Yea, this is a sucker to do. I didn't have access to a torque multiplier so I had to do it with a 4 foot pipe on a 1/2" breaker bar.
I made a 1/2" thick plate that went over the wheel studs and welded an arm to it, then did it on the car using the car lug studs to hold it in place, the bar turning against the floor.
That is so much leverage that you need to be careful you don't pick the car up off of the floor when you stand on the pipe.
I think I tried it on the workbench like in the above picture but I tore the vise loose from the top it being only 3/4" plywood. I figured on the car was "safer". (Yea, that's the term...safer)
For the weld, you need to go back to your "strength of materials" class and calculate the size of the weld needed with an e60 electrode. It's pretty big and the "stick welder" was on like 150 amps.
I calculated that if I stood on the "arm" being 220 pounds that at 36" when the nut wouldn't turn anymore, it would be about right.
I'm not sure that you can do it accurately with an impact gun at 150 psi air pressure? I was more comfortable with my method, and I don't know if I was "fortunate" not to break a leg or arm, but I got it done.
You do need to be concerned with over stressing the gun, the air hoses AND the compressor itself.
Don't forget that the "impact gun" IS going to "kick" when you hit it with full tank and that you can shatter the gear in the gun. I didn't want to take that kind of a chance. I don't do this every day.
The issue is that there is little procedure for accurately measuring the applied torque without the multiplier.
To this day, I still don't think there are any local shops I could rent or borrow a torque multiplier from?
Maybe the "semi" shops have one but none of the big "semi" guys will even talk to me to this day. They suddenly become mute.
They get like $500 an hour with the "vehicle" on the lift in the shop and helping you takes "food out of their kids mouths".
Caution should prevail. Use the black impact wrench sockets, extensions and components. You don't want even a Craftsman forged socket suddenly shattering on you and throwing shrapnel in your direction. This ain't for "kids" to do. You can get killed doing this.
As I recall, I MIGHT have broken the pin on the 1/2" breaker bar on one, then bent the pipe too? I'm not sure? I prefer not to think about that. Gives me chills thinking about how freakin' crazy I really am? Next I'll be catching bullets in cotton padding? Well, maybe not?
You can twist yourself up really good with doing this too? My chiropractor wants to know exactly WTF I do, being so twisted? I think she means my back but I'm not completely sure that's what SHE meant? Maybe that's why people are afraid of me? Hum?