the same. Lots of strength-important steel things are powder coated, most of the Miata roll bars on the market for example. --Ian

This!

(Graduated with my degree in MatSci/Engineering last year)

Expanded answer, for most steels you need to get over ~500c to do much of anything to it. You're only heating up to about 200c for powdercoating. That said, this is from memory, not looking at my books.

Anything below 400F with an air cool shouldn't do anything appreciable to the sort of steel used in automotive control arms.

Plus its not just temperature, but time at temperature. 1 hour per inch of thickness soak time is a good rule of thumb. If you bring it up to temp, soak it for 10 minutes curing temp, and air cool, you are not even heating any part under 3/16" thick all the way through. If you just put it in the oven for 10 minutes and pull it out with no soak time, even less to worry about.

BoxheadTim wrote: My reason why I'd rather paint the control arms is simple - if/when the powercoating gets damaged, you can't just touch it up and you have an ingress point for water. I personally don't like that idea, call it "used to live in the UK paranoia".

Well.. sorta...

You can touch it up.. You just can't apply a spot of powder. You have to use paint.

You can paint over powder. It just may not match very well...

I have road raced a MKI MR2 where first I painted the suspension with epoxy and it did not hold up. It got chipped and the heat from the brakes and even the shocks discolored it. True this is a racing application, but the same suspension powder coated held up much better and it was not any high temp powder either.

This MKI MR2 shot shows a corner with an "aged" epoxy painted strut and a "used" powdercoated hub/knuckle. They started out the same silver/aluminum color.

http://carpron.com/multisite/v/Upload/PDoane/HTsFrontbarlinks1.JPG.html?g2_navId=x5de927b4

A fresh MKI MR2 corner with all powdercoat

http://carpron.com/multisite/v/Upload/PDoane/PCoat18a.JPG.html?g2_navId=x5de927b4

I have also powder coated a street MKII MR2's suspension. Without the rulebook to limit me, I actually took the time to grind off all the casting seams and the rough pebble finish.

http://carpron.com/multisite/v/Upload/PDoane/Fswaybar1.jpg.html?g2_navId=x5de927b4

http://carpron.com/multisite/v/Upload/PDoane/Rswaybar1.jpg.html?g2_navId=x5de927b4

and a racing MKII MR2 suspension where I only removed/ground off the casting seams

http://carpron.com/multisite/v/Upload/PDoane/IMGA0022_2.JPG.html?g2_navId=x5de927b4

http://carpron.com/multisite/v/Upload/PDoane/IMGA0023_2.JPG.html?g2_navId=x5de927b4

http://carpron.com/multisite/v/Upload/PDoane/IMGA0004+5.jpg.html?g2_navId=x5de927b4

http://carpron.com/multisite/v/Upload/PDoane/IMGA0001+6.jpg.html?g2_navId=x5de927b4

I would never go back to epoxy for the suspension pieces. I still use epoxy for the wheel wells and floorpans, but have been thinking about the self leveling brush on stuff (can't remember the name) that is very easy to apply and very tough.

BoxheadTim wrote: My reason why I'd rather paint the control arms is simple - if/when the powercoating gets damaged, you can't just touch it up and you have an ingress point for water. I personally don't like that idea, call it "used to live in the UK paranoia".

This. Just use paint. Hammerite is costly but it's tough and easy to touch-up. Contains anti-rust chemicals too.

GameboyRMH wrote:

BoxheadTim wrote: My reason why I'd rather paint the control arms is simple - if/when the powercoating gets damaged, you can't just touch it up and you have an ingress point for water. I personally don't like that idea, call it "used to live in the UK paranoia".

This. Just use paint. Hammerite is costly but it's tough and easy to touch-up. Contains anti-rust chemicals too.

Powdercoating is also much easier.

"Here take this, clean it and powdercoat it hot pink. Call me when its done"