Automotive Plus Twin vs Single Hoop Roll Bar for NA/NB

[1600Dave]

The twin hoop one meets pretty much NO part of CAMS specs for roll bars apart from using the correct type of tubing. Needs to have a single piece main hoop, has no diagonal bracing.

The single hoop one wouldn't comply as it needs a diagonal that runs from top of main hoop on driver's side to base of main hoop on passenger side. The dual diagonal arrangement with each finishing in the centre of the car would mean it isn't compliant.

I would be sceptical of the positioning of the two backstays as well, they appear to be welded too low on the main hoop, should be closer to the top of the main hoop. I stand to be corrected on that one as I haven't taken much notice of one of the bars in the flesh.

Basically, diagonal must be "configured as defined in Drawing J-18 or J-19 with the upper end of the diagonal attached on the driver’s side."

The statement that they use CAMS specification tubing is correct, but tubing size is less than one page out of 20 pages in the CAMS document (google CAMS Schedule J for the full CAMS document).

Again, none of this is an issue for track days / mtorkhanas / etc that don't require a logbook or a roll bar. You can run anything you like unless it is actually deemed "unsafe".

[twr7cx]

Thanks for the detailed reply. It’s interesting to know regardless of not being necessary for my current needs.

[greenMachine]

Single/double hoop is not acceptable unless it is a monoposto.

Main hoop needs a proper diagonal.

That is just the obvious stuff. More HERE (Schedule J).

On preview, what Dave said. Note Schedule J is for non-road registered cars (ie logbooked racing cars). I have registered my BD bar with CAMS, and it is now being transferred to the SE which will (all going well) be a logbooked road registered car for 2018. Not many people will want to do that, so as Dave says, if your car is road registered you need only satisfy a scrutineer that it is not unsafe.

[RS2000]

Strength of Roll Bar Structure
* The TB roll bar mounts exceed the State/NCOP Regulation of 6mm thick mounting plates and a minimum of two M10 8.8 grade high tensile bolts at each mount.

How many bolts on the main hoop feet? Minimum of 3 is required for Cams compliance.