Welding cast aluminum, How much warping? Options

[bondo]

People weld cast heads all the time.. could I get away with welding large portions of a transmission case? (902) I have a wacky idea that just might work...

[Aaron Cox]

you can weld up engine cases....so i cant see why not.

interested in what your doing..... 902's had a thin intermediate plate....and a big heavy case.

spill it royce - whatchu doin?

[bondo]

QUOTE (Aaron Cox @ Nov 7 2005, 02:43 PM)

you can weld up engine cases....so i cant see why not. interested in what your doing..... 902's had a thin intermediate plate....and a big heavy case. spill it royce - whatchu doin?

Here's the thought..

Case is aluminum.. Twice as strong, conducts heat twice as well. Twice the weight too, but but compared to the internals it's not that big a deal. It'll be lighter than any 915/930/G50.

The intermediate plate flange is thinner, but they're both hollowed out, and the 902 is aluminum, so it's stronger. One possible disadvantage is that the pinion shaft bearing is retained by 4 bolts instead of 6, I'm not sure if that matters much.

So what I could do is cut out the offending sections of the case and weld in new ones a little farther out, so the ring gear can be flipped for mid engine use. I have had good luck welding cast aluminum before, but I don't know if it was a similar alloy or if I just got lucky. I would use a 914 ring and pinion. (902 output flanges are different, and I heard a rumor that the diff is weak)

So there's my wacky idea, have at it! (IMG:http://www.914world.com/bbs2/html/emoticons/smile.gif)

[Aaron Cox]

i wanted to build a 914 trans using an AL case too...

bolt patterns and stuff are different on the intermediate plate (im told - havent confirmed) and that the Ring gear cant be flipped (im told - havent confirmed)

you are doing a lot of beefing up for a v8.....
you should be fine with a cooler and./or a Billet int plate......

[bondo]

QUOTE (Aaron Cox @ Nov 7 2005, 03:23 PM)

i wanted to build a 914 trans using an AL case too... bolt patterns and stuff are different on the intermediate plate (im told - havent confirmed) and that the Ring gear cant be flipped (im told - havent confirmed) you are doing a lot of beefing up for a v8..... you should be fine with a cooler and./or a Billet int plate......

I'd use the whole case, so bolt pattern differences won't matter.

The cutting and welding I'm talking about would allow the ring gear to be flipped.

I haven't yet verified that it can be converted to sideshift, but I'm guessing it can.

With the aluminum case, a cooler would probably become unnecessary due to the extra thermal conductivity. I already have the case, so unlike the billet intermediate plate, it's free. (IMG:http://www.914world.com/bbs2/html/emoticons/smile.gif)

[Aaron Cox]

bolt pattern - i mean the sideshifter nosecone wont fit.

[Brett W]

Why not just use the Audi gearbox?

As far as welding cast aluminum, yes you could weld that and probably not have any problems. I would use a 4043 rod and preheat the tranny to at least 350. You should clean it really well and do not run a continous bead. Weld a little then roatate the piece, weld some more, then put it back in the oven to even out the heat. This will take a very long time to do, then you will have to have a way to machine it parallel with the other side cover. If not you will creat all kinds of issues.

You will still suffer from the problems that plague the tranny in High HP applications. The pinion doesn't have enough support for high torque loads and the ring gear is too small.

[bondo]

QUOTE (Aaron Cox @ Nov 7 2005, 03:43 PM)

bolt pattern - i mean the sideshifter nosecone wont fit.

I'd use the 902 nosecone and fabricate a bracket to mount it.

[bondo]

QUOTE (Brett W @ Nov 7 2005, 03:49 PM)

Why not just use the Audi gearbox? As far as welding cast aluminum, yes you could weld that and probably not have any problems. I would use a 4043 rod and preheat the tranny to at least 350. You should clean it really well and do not run a continous bead. Weld a little then roatate the piece, weld some more, then put it back in the oven to even out the heat. This will take a very long time to do, then you will have to have a way to machine it parallel with the other side cover. If not you will creat all kinds of issues. You will still suffer from the problems that plague the tranny in High HP applications. The pinion doesn't have enough support for high torque loads and the ring gear is too small.

Cool, thanks. I shouldn't have to do much if any machining, as there will be plenty of material holding the diff bearing area in place after the offending bits have been removed.

I think the only way to know for sure if it will work is to try it..

[Katmanken]

Iffin there is any heat treat on that tranny it's going to go bye-bye at the weld area.

T-6 precipitation hardening goes to T-0 (annealed).

Not sure if the tranny has any heat treating, but most aluminum car parts do as T-0 is pretty soft.

BTDT

Ken