Filler Wire for TIG welding G50 transmission

[Dauner]

Hi everyone,

Car is a 1989 911 3.2 G50. I am wrapping up my full engine rebuild and need to address my broken clutch fork shaft boss. somewhat common failure.

Have a pretty specific question. What filler wire have people used to TIG weld G50 transmission cases? I am welding on a section of 6061. According to the web common wires are 4043 and 5356 for 6061 to cast Al. 5356 is for environments that don't exceed 150 degrees F. 4043 has about half the sheer strength. Both have sort of big downsides.

Anyone with personal experience?

I called the G50 transmission repair guys, and they are not super excited about giving advice due to liability reasons. fully understand.

I can't afford to send my transmission to Patrick or CMS and have them tear down and reassemble.

any advice greatly appreciated!

thx

Mark

[Trackrash]

I asked a friend of mine, who has been a welder for many years, and he said 4043 or any aluminum rod will do.

[Solamar]

Id use 4043. Preheat the area a bit with a mapp gas torch if you can.

5356 seems to be more susceptible to thermo cracking from cooling too fast.

[icarp]

See if you can purchase a broken g50 trans part, then cut off strips for filler rod and make your repair.

[MConn]

Dauner,
Can you share some details of the failure -
Did the open boss break?
Did the trans have the original style shaft, or was it bored out to use the needle bearings?
Was the clutch/PP stock or performance?

I just bored out my bosses to 19mm for the upgrade, and they look thin.

Thanks
Mike

[ClickClickBoom]

The problem with welding aluminum that as had oil on the inside and outside surfaces is getting it clean enough. After you get it to where you get it clean enough, clean it 2 or 3 times more. The problem with castings is the various thicknesses of the casting. I wouldn’t weld it without preheat and a post heat cool down period. My concern is cracking during the cool down. But since it’s cracked you don’t have much to lose.

[Dpmulvan]

Use 4943 far superior to others mentioned for your application. What kind of welder do you own?

[Dpmulvan]

Originally Posted by icarp

See if you can purchase a broken g50 trans part, then cut off strips for filler rod and make your repair.

Your joking right ?? Sounds like something they would do in a Cuban alley using the power line for a stinger.

[Dauner]

Hi Mike,

To answer your questions, I think my build date was 11/88, and so someone at some point did machine out the bores. I think after April, 1989 they came at the 19mm shaft diameter. My engine rebuild project was the first time i had ever separated tranny / engine and so never knew I had a problem. car shifted just fine. as it turns out, yes the open boss had cracked off, and I had been driving for many years with the little metal tab at the end of the clutch fork shaft taking the full force of the pressure plate springs. the broken off half of the boss was nowhere to be seen. It appears someone had tried to do a weld repair at some point but they must not have done a thorough job and the remnant broke off again, possibly slipping thru the opening at the bottom of the bellhousing. A previous owner had full new factory clutch, PP, TO bearing, sleeve, etc. all replaced, and they all appear to be in very good shape. No performance stuff at all.

If and when I do successfully get a 6061 bore half welded on to the boss, I'll definitely post pictures.

mark