Magnesium refinishing (bellhousing, wheels, etc)

[Unbalanced Engineering]

Hey guys,

The RF99 I purchased a few months back has what looks like the start of corrosion on the bellhousing. And since the car is apart, I'd like to fix it now. But it appears that the older methods all no longer apply since the chemicals are unobtainable. I've searched the internet and ApexSpeed without any luck. So please keep your responses applicable to the processes or professionals we can use today (ie no comments about chromate, DP90, etc).

Does anyone have experience with PreKote? If so, which primer and paint did you use?

Any other processes that work well?

Any professionals I could send it to?

Thanks a lot!
Jason

[pooch776]

Besides DOW-9, I have successfully used PPG DP90 epoxy primer (flat black) and Kephos coating (semi-gloss black) applied by KECO Coatings located in Indianapolis. I have never used powder coating on mag parts but I would think that may be another option.

Cheers, Joe

[kea]

Gary Arentz,
San Andreas, CA
209-754-4496

[Unbalanced Engineering]

Besides DOW-9, I have successfully used PPG DP90 epoxy primer (flat black) and Kephos coating (semi-gloss black) applied by KECO Coatings located in Indianapolis. I have never used powder coating on mag parts but I would think that may be another option.

Cheers, Joe

My understanding is the the DP90 is among the products that is discontinued....

[Unbalanced Engineering]

Gary Arentz,
San Andreas, CA
209-754-4496

Thanks, can you share a bit about your experience with Gary? Company or email contact info?

Thanks!
Jason

[Robert J. Alder]

Am I missing something here? KISS, as they say. For years I've simply painted Mag uprights and/or Hewland Mag VW tranny cases with rattle can high-temp gloss engine black. Holds up just fine assuming you first clean thoroughly and maybe use a good rattle can metal primer first.

[Unbalanced Engineering]

If you don't go down to bare metal, I think your approach works well. But when you need to go down to bare metal to remove corrosion, I think it gets more complicated to ensure that the primer sticks and the corrosion doesn't return.

If it was a wheel or upright, I'd be less concerned about having to redo it in a few months, but with the bellhousing, it requires pretty much disassembling the back half of the car to get it out....

Thanks,
Jason

Am I missing something here? KISS, as they say. For years I've simply painted Mag uprights and/or Hewland Mag VW tranny cases with rattle can high-temp gloss engine black. Holds up just fine assuming you first clean thoroughly and maybe use a good rattle can metal primer first.

[SEComposites]

Gary Arentz,
San Andreas, CA
209-754-4496

Gary has done a few mag cases for me and they always look great.

[hdsporty1988]

Years ago I read in one of Carroll Smith's books that you just need to periodically rub a little WD40 on magnesium to avoid corrosion, so that's what I do. Here's a link to the page in "Engineer to Win".

https://books.google.com/books?id=S0...nesium&f=false

[kea]

Gary has done a number of Mag casting for me and my customers over the years.
Very happy with the quality.

[Unbalanced Engineering]

Thanks for the recommendation.

And yes, the WD40 displaces the water that can cause corrosion. So sound advice.

Thanks,
Jason

[stownsen914]

My GT racer has mag uprights and a mag Hewland. I periodically wipe them down with a mixture of 50% motor oil cut with 50% mineral spirits. Same idea as WD40, per Mr. Smith.

[Charles Warner]

Thanks for the recommendation.

And yes, the WD40 displaces the water that can cause corrosion. So sound advice.

Thanks,
Jason

WD40 alone will evaporate too quickly. As has been suggested, mix it 50-50 with motor oil. That's what we use when shipping a car across the water on a ship. Works perfectly.

[Tuiguy]

WD40 alone will evaporate too quickly. As has been suggested, mix it 50-50 with motor oil. That's what we use when shipping a car across the water on a ship. Works perfectly.

Spraying the housings and wheels with Gibbs Brand (sprays on like WD40 but lasts longer) has worked well for me.

[Unbalanced Engineering]

I just got the Bellhousing back from Gary. Looks great, wasn't cheap ($335) since it has a lot of surfaces, will be spraying with Gibbs to keep it as fresh as possible. Thanks again for the suggestion and I too would highly recommend using Gary for Magnesium Chromate coating.

Jason

[Rick Iverson]

Is it the DOW-9 process?

V/r

Iverson

[Raleigh]

https://www.aviall.com/aviallstorefront/p/598970=6P

“Magnesium Aero”, It should be easy to obtain State side.

[Unbalanced Engineering]

BTW, not sure if this is the same coating as he used to do, but this coating is VERY fragile. Just handling it is enough to rub it off... Not really that happy with it at this point....

[billtebbutt]

I found high zinc content paint made by VHT. Sort of looks like cast iron, called "NU CAST" . Held up really well on mag castings on my old March. I was very happy with it

cheers
bt

[Raleigh]

I have been using the tempo range of zinc coatings on Mag with no ill effects for many years.

https://www.aviall.com/medias/2356.p...ttachment=true

[Jed348]

Gary Arentz,
San Andreas, CA
209-754-4496

He does the best job, reasonable, excellent quality.

[jkeller]

Mike Barnby at MB in England racing wheels has this on his website

http://www.mb-racingwheels.com/magnesium_protection.htm

[macbt21]

Hey guys,

The RF99 I purchased a few months back has what looks like the start of corrosion on the bellhousing. And since the car is apart, I'd like to fix it now. But it appears that the older methods all no longer apply since the chemicals are unobtainable. I've searched the internet and ApexSpeed without any luck. So please keep your responses applicable to the processes or professionals we can use today (ie no comments about chromate, DP90, etc).

Does anyone have experience with PreKote? If so, which primer and paint did you use?

Any other processes that work well?

Any professionals I could send it to?

Thanks a lot!
Jason

I have had some old Brabham Magnesium wheels treated with DOW #7 at PTI Industries in Enfield, CT. The quality of their work seems to be very good because their primary customers are in the aerospace industries and military. When done, they carefully pack each wheel individually in heavy plastic bags and add several desiccant packages to protect from moisture. They also provide you with a ISO certificate of quality. Before I took them to PTI I had them glass bead blasted with virgin media with only enough pressure to get the job done. You need to be very careful to not contaminate the magnesium during and after glass beading. Wear gloves at all times. Make sure the magnesium part is bagged right after cleaning and don't expose to air. It starts corroding almost immediately. Magnesium treated with DOW #7 should ideally be painted as soon as possible. Paint adheres to DOW #7 very good.

[DanW]

Someone wrote about this years ago and I was able to find it at Aircraft Spruce.

ACS still sells it, plus the metal prep phosphoric acid to etch the surface.

https://www.aircraftspruce.com/catal...clickkey=11999

https://www.aircraftspruce.com/catal.../alumiprep.php

BEWARE this stuff is a chromate conversion coating, very poisonous. READ the SDS before you order and decide if you want the risk.

I grit blasted my wheels and magnesium gearbox adaptor. I kept it all dry and immediately sprayed the coating wearing an organic vapor respirator with hepa filters stacked on. Wear rubber gloves, plastic apron. Discard everything when you are done.

The following day I sprayed everything with a coat of clearcoat enamel.

YMMV