Q. I have a Millermatic Challenger 172 that I love. My question is about race car chassis. Are they constructed of 4130 tubing, and if they are what type of welding machine would be used? Andys' pictures show a MIG machine next to most cars. (Submitted by: Stephen Edgar from Unknown)

A. Most NASCAR stockcars are make of mild steel DOM tubing. Most are MIG welded, however some teams prefer to TIG them together. 4130 material is used mostly for some component parts like control arms, A-frames and brackets.There are a lot of drag race cars that are 4130 material. Most of these are TIG welded, which is a requirement of the sanctioning body.