NHRA vs SCCA roll bar requirements

[Compuguy2142]

NHRA Chromoly roll bar specs are 1 3/4 × .083. General regulations section 21 page 21

SCCA roll bar specs 2700lbs and up are 1 3/4 × .095 Page GCR-91

My question is, to build a roll bar compliant with both rules, will SCCA allow the 1 3/4 × .083 for Chromoly? The rulebook did not specify different thicknesses for DOM vs Chromoly.

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[Norm Peterson]

I suspect not, based on the most recent copy of the Solo rules I have on hand (2017). The weight break to 1.75 x 0.095" in those rules is at 2500 lbs (I have no idea why the GCR would be less stringent than for autocrossing in this respect).

Roll Bars - Appendix C
1. The roll bar hoop and all braces must be of seamless ERW or DOM mild steel tubing (SAE 1010, 1020, 1025) or equivalent, or alloy steel tubing (SAE 4130). It is strongly recommended that roll bars not be constructed of ERW due to quality and strength concerns.

Another reason is that SCCA's rule philosophy is generally one of "if it is not specifically allowed, then it is not allowed".


Norm