need some tips from someone who is a master at TIG welding aluminum. trying to repair an aluminum skinned car that has a lot of cracks and damage from years of racing. some of the cracks are where it wraps around the steel tubing and it does not seem to happy when I get near the steel. any thing I can do or ideas on how to keep the arc and puddle happy? also some areas go from around .060 thick to maybe tin foil and it makes it tough to keep the puddle working without it burning away. I am a fair welder but this is pushing my talents so any tips would be appreciated. here is the car. been raced since '64 and has been rolled at least once and end over end once plus other hits so it has been straightened and hammered and abused a lot.

Clean Clean Clean

WIth dirty aluminum I like to take a "pre" pass with no filler to clean the weld area. Run low amps and use the gas to get the area cleaner. I also like to keep a dedicated wire brush for only cleaning aluminum.

you have to do sections of the aluminum and change the current accordingly.I take it you have a foot pedal,just need to throttle it.also,try to rotate the body so its a flat surface to weld on.

I would never claim to be a master but I have been doing it for 40 years.

What are you using for filler? You need something really skinny like .030 or .035 wire.

Same for electrode. For something that thin most likely 1/16 and thoriated would probably help.

https://www.thefabricator.com/thefab...ten-electrodes

I have seen guys weld beer cans. I am not one of them however.

I am sure there are some pros on here. Hopefully one will pitch in here.

It also sounds like the stress areas will need to be annealed

I weld a fair amount of aluminum on custom cars, but don't consider myself and expert, as Mark BAM stated using a smaller tungsten with smaller filler rod should help. Another thing that was mentioned by (Resurrected) was to anneal the area. It sounds as if this piece has seen its fair share of work hardening. What I usually due when working body panels is to spot tig the area to hold it together and then switch to Oxy, Acetylene welding with a torch, flux and 1100 filler rod. By doing this is keeps the weld and area around it from becoming brittle and cracking in the future. It also allows you to hammer the areas around the tubes without fear of cracking what you just repaired.

Make sure as others have stated to clean the area very well with a stainless steel wire brush, you also want to make sure the filler rod is clean. Good luck.

using thoriated 1/16 tungsten and 1/16 filler rod. been cleaning it as best I can, it has been painted, bondo and all metal filled and fiberglassed over the years. took 10 gallons of material off it to get to the aluminum. problem is some of the areas I dont have access to the back side and trash comes up from behind. have been heating it to try and get it out first and that helps but still seems to bleed stuff out.
have not tried annealing it. may give that a try in some areas as this thing has been bent and beat many times and that is not helping me.
I am not one of those that can weld beer cans either.LOL! this car is really taxing my limits at welding.
any thing that can be done to stabilize the arc where it is wrapped tight around the bars?
wish I could get it rotated so it would be flat but right now I have to weld upside down in places which is really pissing me off but it is what it is.
thanks guys

I have tried torch welding aluminum, only to try it, not because I need to. I had no success at all. Anyone who can torch weld aluminum is an artist! That may be worth trying in this case, it absolutely has its benefits
I can TIG razor blades together, and that's easy compared to thin aluminum!

Far from expert, but have learned a few things from a few that know lots more than me.
I am wondering if two things might help...
Getting things clean, I had a few projects where I was using muriatic acid thinking it would get really clean.
I was told use snow bowl instead.
The muriatic actually eats in and exposes too much so oxidation happens before you wed.
The bowl cleaner has hydrochloric also that helps slow the oxidizing but keeps aluminum clean long enough to weld.
You also mention that problem areas are near the frame.
Is it close enough to contact that the frame tubes are leaching the heat from the aluminum sheet?
Maybe pre-heat with the torch so area is hot before the TIG arrives.