mig or tig?

would mig run to hot? thats what i hear

 

Try the welding/fabrication forum. You'll probably get your answers faster in there.

 

mig or tig. depends on your skills. i prefer tig myself but i get lazy sometimes and use the mig. for the floorboards i would use mig. for the panels the tig would be better. yes the mig will run too hot for these. you would have to tack weld several tiny spot weld type of welds and dab then with a damp rag quickly to prevent the surrounding metal from absorbing too much heat. tig has a smaller heat affected zone near the weld. also you must not remove the mig torch from the weld you put till after the sheilding gas stops coming out. then dab and move on to the next weld. i have frozen steel bars in the past and used magnets to hold them to the back side of a weld area so slow heat absorbtion when welding but i did that with stick and flux core welding procedures. if you could get smaller bars like 1-1/4 inch flat bar pieces in place behind your quarter panels then you might be okay running mig here. but be careful and try shorter stitch welds of like half inch at most