the last sentence in this paragraph is unclear to me without a picture. Are they just suggesting that you have a crossbar low down on your main hoop? Or a continuous rectangular shaped main hoop with the lower corners (with 3x radius) somehow attached to baseplates?
(on re-read, I see that this applies to Production cars, not IT, but I'm still curious what they mean)
thanks,
bruce
C. Fabrication - Open and Closed Automobiles
The main hoop shall be one continuous length of tubing with smooth continuous
bends and no evidence of crimping or wall failure. The minimum radius for all bends shall be
three (3) times the tube diameter measured from the tube centerline. Whenever possible, the
roll hoops should start from the floor of the automobile, and, in the case of tube frame
construction, be attached to the tubes by means of gussets or metal webs in order to
distribute the loads. On automobiles of frameless or uni-body construction, consideration
should be given to using a vertical roll hoop of 360 degrees completely around the inside of
the automobile and attached with suitable mounting plates.