Quote:

I am putting a rollbar in my 71 duster built for the F.A.S.T. class. I am trying to figure out the lightest, legal bar I can put in.

From reading the rule book I can run 1 3/4" .083 chromoly bar hoop with same size d/s sidebar, no p/s sidebar and equal sized rear braces.
With a 1 1/4" .065 cross bar.

Anybody ever build a bar like this? Approx. weight? Difference in weight of mild steel?
I have 2x3 frame connectors through the floor that I imagine will give it all the stiffness it really needs, so the bar is really only to appease tech.

Thanks guys.



A friend built a cage similiar to this for his NMRA 'stang and although it passed tech & fortunately has never been tested the chassis guy said he wouldn't drive it. His argument was that between welding 2 dissimiliar metals (mild & CM) the varied tubing widths & where the owner wanted the bars placed (kinda like a stock car cage) he didn't feel it was worth the risk. Now it DID pass tech & he built it with the owner sitting there & telling him how he wanted it & we are talking a mid/low 8-second car here but I tend to agree with the chassis guy. Just because it passes some rules doesn't mea it SHOULD be run. As to the weight saving ---I'm told CM is 2/3 the weight of MS plus MS doesn't fatigue or become brittle like CM