cleaning transmission case

[preS]

What is the best way to clean the aluminum case of my 901 transmission? Currently it's kind of dull and I would like to get back the aluminum color before putting it back together.

Thanks for your input,

Richard

[911scfanatic]

I thought 901's were magnesium like the early 915 cases?

[Eric911S]

Hello: Use mag wheel cleaner or simple green. If you have a mag case it will be a dull gray color. Thanks Eric

[Scott Clarke]

Scotchbrite pads do a good job.
-Scott

[Alan.uk]

Whilst rebuilding my 70 mag 901 case I had it vapour blasted. I think 69 was the first mag case, it was a one year only, mag case but with the push clutch.



Alan.UK

[Scott Clarke]

Alan-

Wow! Does anyone know about vapour blasting in the US? Alan-
How much did that cost to do?

[Eric911S]

Hello: Remember the mag case will not stay that color for long. You have to paint it or coat it to stop the oxydation from turning it dull gray again. You could have your case media blasted with soda. There should be someone that is doing this on fiberglass cars(Corvettes) in your area. If you have a museum near you they also do this on fossils. Hope this helps. Thanks Eric

[Scott Clarke]

Eric-
What kind of soda is that? Is it done in a standard blast cabinet at standard pressure?
-Scott

[Eric911S]

Scott; I believe they use just standard baking soda at the museum here. They turn the air pressure down to about 20lbs. If you use too much air pressure it turns it into even finer powder. They also use plastic media for Corvettes at low pressure as well. It does not even hurt the fiberglass. I have seen the results and it works great. Another option would be to have the case tumbled at a metal finishing place. Do a google search for these options. If you want to do it yourself buy some aluminum oxide from Harbour freight and blast at 30lbs. Make sure you clean the case afterwords like you are going to eat off of it. One piece of hard media in there and you will grind the parts up. Lastly play sand works also. Just be careful on your cleaning. You can degrease the parts by taking them to a transmission shop that does aluminum and put it in there washer. It is safe for the mag cases as well and is bio friendly. Thanks Eric

[Zeke]

Eric-
What kind of soada is that? Is it done in a standard blast cabinet at standard pressure?
-Scott

I wish I could tell you myself. I have heard about soda blasting for some time, so I tought I'd experiment. I bought some plain ol' baking soda and put it in a little cup blaster. I used this on a CDI unit and it came out fantastic!! You couldn't tell it from NOS, AFAIC.

The thing is, this was terribly messy. I did it ouside and there was a white cloud over the neiborhood. I have no idea what industrial soda is, but the very fine grit of the baking soda on a real small job is way good for a nice patina that is completely unike using even glass beads. Me thinks it would work in a cabinet blaster, but it might cake up in the suction hose. For that reason, next time I'm going to use my cup blaster inside the cabinet and not scare the neighbors.

I wouldn't use any abrasives on the trans case. I have had very good results cleaning AL with hot water and lye. Rinse well, real well. Maybe a touch of vinegar in the rinse to neutralize the lye.