Rule book discrepancy: ROLL BAR
 

If I'm reading the NHRA rule book correctly, there is a discrepancy on pg. #76, 4:10 Roll Bar.

In diagram, 4:10, it states, "All materials must be 1 3/4" O .D. mild steel ................except A, (rear braces that go into the trunk) which is 1 1/4" O.D.

In the paragraph just above the diagram, it states: "Rear braces must be of the same diameter ,,,,,,,,,
as the roll bar.

Which is it? Can I use 1 1/4" for the rear braces or do I have to use 1 3/4"?

Re: Rule book discrepancy: ROLL BAR
 

Wow, I never noticed that, and it does need clarified.
Kits all come with 1 3/4" for all tubes.

Better check with your Division Tech director for a clarification....I'm going to do the same this weekend.

Re: Rule book discrepancy: ROLL BAR
 

That discrepancy has been in the rule book for a long time. I remember noticing that sort of thing and asking about it 15 years ago as it effected me at the time. I think it was all 1 3/4" if I remember right, but not positive.

Re: Rule book discrepancy: ROLL BAR
 

The cross bar that the seat bolts to is the "A" bar. Not the rear bars. Hope this helps.
Rich

Re: Rule book discrepancy: ROLL BAR
 

Rich is correct. In older rule books using this picture there was an arrow from the "A" to the cross bar that has been deleted somewhere but the intent remains the same - all parts of the roll bar must be the same size EXCEPT the cross bar.

Re: Rule book discrepancy: ROLL BAR
 

Here's a question, does the hoop have to be a single piece? What I mean is, I have a bunch of 8ft pieces of 1.75 tube. I am building the roll bar and 8ft is not long enough to go from floor up over and back down to floor. Can I use two pieces of tube and run a joint or splice tube inside? (not a class car but could relate)
I need a piece approx 10 1/2ft long to do it in one piece.

Re: Rule book discrepancy: ROLL BAR
 

The hoop has to be one piece. That is why a 50 pound chrome moly kit has to be shipped truck freight for $200, grrrr.

Re: Rule book discrepancy: ROLL BAR
 

The 8 feet might get you a J shaped main hoop like i run. The lightest legal roll bar. The main hoop comes up from the left rocker over my head and then drops to the passenger side rocker. There is one side bar and one back brace. The crossbar is about 3 feet long and i can still access the rear seat area.
It doesn't help chassis strength but weight is about 40 lbs less than a normal 6 point.

Re: Rule book discrepancy: ROLL BAR
 

That's a good idea I never thought of! I might of found some cheap heavy wall 1.75 tube that looks to be 10ft or so. If it doesn't pan out I might go with the J bar.