Muncie case finish

[G A.]

I have rebuilt the M21. Now 6 months later I've decided I don't like the mottled looking case. Yes, I should have done this before the rebuild but what can I say??
My first choice is to return the case finish back to it's natural state without paint. I have tried a little 'Alumaprep' which is some type of acid my maintenance techs use on occasion when fabricating parts for a plane. I wasn't satisfied. The case still had an irregular finish. Painting it I guess is an option, but not my favorite. What have you used?

Dan

[Joe L.]

Re: Muncie case finish

I have rebuilt the M21. Now 6 months later I've decided I don't like the mottled looking case. Yes, I should have done this before the rebuild but what can I say??
My first choice is to return the case finish back to it's natural state without paint. I have tried a little 'Alumaprep' which is some type of acid my maintenance techs use on occasion when fabricating parts for a plane. I wasn't satisfied. The case still had an irregular finish. Painting it I guess is an option, but not my favorite. What have you used?


Dan

Dan------

All Muncie main cases are an aluminum sand casting. The folks that restore intake manifolds should be able to restore the finish. However, I'm sure you'd need to have the transmission completely dis-assembled and send them a bare case to work with.

[Michael F.]

Re: Muncie case finish

Depends on what you are striving for. If you aren't going by the book, paint with aluma-blast and move on.For as near a factory finish, strip the tranny and send the case out to be (re-skinned).Acid based aluminum cleaners will remove the finished look. Leaving an uneven gray color.I painted mine (helps to strip off all old paint and use very light coats of aluma-blast). TiP: Remove as many bolts as possible (leave them with a factory finish. I think that would be black phosphate. Or replace them after you paint the trans.

[Lyndon S.]

Re: Muncie case finish

You could kind of paint it, with some krylon dull aluminum. You take some paint and spray it in a bowel that has some lacquer thinner it. That should give you a paint on the lacquer , then lightly spray a mist coat on the case, then dip a paint brush in your paint mixture then work that onto your trans case. Work it into the case and you should end up with a natural looking clean aluminum part. Your are just trying to tint the part not really paint it. The paint will soak into the pours of the aluminum it might take you a few try’s to get it just like you want it. But just keep working on it an once you get the hang of I think you will like the results. Also those cases or real porous and maybe seal it up some where it wont weep so much.

[Timothy B.]

Re: Muncie case finish

I agree with Lyndon completely.

Take some dull aluminum with actone or lacquer thinner and mix to soup (so it's very little paint) in a cup and with a rag or brush work it into the case to make a uniform appearance and it's good to go.

[Alan S.]

Re: Muncie case finish

Hi Dan,
I did something very similar to Lyndon and Timothy.
Having the 'soup' quite thin seems to act like a stain on the aluminium and evens out the appearance.
Regards,
Alan

[G A.]

Re: Muncie case finish

Ok. Thank you all. Though I should have done as Joe suggested, I do like the thinned paint approach which I believe is the method I'll apply.

Dan

[Timothy B.]

Re: Muncie case finish

Mix a LITTLE flat black in there with the aluminum paint and it will tone down some.