hi my name is bd180 i am a newbie welder but been a mechanic for 30+ yrs . i recently read somwhere than in welding a dragrace chassis i should use mild steel filler rod to weld 4130 tubing any input? i'm still trying to deside what material to use for 34ford chrome moly or msdom tubing. thanks bd.

Straight from Lincoln:
Q. What filler material do I use?
A. Although there are several good filler materials, ER80S-D2, is one you should consider. This filler material is capable of producing welds that approximate the strength of 4130. ER-70S-2 is an acceptable alternative to ER80S-D2, as is ER70S-6, although the weld strength will be slightly lower.

Some will use .083" 4130 to fab a rollcage vs. .120" DOM mild, the additional strengh will allow for thinner material shaving a few pounds off the weight. They weld the same, no need to preheat .083 wall 4130, just do as you normally would.

When welding 4130 on aircraft tubing we are required to gas weld and a mild steel filler rod is approved and will make a joint that will be strong enough for a approved repair.No preheat is needed but rewelding the joint is not allowed,it must be ground out and rewelded.
Hope this helps.
ES

although the other comments will work, if you can find 4130 cut wire, it would be prefered. We also back purge all weldments.

NHRA only allows tig on all 4130.

er80s filler is the 4130 process of choice. as mc pointed out. the lincoln process book will answer any process ?? that you have. or call your local test center they will write a process then certify you to that process usally for about 300 bucks. start stacking up those process certs. they pay off in the long run.

Just adding....

shocks are on bushings as well, but they seem to be more conductive...dont know why. some shocks are mounted with heim-type joints that would be very conductive, and would also weld/pit those joints if used as a welding ground.