Topic: Cleaning/Restoring automatic transmission cases

[sparky65]

ADMIN NOTE: The following includes posts post and threads from a number of original threads on a similar subject merged to keep them all together

So I haven't looked at the trans since I pulled it from the car.  I will most likely have it checked out by a trans shop along with the output shaft seals replaced.  What should I do about cleaning it up?  Maybe the shop can do it for me, I just need to know what to ask them to do.

[CharlesTurner]

Trans shops usually have nice cleaning solution.  Tell them you want it brightened up like original.

[sparky65]

How do you preserve the finish after it is cleaned up?  Use the cast aluminum paint or some other clear coat?

[kutzoh]

Was going through the archives looking for the answer to this question and since it wasn't answered I'll ask it again.

How do you preserve the natural finish on the transmission after its cleaned up?

Thanks,
Greg

[jwc66k]

A C4 case is aluminum and as such will not corrode like iron or steel. Aluminum oxide is formed when the case is in the presence of oxygen and that retards further corrosion, so paint or other formal surface treatment is not needed. Get the case as clean as possible with soap and water, thinner, Simple Green (my favorite is Krud Kutter) or anything to remove grease and oil. The next step is simple, steel wool or a light wire brush to get a rough "sheen". We use a stand mounted buffing wheel on a top-loader bell housing and it worked good. Transmission shops have cleaning "stuff" but most leave an slightly oily residue, which will come off easily.
Jim

[bryancobb]

Here's what I did to mine.  There's NO way you're gonna get a transmission shop to get it this clean for a reasonable fee.  I just kept scrubbing mine with a stainless toothbrush and lacquer thinner.

I don't know how it would stand up to judging but I cleared it with PPG Concept and I have 5,000 miles on it now and it looks spotless.

[CharlesTurner]

Not sure if you were wanting any feedback on the pic, but since you put it out there, I guess a couple things piqued my interest.  The finish on the shift rod, looks like it was done in zinc?  Thought these were usually natural steel or phosphate.  Did you find that yellow mark on the parking brake cable lever?  Seen a bunch of them and never found a marking.  The zinc dichromate on the side cover sticks out, seems like that plate is usually natural?

Not trying to pick on you, just interested in these finishes.

[J_Speegle]

Not sure if you were wanting any feedback on the pic, but since you put it out there, I guess a couple things piqued my interest.  The finish on the shift rod, looks like it was done in zinc?  Thought these were usually natural steel or phosphate.  Did you find that yellow mark on the parking brake cable lever?  Seen a bunch of them and never found a marking.  The zinc dichromate on the side cover sticks out, seems like that plate is usually natural?

Agree with Charles (and look forward to your response) that these items are different from what I've seen on Cr4 from the period

[bryancobb]

You guys are the experts.  The servo cap is wrong. The shift rod IS wrong.  These items will be corrected.

As for the yellow paint on the brake lever, It WAS there but I don't know its' origin.  Lots of ways yellow could have got on there.  Thanks for the coaching.  I'll remove it.

The primary focus of this picture was to show how clean I was able to get the case and bellhousing, to see if what I experienced, applied to what the OP was asking. 

I have to say that I am a wrench-head, artsy, engineering type.  I HAVE NEVER had a car judged.  I have ZERO experience in that realm yet.

[kutzoh]

I'm more interested in any "preservation" techniques once the case is cleaned. Does anyone recommend hitting it with a clear coat or as Jim said the aluminum will not corrode and any formal surface treatment is not needed. What about the servo cover and trans pan, which I have read is bare metal, any suggestions to "treat" these to keep them from rusting or does the oily nature of the parts suffice.


Thanks,
Greg

[bryancobb]

Aluminum DOES corrode!  It's prevention is a MAJOR chore for aircraft owners and mechanics.

I posted the picture of mine because I used PPG Concept clear on the case for "preservation."
It is crystal clear catalyzed polyurethane and as you can see in the picture, doesn't look like it's there.
As I said, I have no idea how it will do in judging.

Charles-n-them say Boe-Shield is THE STUFF for preserving natural stuff.

[jwc66k]

Aluminum DOES corrode!  It's prevention is a MAJOR chore for aircraft owners and mechanics.

Aluminum in the presence of oxygen forms a layer of aluminum oxide which resists further formation of aluminum oxide. Aircraft maintenance techniques that polish aluminum skins do so to remove dirt (oil, moisture and other surface maladys), besides it gives ground crews something to do. If you leave aluminum alone, e.g. - unprotected as in no paint, it will not corrode, at least as fast as iron or steel. That's basic physics and manufacturing engineering.
Jim

[bryancobb]

I'm NOT talking about aircraft aluminum skins.  I'm talking about STRUCTURAL components hidden deep inside.

[Murf]

Can anyone endorse a product for cleaning the aluminum transmission case.  The transmission is intact which reduces the options considerably.  Attempted to use EZ off oven cleaner Heavy Duty but on a test patch it turned the alloy black and did little in the way of getting me where I wanted to end up.  Maybe you have used a different brand?  Trying to get a clean surface, hope for a bright finish as when cast.  Thanks for any suggestions.

[Bob Gaines]

Can anyone endorse a product for cleaning the aluminum transmission case.  The transmission is intact which reduces the options considerably.  Attempted to use EZ off oven cleaner Heavy Duty but on a test patch it turned the alloy black and did little in the way of getting me where I wanted to end up.  Maybe you have used a different brand?  Trying to get a clean surface, hope for a bright finish as when cast.  Thanks for any suggestions.

Steam cleaning gets most of the stuff. Power wash doesn't do as good . The heat in the steam does wonders. Then go over it with eagle wire wheel cleaner and various size stiff PLASTIC brushes. It is a mild acid product so wear safety glasses ,gloves and ventilated area that has a drain so when you hose it off (obviously you will plug dipstick)