Lotus Elan

Magnesium Care and Feeding

PostPost by: TWebb » Tue Oct 25, 2022 12:18 am

Any recommendations for maintaining the exterior appearance of a magnesium bell housing and diff carrier?

Thanks
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PostPost by: nmauduit » Tue Oct 25, 2022 5:15 pm

I've used a non yellowing epoxy varnish on some parts, that is baked 30 min. at 150°C in an oven after 2-3 days polymerization at room temperature. Supposed to stand 180°C afterwards, as well as oil, fuel or salt...

Quite glossy but since these parts are hidden it may not matter much.

https://www.restom.net/fr/250-alufilm-4040.html local to me, but there should be equivalent elsewhere...
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PostPost by: Roland » Sun Nov 06, 2022 9:42 am

I run a non lotus car that has Magnesium alloy wheels, these will probably be an alloy with lower Magnesium content than your bell housing.

They can be a right pain because the magnesium bubbles/oxidises under the coating and that happens fast even in good environments. I have just recoated them but you need someone who knows what they are doing and a chromate primer must be used. It isn’t cheap to get them done properly.

For an engine component like a bellhousing I think it may cause more problems coating it. If left bare the magnesium will oxidise and form a protective layer which to my knowledge is stable but won’t look great.

Maybe a coating like ACF 50 might work rather than a permanent coating. This product comes from the aircraft world but it will need topping up every year. An aircraft fitter I knew years ago used to regularly spray magnesium castings with a 50/50 mix of light oil and mineral spirts.

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PostPost by: vstibbard » Sun Nov 06, 2022 9:58 am

https://www.gibbsbrand.info/car.html
I use Gibbs products above to “feed” bare magnesium wheels,Porsche 7R crankcases, Porsche & hewland gearboxes and all mag parts on my 26R.
It stops the oxidisation effectively, I lightly spray twice a year.
The wheels on the 26R were painted by a local aircraft maintenance firm at some cost. It’s been in ten years with no bubbling or signs of corrosion.
No affiliation.
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PostPost by: Roland » Sun Nov 06, 2022 12:47 pm

Yes used Gibbs previously on air-cooled Porsches and it is good. I switched to the ACF 50 just because it seems to need topping up less often with the heat under the back end.

I am up in Scotland and actually use the ACF 50 (and the thicker Corrosion Block version) as protection for the winter under all my cars including daily drivers.
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PostPost by: Ianashdown » Sun Nov 06, 2022 5:48 pm

We used to use a Dow treatment to preserve the surface, I think there are more modern and better treatments available now. Do a search for Dow 7 and you’ll get a load of information.

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PostPost by: vstibbard » Mon Nov 07, 2022 10:57 am

I’ll check out ACF50 next time I need a refill
Thx
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PostPost by: StressCraxx » Mon Nov 07, 2022 4:42 pm

Another product is called Alodine, it's a chromate conversion coating. It's available from places like Aircraft Spruce. Read the Safety Data Sheets. All of these chromate conversion products are extremely toxic so the proper PPE and precautions must be taken.
There is no cure for Lotus, only treatment.
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