Topic: Cleaning a transmission case

[Skyway65]

I’m trying to figure the best way to clean the case of my C4 transmission.  From the research I’ve done so far it seems that bead blasting the whole thing is the way to go to get the stains and 45 years of grunge off of it.  What other procedures would work?  Pros/cons? Comments?  As usual, thanks for all the help.

[J_Speegle]

Not really a perfect answer just some ideas and comments

1- If you bead blast You will likely have to seal it real well or disassemble it and when finished it will not look like it did originally but instead the texture will be altered and a bit mono tone.  I might try blasting it with walnut shells instead if going that direction. Another possibility (once clean) would be aluminum wheel cleaner or lye based oven cleaner

2- Remember that the machined surfaces will need to be redone. This can be done with fine sandpaper and a block in many cases

3- You'll need to remove things like fittings, tubing and linkage and refinish them individually in most cases

4- When you finish don't forget the right style of rear oil seal with the long dust shield

[Bob Gaines]

Now my 2 cents . I would not bead blast it. You will never get the correct finish back . If very greasy that might be a saving grace for the surface underneath. The trans shops or powdercoat shops have ovens that bake the grease off and turn it to ash or even the cleaning process that is like a giant dishwasher that the transmission shops use. That would be for a disasembled case. Steamcleaning would work very good for a sealed assembled case . The point is to be as non aggressive to the smooth aluminum finish as possible. Now if the finish has been beat to hell and previously treated to a bead blast then you will not be gaining anything by being gentle. If you bead blast you will have to treat the now open pores of the metal otherwise it will oxidize quick if exposed to hot and cold wet and dry cycles. If you are able to clean the smooth metal then after you get the grease off it is a matter of using the aluminum wheel cleaner and a stiff plastic brush-not steel or brass. I like eagle brand WIRE WHEEL Cleaner (not to be confused with wheel and tire cleaner)for just about everything light rust removal ,brass cleaning ,aluminum intake cleaning to name a few. This would be the a great product to use here. It has acid in it so use gloves and safety glasses as well and protect surrounding objects. I am used to it so it doesn't hurt my hands anymore (started wearing the throw away latex ones anyway)but a well ventilated room is advisable . I kind of like the smell but others may not(probably bad for you). You may have to go over it a couple times to get the finish desired.  I have also seen some C4+C6 transmissions completely painted with alumi blast that didn't look too bad . Definitely less work. Making the best decision for you will depend on what your expectations are and if driver or show car etc. I hope this helps. Bob

[J_Speegle]

Another thought (if disassembled) would be to hot tank it (at a engine rebuilder)

The big challenger for any of these methods would be keeping the case from staining again after what ever cleaning you choose

[rockhouse66]

I cleaned a stained SB aluminum bell housing with Simple Green.  I saturated, waited, brushed, saturated, brushed, etc.......  It turned out pretty nice, but took a while.  At least it still looks original; bead blasting ruins the part as Bob pointed out.

[Skyway65]

Thanks for all of the ideas.  Since I am doing a concours trailered restoration, the car will not be driven, I will forgo the bead blasting for a more gentle approach. 

[buckeyeresto]

If you bead blast it aluminum prep will bring back alot of the original luster and seal the pors.  also you can buff it with aluminum compound and get the shine your looking for

[Skyway65]

After 3 hours with the Eagle Wheel Cleaner Acid the trans is definitely looking better.  It certainly has a way to go with all of the hardware etc needing to be done, but the aluminum is looking a lot better.  Slow going, but the results are good.

[Bob Gaines]

Have gotton used to the funny smell yet?

[Skyway65]

It's funny, after three hours I smelled nothing (had a decent mask on).  My wife came out and reprimanded me for working in all that stink.  I guess you just get numb to the smell after a while.

[Bob Gaines]

Or burn your sniffer out. 

[Skyway65]

After 3 more hours of scrubbing and rubbing it's looking pretty decent.  The best part is that I found some stuff at Wal Mart called "NevR Dull."  Apparently this stuff has been around forever.  It cuts through the tarnish and dirt on the aluminum relatively quickly when you use some #0000 steel wool with it.  An added bonus is that there are no fumes or acid that might kill you . Now I just need to get all the bolts, brackets and other attachments done.

[Bob Gaines]

Gary, are you using the never dull and then going over the surface with the wire wheel cleaner? I have never used that product in conjunction with the wire wheel cleaner . I am curious if it helps things along or are you saying you would use it as a single application product by itself on the aluminum case? I have to do a aluminum intake and am formulating a plan of attack.

[J_Speegle]

After 3 more hours of scrubbing and rubbing it's looking pretty decent.  The best part is that I found some stuff at Wal Mart called "NevR Dull."  ..............

Isn't this stuff like Ajax or Bartender's Buddy?

[Skyway65]

Bob- First, I used the Eagle Wheel Cleaner (acid) that you recommended.  That cut through the heavy coating of grunge.  It took a lot of scrubbing with a bronze brush and some Scotch Brite.  After the big gunk was off I switched over to the NevR-Dull, it seems similar to Brasso.  It comes in a can with some sort of cotton rag that is impregnated with the liquid.  By wiping this stuff all over the aluminum and then helping things along with some fine steel wool, the aluminum comes pretty clean in a hurry.  The hard part is trying to reach into all of the little nooks and crannys, but at least the wife stayed happy and I didn't need a mask.