Transaxle Casting Repairability

[Citroënbender]

How repairable is this? Hole in cast alloy from diff chamber into bellhousing, approximately three inches by half that.

I can get a used casing, it would be around $300-$600 but the trade off is lack of “matching numbers” originality - gearbox codes and serial are stamped on it.

[383hq]

Without knowing the material, no-one can tell you for sure.
If it is A356 you *might* be ok with very good weld prep and 4043.
Depending on how you weld it, you might get some slight distortion.

Find the material its made from, find the answer.

[prktkljokr]

I had a extension housing for a C4 gearbox modified once with mount for a transfer case, the guy who did it welded aluminium boats ( a friend of a friend), it out lasted the vehicle it was put in .

I doubt if it would be much different alloy than any other automotive aluminium casting, I would try someone who does aluminium welding even cylinder heads and see if they can weld it up.

As long as you do not have any other fractures around the hole leading to anything machined you should be fine, you will have to completely strip the casing and have it hot washed etc to get the alloy clean for welding.

[Franco Cozzo]

JB weld and send it

[Citroënbender]

I don’t think it’s normally a stressed location, that was an anomalous event which created the hole. A bit suspicious of JB-Weld in long term exposure to hot gear oil but will consider Belzona products. (UK made, pirated in China.)

[hawke]

I put some JB Weld on a hole in a dry sump oil tank about 20 years ago, as a temp fix. Still there today - oil temps typically 120 degrees C.

[383hq]

Originally Posted by hawke

I put some JB Weld on a hole in a dry sump oil tank about 20 years ago, as a temp fix. Still there today - oil temps typically 120 degrees C.

And probably safer then using 5356 as a filler at that temp due to potential Stress Corrosion Cracking with some materials/casting types

Also an easier field repair...

[AMB]

Originally Posted by 383hq

And probably safer then using 5356 as a filler at that temp due to potential Stress Corrosion Cracking with some materials/casting types

Also an easier field repair...

This looks more than just a hole. Its got a large gap to span.
Someone good at welding aluminium alloy could easily fix it and hardly noticeable after grinding smooth, but the case would have to be removed and on the bench, and accessible from both sides. Looking at the picture, not sure if you could get to outside of the case.

[Citroënbender]

It’s smashed through into the bellhousing, the clutch cover is just visible through it. So you can access both sides pretty easily, and probably even weld from the bellhousing side with the diff clamshell bolted up to torque as a preventive against warping.

I’m grateful this happened at “granny speed”, 25km/h taking home the groceries from Aldi. At 70+ with the boot in, there’d likely have been a lot more damage to the geartrain.

[383hq]

From the photo, If there are no raised ribs, it's not a stressed location. Modern FEA analysis and die casting put material just where its needed nowadays. Also greater choice of cast materials available...

Welding one side should be good 'nuff, (should you decide to put the time and effort required)

If its die cast, it can be a coin toss. If its a VW die cast, it could well be high in Mg - and use of 5356 would be the go, but if its A356 and welded with 5356, and above about 70deg C in service, a short term (but strong) single pass repair might result.

if its 201/354/355 4135 would be used.

I remember when bell housings/cases had to be a bolted joint -it was a lot simpler back then, and thats without worrying about porosity, hydrogen embrittlement, hot cracking etc....

Or you could just guess and hope, or guess and take it to the auctions. I couldn't. I'm not a Cun!, even though I'm old enough to qualify.

[prktkljokr]

If it has no stress you could do a bodge and clean the surrounding metal, drill a heap of 1/8 dimples and few through holes for it to bite and hold and just Devcon from both sides, 1st pass with some tape on opposite side to hold shape, then remove tape and do other side, I doubt if it will move or leak, did a cylinder head once with the stuff it lasted years.

[Crazy Dazz]

Originally Posted by Citroënbender

but the trade off is lack of “matching numbers” originality -

Lack of "originality," vs dodgy repair. I know which side I'd come down on.

Historically, any attempt I've been associated with, to weld cast alloy, has been a disaster. But I imagine a professional could do it.

Would it need TIG? I've tried MIG welding cast alloy before, and it's been less than satisfactory.