Fixing a mounting tab on automatic transmission?

[CGCINC]

A friend called tonight... he just rebuilt his transmission for his truck and broke a mounting tab off of it.
He want's me to weld it back on.

I can weld Aluminum pretty well but I've never worked with cast Aluminum so any tips, hints, tricks you wanna share would be greatly appreciated!!??

[sportbike]

grind it, clean it, then heat it up a bit with a torch to try to get any crap to come out. Then grind and clean it again. Turn the balance to a high level of cleaning and just run over it to clean it rather than actually weld. Hit it with a ss wire brush and have at it. Probably best to just build it up with bead after bead after bead and then grind and drill to re-build the ear rather than try to weld teh ear on, depends on how much was broken.

[Rodsmachineshop]

depends on were welding on trans were is the tab at since automatic trans can damage inside seals if over heated when welding

[CGCINC]

depends on were welding on trans were is the tab at since automatic trans can damage inside seals if over heated when welding

Yeah, he did say one shop he called said they would need to tear the tranny apart to fix!?!? He just rebuilt it and didn't want to do that so he called me.
I'm not sure exactly where it's at, he said he would bring it by in a few days for me to look at.

So if it is in a critical place, can you build weld and just let it cool between welds and still be ok?

[jakeru]

Good advice above. Although once you get it clean, no need to run high EP% A/C balance, IMO. You'll need lots of power (and high EN% will be helpful) to melt (and penetrate if joining two pieces together) thick aluminum casting. Good case for a Helium mix too.

If you're doing build up, you don't need as much EN%, just melting the surface (no deep penetration) will work fine. Going over the area to be welded to ensure it's clean before hitting real heat to it is a great idea. You want the A/C etch to leave behind white, not black, then you know it will weld nicely.

rodsmachine is right about potential damage caused by welding... depending how close heat-sensitive parts are to area to be welded. Welding "hot and fast", and in small steps (allow time in between to cool) will help keep the heat off sensitive parts. If you have a real demanding problem, you can use a wet rag to keep things cool. Just don't get yourself into a scenario of welding dripping wet aluminum, because the H20 can cause porosity from the hydrogen.

Check out these 2 links - probably not identical to what you're going to do, but probably somewhat similar, both are welding cast aluminum motorcycle transmission/engine cases to repair broken off mounting lugs while the transmission was mounted in place:

http://www.everlastgenerators.com/fo...nt)-jakeru-s-9

http://www.everlastgenerators.com/fo...-TIG-build-up)

[Rodsmachineshop]

what kind of trans ford , Chevy , dodge make and model trans . i rebuild automatic trans at my shop so know bad points were to weld

[undercut]

Would pulse help to keep the heat down too?

[sportbike]

Would pulse help to keep the heat down too?

It would, but in this case, the base material is likely very thick and it probably would keep the heat "too down".

[CGCINC]

what kind of trans ford , Chevy , dodge make and model trans . i rebuild automatic trans at my shop so know bad points were to weld

Not sure on this one but when he brings it in I'll let you know.