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Posted by: toolguy Apr 4 2016, 03:56 PM

I just went thru a long process of figuring out how to paint my Mag / Gasburner rims. . Initially I was going to powder paint them as my nephew has a powder business and it would be no cost to me. . . After some in depth research, we found some potentially big issues with baking / powdering mag rims. .

1st issue was excessive gassing during the baking period. . seems magnesium has a lot of porosity and can produce bubbling in the powder even if they are pre-heated and powdered hot. .

2nd issue was about metal deterioration from high baking temps. . that turned out to be less of an issue if you bake them under 400 degrees but there is lots of internet chat about the metal losing its strength with higher temps. .

3rd issue was what to do if I needed to remove the powder in the future. . powder is very hard to remove with blasting, the usually shop practice my nephews business uses to remove powder is to bake at 600 and burn it off which would destroy the magnesium. . or dip them in a chemical stripper, which I didn't think would be any too positive either. .

4th issue. . Apparently magnesium absorbs and reacts badly to humidity and the atmosphere. . that is what causes it to turn blackish and produce a whitish corrosion on the surface. . This can end up lifting any powder or paint applied over a contaminated surface. . therefore it needs to be painted or somehow have the surface sealed directly after blasting. .

The end of the story was that I bead blasted the factory finish completely off, which had some very hard and durable primer coats. . The base coat was a yellow coat and then a blue secondary coat over that. . took about an hour a wheel to get all the multiple nooks and crevices stripped bare of the factory coating. .

Then each wheel was promptly primed in PPG DP40 metal etching primer. Let these dry overnight. The next morning I shot them with color correct silver single stage Urethane with flattener to achieve the semi gloss surface, Three full coats with 30 minutes between coats.
Total investment for the PPG paint and primer, with catalyst, reducer and flatener came to $320, plus the 5 hours to strip the rims and another half day to paint them.
Probably the hardest part was coming up with a silver paint that didn't have a 'metallic' sparkling appearance. Ended up having one mixed with the smallest flakes available.

I had gone to a good quality paint and body shop before all this when i was in the planning stage and asked for an estimate for them to blast and paint. . Their 'Friend' discount price was $1500 total, priced at $100 per rim to blast and $200 a rim to paint for a set of 5 with center caps. .

If nothing else it's a good sense of accomplishment and the saved money was the bonus. .


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Posted by: sb914 Apr 4 2016, 04:02 PM

They look great! Nice job

Posted by: ConeDodger Apr 4 2016, 04:03 PM

The 5th issue is they are Gas Burners! They're worth a fortune and if you screwed them up??? They look good though! Congrats!

Posted by: somd914 Apr 4 2016, 04:12 PM

Nice job

Posted by: veekry9 Apr 4 2016, 04:34 PM

Do you have a pix of the backs?I assume they were done the same.
Color correct,a number of the mix?
Nicely done,the reason I ask.
We were always cleaning post blasting with 'Gunk brand brake cleaner',the compressor lube present in most blaster's supply a contaminant.

Posted by: Cairo94507 Apr 4 2016, 04:36 PM

Wow- those look terrific. And, I really appreciate that you posted about your experience and research.

Once my car is done and back in my garage, I plan to find a set of gas burners for it as I love the Six with gas burners and will most likely have to refinish them. Your wheels look perfect.

Posted by: 76-914 Apr 4 2016, 04:39 PM

Posted by: Mueller Apr 4 2016, 04:40 PM

Looks great...years ago I had a set of modular Ronal Racing wheels with the magnesium centers. When I 1st got them I stripped them and polished 'em up. They looked great for a while. Needless to say I ended up painting them not too long afterwards.

Posted by: DCJosh Apr 4 2016, 08:33 PM

How do you know they are magnesium and not aluminum? I have not seen anything that says that they are magnesium. I'm genuinely interested. Thanks.

Posted by: Johny Blackstain Apr 4 2016, 08:43 PM

My favorite factory 914 rim by far. They look great

All Mahle 5 lug rims were made out of magnesium, not aluminum. If they're made out of anything else they're not genuine Mahle's. Four lug Mahle's were made out of aluminum. Somebody out there makes 5 lug replicas & they are not made out of magnesium.

If I ever did a 5 lug conversion to an LE I would choose 5 lug Mahle's only. Expensive yes, but somehow seems proper to me.

Posted by: mepstein Apr 4 2016, 08:44 PM

QUOTE(DCJosh @ Apr 4 2016, 10:33 PM)

How do you know they are magnesium and not aluminum? I have not seen anything that says that they are magnesium. I'm genuinely interested. Thanks.

Posted by: DCJosh Apr 4 2016, 08:55 PM

QUOTE(Johny Blackstain @ Apr 4 2016, 09:43 PM)

My favorite factory 914 rim by far. They look great

All Mahle 5 lug rims were made out of magnesium, not aluminum. If they're made out of anything else they're not genuine Mahle's. Four lug Mahle's were made out of aluminum. Somebody out there makes 5 lug replicas & they are not made out of magnesium.

If I ever did a 5 lug conversion to an LE I would choose 5 lug Mahle's only. Expensive yes, but somehow seems proper to me.

Posted by: porschetub Apr 5 2016, 03:17 AM

QUOTE(Johny Blackstain @ Apr 5 2016, 03:43 PM)

My favorite factory 914 rim by far. They look great

All Mahle 5 lug rims were made out of magnesium, not aluminum. If they're made out of anything else they're not genuine Mahle's. Four lug Mahle's were made out of aluminum. Somebody out there makes 5 lug replicas & they are not made out of magnesium.

If I ever did a 5 lug conversion to an LE I would choose 5 lug Mahle's only. Expensive yes, but somehow seems proper to me.

Posted by: Johny Blackstain Apr 5 2016, 07:15 AM

QUOTE(porschetub @ Apr 5 2016, 04:17 AM)

,they have the look and nothing comes close,imagine if they could retool them to 6,7,8 '' with the right offset that would be a dream come true .....sorry just woke up