Way To Check Roll Bar

[Simon T.]

I have a Miata with a roll bar welded in, the guy I got it from said the bar is SCCA legal (material and size tubing), I WANT to add a front section, and try to make an ITR car. But I want to make sure my bar is good, anyway to tell if it's legal?

[JeffYoung]

Look in GCR.

Find minimum thickness and diameter for your car's weight.

Measure diamter, drill test hole and measure wall thickness.

BUT, no Miatae are classed in ITR....so....you mean S? or A? Not that this matters to the allowed tubing sizes.

[Simon T.]

Oh, oops, is it ITU or something? Regional class for cars that are not classified in any other IT class. My car is not legal for SM or ITA

[JeffYoung]

No problem. Yes, it will either be in ITO/E or U.

Shouldn't affect cage thickness though. Check the GCR on that for yor car's weight and then check your diameter and wall thickness.

[Simon T.]

Ok thanks, I was just asking mainly HOW do I check it, like what tools.

[JeffYoung]

Drill and a micrometer of some sort....

[racer_tim]

Simon, to measure the thickness of a tube, drill a small pilot hole. then with the "stick" end of a vernier caliper, measure the depth of the hole when it hits the other side. Then take the "fork" end and measure the outside diameter. Subtract the first measurement from the 2nd, and you get the tubing wall thickness.