Re: Roll cage tubing diameter 1.5 or 1.625? (rockit)
Per the 2003 SCCA GCR, the following roll bar tubing is required:
Vehicle Weight Tubing Size
Up to 1500 lbs 1.375 x 0.095
1500 to 2500 lbs 1.500 x 0.095
over 2500 lbs 1.500 x 0.120 or 1.625 x 0.120 or 1.75 x 0.095
The tubing material per the SCCA GCR must be seamless, or DOM (drawn over mandrel) mild steel tubing (SAE 1010, 1020, 1025 or equivalent), or alloy steel tubing (SAE 4130).
The main hoop tubing behind the driver must have a diagonal in the main hoop and a horizonal bar running the width of the main hoop. The horizontal bar will intersect the diagonal.
I feel the most important elements of a roll cage are the mounting plates. In the Improved Touring classes, a mounting plate can be a maximum of 100 square inches.
Be sure to have the mounting plates contoured to fit the rocker box. The mounting plates should extend onto the vertical section and top of the rocker box for additional strength. In my race Wabbit, the roll cage tubing is welded and braced to the top section of the mounting plates on the rocker boxes. I used 1/8 inch thick mounting plates. Definitely do not install the mounting plates only on the floorpan as the the floorpan is not strong enough. Regards, WWR.