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It will be a while before I can drop 3Gs+ on new 17" wheels and tires. After seeing Garth's posts on the Toyo Proxes tires, I'm thinking of going that route for now. Has anybody out there refinished stock Campi wheels? I recall a post from Jack indicating that you need to be careful because magnesium is quite porous and there is some type of "sealer". I don't mind spending a little time and elbow grease. Or should I just have them dipped (in what?) and re-paint using the grey/argent classic paint from Eastwood? Suggestions?

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1. Clean the wheels
Thoroughly clean and degrease the wheels. Also, remove the DeTomaso center caps.

2. Anneal the wheels
Bake in an oven at 370 for 1 hour. Let cool overnight in the oven. This is best done with an oven outside. Acrid smoke will billow out of the oven, fill your house and set off the smoke alarms if you attempt this in the kitchen. And your house will stink for several weeks. I tried to bake just 1 wheel when my wife was gone for a weekend.

3. Strip/bead blast the wheels to remove all old paint.
Note: If the wheels still have the original factory paint and its in great shape, it's not necessary to remove it all.

4. Seal Prime
Prime/seal the wheels with Zinc Chromate to protect the magnesium against corrosion. I used the yellow spray cans of zinc chromate from Aircraft Spruce to prime my wheels:

5. Paint the wheels
I used Eastwood Light Argent Silver wheel paint:
The color is almost spot on!

6. I used Eastwood Diamond Clear for the final topcoat:
The wheels look great!

Overall, it was A LOT of work. A fellow club member reported that he dropped his wheels off at a local body shop and had them resprayed for $50 each (IIRC). I think I would go that route in the future given all the work it was to strip and paint the wheels.
How about touch ups? I pulled my 8" campi's off the front of 7102 and found that during some maneuver of mine last summer that allowed full downward extension of the front suspension the inboard edge of the rim (under where the bead seats) was scratched, all the way around, both wheels. It even chewed up a portion of a stick on wheel weight. It was evidently caused by the upper A arm edge just above the outboard ball joint bolt.
Now I pretty sure I remember when the "suspension extension" happened and I'm not going to do that again. And I don't need a full wheel refinishing, but I would like to touch up these circumferential scratches to protect the magnesium. As it's a area that can't normally be seen (usually it's covered in brake dust) maybe I could just apply only a primer to seal them? Is the Zinc Cromate the only primer that will stick to/seal magnesium? What color is it?
maybe I could just apply only a primer to seal them? Is the Zinc Cromate the only primer that will stick to/seal magnesium? What color is it?

I don't know if it's the "only" primer that will stick to magnesium, but it is the correct primer to seal magnesium against corrosion. It's available in yellow and green as far as I know. I used the yellow. I believe it's also available by the pint or quart, so you could brush it on to small chips, or merely use the spray can and spray a small amount into the cap and then use a small brush to touch up your chips. Do the same with the silver color as well.
The best alternative to Zinc Chromate (which I understand is getting hard to find because it is supposedly a carcinogen) is to powder coat the wheel. Without Zinc Chromate to seal the wheel first, ordinary paint is insufficient. The added benefit of powder coating is that the temperature used is about the same as that required for annealing. Also remember that, in order to anneal properly, the wheel must be cooled very slowly. This is best accomplished by making sure the powder coater does your wheels as the last job of the day, and leaves them in the oven to cool overnight.

No matter what, you will need to bake your wheels before powder coating or painting in order to bake out the contaminants, or else you will get outgassing that will ruin the finish.

Before painting your wheels, make sure you have them Zyglow (dye)tested for cracks. The wheels are prone to cracking for two reasons. First, unless they are regularly stress relieved through annealing - which most people don't do, magnesium work-hardens until stress cracks appear. Second, any scratch (such as a curb scuff or scratches from wheel weight mounting) will allow moisture and contaminants into the porous magnesium, which will immediatley start corroding until it is weakened to the point of cracking. Now that your wheels are probably more than 30 years old, they really should be checked. I have heard it said that they should be done every ten years, but I think that is probably too cautious.

Cracking and other damage can often be repaired, but make sure you give your wheels to someone who knows magnesium. Welding magnesium is both tricky and dangerous. Always be sure to stress relieve after welding, because the heat from the welding causes stress in the material that needs to be released.

Do your refinished wheels a favour and use adhesive wheel weights. As I already mentioned above, clip-on weights will scratch through your nice new finish, and allow contaminants into the magnesium, which will immediately begin to corrode again. Another trick I use is to lubricate the hub before mounting the wheels (I use Vaseline but maybe others will have better ideas on this)because this is another area where corrosion tends to occur. I'm not sure my Vaseline idea will help, but I'm hoping so because damage to the hub is often impossible to repair. Finally, I am very picky about who I allow to mount my tires. The last thing you need is to have some idiot in a hurry scratch your new finish or, worse yet, break your wheel.

Mike Drew and Jack DeRyke have written excellent articles on refinishing magnesium wheels. If you want copies, PM me with your e-mail address and I will send their information to you. Or you can contact them directly.

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