Dune buggy TIG welding (aluminum motor mount repair/improvement) - jakeru's #9

[jakeru]

I just did a pretty dramatic aluminum TIG build-up on a motor mount lug for a dune buggy that got broken off, and that the customers had lost. They bought the dune buggy this way - with damaged motor mount.

Here is the machine (looked like a hoot!):


The damaged mount was actually a transmission mount, for some honda motorcycle engine that was mounted in the dune buggy. There were two front mounts that pivoted, and the rear (transmission) mount connected to a threaded turnbuckle that could be lengthened or shortened to adjust the chain tension. (Chain connected output gear to a gear on the rigidly frame mounted drive axle.)

Broken motor mount lug (view from above):


Anyhow, it was tricky because they wanted me to weld the aluminum lug around the steel turnbuckle, with the turnbuckle installed. (This was to help save them the effort of removing the engine/trans assembly to remove the gear, to install the turnbuckle.)

There was only one way the turnbuckle could be oriented so it could still be swung around into installed position without interfereing against the frame. I managed to pull it off. After cleaning the fractured aluminum material, I started performing the TIG welding aluminum build-up on the surfaces that would stick out through the turnbuckle. Then I installed the turnbuckle and continued the aluminum build-up. When it came time to build the aluminum up over the bolted bushing that connected to the turnbuckle, I used a lot of heat and got a nice, clean molten puddle going and flowed it right over the steel bushing. It was beautiful.

Used my Everlast Super200P at up to full 200 amps AC TIG mode (using footpedal to control the power this time), 20% EP AC Balance and with a pretty decent duty cycle building up that thick lug.
Completed weld repair (from above):


Completed weld repair (from below):


Oh, I almost never need to use the stubby backcap on my TIG torch, but I did it for this job so I could weld on this lug without interfering on the frame. The shortest 3/32" tungsten I had was sticking out a ways, so I just put on a big #8 cup (on the stubby gas lens collet body) and it ended up working quite well. Welded outside in a light wind (sometimes pretty still air) OK at 15 cfh argon flow. I used 5356 filler for strength. It seemed to wet in OK to the base metals. (Honda die cast aluminumn seems to weld nicely.) I built the aluminum lug up much wider and probably thicker too than it was originally, to add some strength.

I also wrapped a cotton shop towel around the transmission output shaft and periodically wetted/drenched it with water, to attempt to save the output shaft seal and keep the transmission "happier" through the welding heat. You can see in the "after" photo, the red shop rags stained the aluminum from the heat. (Next shop rags I buy, I'm making sure to just get them bleached white, or undyed.)

I advised the customers to add some compliant or spherical bushings where the turnbuckle mounted to the frame, or at least used two nylock nuts and install until the nuts just start to make contact with the bracket. If they cranked down hard on the nuts, the turnbuckle would be torqued/stressed, so I advised against them doing that.

But anyhow, they were happy as their main goal was just to go dune buggying this weekend with their new toy. It seems like they should be able to do that.

I also repaired some really gross, amateur-quality steel wire feed welds mounting the muffler to the frame. Didn't get any "after" pictures of those, but basically I just ground out the bad nasty welds, and TIG deposited fresh ER70S6 filler in it's place. Nothing too fancy.


The reason the muffler mounts cracked probably (besides the bubble-gum quality welding), was that the exhaust system was rigidly bolted to the motor, and also to the frame via these welds. So the muffler welds were functioning as a motor mount of sorts. (Bad design, IMO, I did inform the customer.)

This whole job took me ~2 hours. Customers were happy, they get to go dune buggy riding this weekend. I did advise them to drain the trans fluid, inspect for burned color/odor, and replace with fresh trans fluid, and also that there is chance transmission output shaft seal was heat damaged (look for evidence of leaking), and if so to replace the seal.

[Timberwolf]

That's just a glorified go cart. Good fix though. I've come across more of those scary wirefeed welds on frames the past few years than I'd like to admit. Scares ya for 2 reasons....first the go cart manufacturers aren't concerned with safety and just throw an inferior product out there that has a short life span. Second, some peckerhead trusts their life (and sometimes the lives of their kids) on welds like that. This case looks like a mounting tab, but I usually see where the frame has cracked from stresses and it has then had bird droppings pile on top until it held. Scary.

[SeanMurphy265]

I hope you got to take that bad boy out for a spin!

[DVA]

I love the picture of the bad welds, reminds me of my friend trying to weld his fince.

[67cudafb]

Looks like real tough place to weld not pretty but looks like it should hold. The old welds show just because you own a wire feeder does not make you a welder. Good job.