oldopelguy HalfDork
8/4/08 6:01 a.m.

Found a supplier able to make me up some transmission adapters I've been wanting for a while, but the cheap option doesn't have enough thickness to have a proper register for the back of the bell-housing. With the bell housings in question a dime-a-dozen, that's not a big deal, I can TIG the adapter right to the back of the bell, and the cost savings might make this option the way to go.

So, with this in mind I need to clean up the bell-housings for welding. They are aluminum, and while pretty clean they have been exposed to oil. What's the best way to get to oil out of the aluminum to allow for a good weld?

I'm thinking a good cleaning, soap and hot water first, then acetone and/or sand-blasting would certainly get them looking and feeling clean. From there, probably a trip to the powder-coating oven to heat them up and draw the oil to the surface with repeated wiping down with more acetone. Keeping in mind all the parts are thick and this isn't delicate work, does this sound the right way to go or is there some other trick I don't know? Maybe Metal-Ready instead of acetone? Advice welcome.

jamscal HalfDork
8/4/08 6:26 a.m.

The only answer I've found is to clean the exterior the best you can and then pour the heat to it when welding. The first few weld/grind cycles will get all the oil out and you'll soon be able to put down a clean weld.

I've welded a few pontoon boats this way...no way to clean the gunk on the inside...you just have to gob the filler on with a bunch of heat, grind and repeat.

Heating it up in a PC oven sounds like a good idea, but I've powder coated supposedly clean engine castings and the small amount of oil left smokes impressively.

Your plan including sandblasting will probably get you close to clean enough.


daytonaer New Reader
8/4/08 11:36 a.m.

acid (sulfuric?) in water is used to clean Al before anodizing. Check all the DIY anodizing tutorials on how to properly clean the Al, I thought you would soak it in the solution then wash it with water. the NaOH is used to etch the Al, but I don't remember the specifics and the info didn't come to me on a brief search. .

triumph7 New Reader
8/4/08 1:02 p.m.

The product you want is called Alumiprep. It is an etching compound used before applying Alodine. You can probably find it in an aviation supply house like Aircraft Spruce or Aviall.

spitfirebill HalfDork
8/4/08 2:13 p.m.

How thick is the plate you are using and who is going to do the machine work? I need a plate to adapt a Spitfire bellhousing to a Ford type 9 trans. I'm not too far away.

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