Bolt in rollbars Q & A

You build a cage/bar to meet certifacation, one does not get a cert to build cages for NHRA.

Basic roll bars (that allow) is 1 3/4" by .118 wall min or.083 Moly
If a cage is to be installed the dia can be reduced to 1 5/8" x .118 or .083 moly
Now here is the problem, standards have changed when it comes to wall thickness in mild steel with the 1 5/8", they can still call it .120wall when it measures out .114 and that will get you bounced if the check it. So as a chassie builder you have to use the next up in wall size which is .134 (and measures as such)
The next problem is that most local metal supplys dont carry it and you have to buy it from a chassie supply house unless you can afford to buy a large amount