Transaxle Painting? Options

[pete]

I want to clean, prep and paint my '74 transaxle. I was thining of using a POR 15 product. Is there a problem with doing this? What type of metal is the trans case? My car is just a Sunday drive. I've read that some people think painting a trans could cause over heating which if this is true painting it with POR 15 would be a real problem considering it creates a completely non-porous surface. Any thoughts would be helpful. Thanks.

[70_914]

I have painted early aircooled vw cases and had no problem. Why is magnesium supposed to be hard to paint? Motorcycle manufacturers paint magnesium wheels all the time. I found this online and it looked useful, from a website about restoring vintage aircraft:

Process:

Here is a safe process to follow for stripping, preparing and painting Magnesium control surfaces.

Supplies needed:

Paint remover (your choice), although there are some preferred types for magnesium that are less caustic for this type of metal. I don't have a list to provide at this time.

Magnesium metal prep, Poly-Fiber has a product called Magnadyne (about $4.50 per Qt.) Locations of distributors that sell Magnadyne


Action:

1.) Remove control surface

2.) Take Weight and Balance optional or required

3.) Strip and smooth surface clean & dry

4.) Apply conversion coat & dry

5.) Apply Non etching epoxy primer

6.) Apply top color coat, then check balance with-in spec.

7.) Install and check tension & rigging



For magnesium you want to strip to bare metal, clean with water and soap and scotch-brite pad (the gray fine grit if possible) and inspect the skin etc.



Prep the magnesium:

Beech/Raytheon provides a Mil-spec Mil-C-3171, AMS 2475 Conversion Coat process for magnesium called DOW 7 and DOW 19. If you search "google" with the term, "Conversion Coat" you will find the pdf file to download. This involved process is not required for existing control surfaces, but Beech or their subcontractors used it on the bare metal magnesium parts originally by utilizing dipping tanks.



For repainting all you need to do is use some of the brush on types. The company Polyfiber www.polyfiber.com/where has a product called Magnadyne (about $4.50 /Qt.) that you mix with water (follow directions by manufacturer). Poplawski uses a product from Eldorado Chemical, there are others too. This stays on about three minutes and then wash off with water. Dry the control surface very well. Use a hair dryer or heat lamp or forced air if heated. You have to get rid of the moisture !!!!! Don't touch the surfaces with your bare hands either, get some cotton gloves etc.



Get ready to apply the primer:

Wipe down the entire control surface with MEK (of course it's bad for you, so are Krispy Kreme fat pills). Use a non etching epoxy primer. Make sure you use a NON etching epoxy primer. Did I mention non etching epoxy primer!!! Good. Polyfiber has a brand and so do all the rest.



Get ready to paint the control surfaces:

You can use what ever paint you want over the NON etching epoxy primer including Acrylic Enamel (may be lighter weight for older ruddervators), Imron or other Poly Urethanes etc. Remember many of the painters at the aircraft paint shops started out by painting automobiles and the more paint the better. We all know that this is not the case for ruddervators or control surfaces. When you select the paint shop for your airplanes, are you talking to a salesman or to the person that is going to actually paint your airplane ??? Go and talk with the person that is actually going to paint the airplane. When you call Poplawski, guess what, he is the same person that actually paints the airplane. (OK, so he's booked up for a year or more).

Now see if you can get the control surfaces to balance according to the Beech specifications.

http://www.vintagebonanza.com/prep_magnesi...or_painting.htm

[ArtechnikA]

...Why is magnesium supposed to be hard to paint?

It's not.
Of course manufacturers get to start with new, virgin parts that haven't been exposed to oil for 30 years and have no existing corrosion to be concerned with.

'The Deal' with magnesium is that if you do somehow manage to encapsulate a bit of corrosion or there is film-penetrating damage, it can turn horrible and powdery without you knowing it (for a while...).

That's something to be said for the Gibbs approach.

And those were excellent links you provided - thanks for that !