Hmmm, not much help here.
Yes, actually I have been reading the Australian Bellytank thread. This is one of the reasons for asking. I have notinced many car built with rec tubing for the main rails.
It actually makes sense to run solid mount front and rear axles, I keep thinking along the lines of transition and dampening.
The Rulebook is interesting, it like SCCA has to cover a multitude of different types of cars.
As far as driver protection, yes, I see definate construction. It seems resonable, nothing out of the ordinary.
One thing though, and maybe I missd it, the vehicle weight doesn't factor into the cage requirements (tubing size).
I miss type, yes, if a smaller engine class and speed below a threshhold, lighter tubing.
In SCCA, the requirements depend on the weight of the car, at one time a 4000# car was 2" x.120 tubing.
My initial question was chassis, not roll cage. The latter is easy, the other has many factors.
Thanks, John