In building my $2011 challenger, I'm trying to figure out if it's possible to make it useful for any competition besides the GRM $201X. I think SCCA Solo is my best bet. If it was to race SCCA, it would go straight to A Modified. I'm trying to figure out what is REQUIRED to compete in AM, not just suggested. Suggestions are nice, but requirements are what matters. From what I can tell, here are REQUIREMENTS that a closed top Solo car would require (condensed from SCCA solo rules):
3.3.2 Roll Bars A roll bar meeting the requirements of Appendix C or a roll cage meeting the requirements of Section 9.4 of the Club Racing General Competition Rules (GCR) is required in all A Modified (AM). The roll bar or roll cage height may also be reduced in the same manner for cars in the Prepared category with a full original equipment windshield assembly and a standard (as defined herein) hardtop which has been bolted securely in place. APPENDIX C - SOLO ROLL BAR STANDARDS A. BASIC DESIGN CONSIDERATIONS 2. In a closed car, it must be as close as possible to the interior top of the car. 3. The roll bar must be designed to withstand compression forces resulting from the weight of the car coming down on the roll structure, and to take fore-and-aft loads resulting from the car skidding along the ground on the roll structure. 4. The two vertical members forming the sides of the hoop shall not be less than fifteen inches apart (inside dimension). B. MATERIAL 1. The roll bar hoop and all braces must be of seamless ERW or DOM mild steel tubing (SAE 1010, 1020, 1025) or equivalent, or alloy steel tubing (SAE 4130). 2. The size of tubing to be used shall be determined on the basis of the weight and speed potential of the car. The following minimum sizes are required and are based upon the weight of the car without the driver. a) Over 1500 lbs – min 1.500” o.d. x 0.120” wall or 1.750” o.d. x 0.095” wall b) Over 1000 lbs – min 1.250” o.d. x 0.090” wall c) Under 1000 lbs – min 1.000” o.d. x 0.060” wall 3. Each mounting plate shall be at least 0.080” thick if welded and 3/16” (0.188”) thick if bolted. A minimum of 3 bolts per plate is required for bolted mounting plates. 4. All bolts and nuts shall be SAE Grade 5 or better and 5/16” minimum diameter. C. FABRICATION 1. One continuous length of tubing must be used for the hoop member with smooth continuous bends and no evidence of crimping or wall failure. D. BRACING 2. All roll bars must be braced in a manner to prevent movement in a fore-and-aft direction with the brace attached within the top one third of the roll hoop, and at an angle of at least thirty degrees from vertical. E. MOUNTING PLATES 1. Roll bars and braces must be attached to the frame of the car wherever possible. 2. In the case of cars with unitized or frameless construction, mounting plates may be used to secure the roll bar structure to the floor of the car. The important consideration is that the load be distributed over as large an area as possible. A backup plate of equal size and thickness must be used on the opposite side of the panel with the plates through-bolted together.
I'm trying to interpret this to have the most absolutely simple roll bar possible. For example, if I have a 2000 pound car, I could have a hoop that is 1.5 x .120" and two 1.25" tubes that attach 3" down from the top of the hoop, then go rearward at 30°. Another example: with a 1400 pound car, I could have a hoop that is 1.25 x .090" and two 1" tubes that attach 6" down from the top of the hoop, then go forward at 60°. These tubes all terminate at the bottom of the car with .080" plates.
Am I reading this right? I can't stand how complicated and wordy this stuff gets, SCCA rulebooks drive me bonkers. Thanks to any help. If somebody has a clear picture/example of a bare minimum roll bar, that would be helpful too. I've had a hard time wading through the internet BS to find some reliable info.
Bryce
