ssmith Posted October 26, 2022 Share Posted October 26, 2022 Since apparently I feel like fighting uphill battles this week, here goes: There's a rule in section 5.2 (p7 of ruleset 2022 ST1-4 v16.2) that reads: Quote CCR 15.6—Roll cages may be built to provide an unlimited amount of chassis stiffening. Any number of cage mounting points above the minimum required can be used. Any number of additional tubes, including those penetrating the firewall are permitted. Additional tubes converting the vehicle into a tube-frame chassis vehicle are permitted in ST1, ST2, and ST3. This overrides the CCR rule 15.6.2 (p44 / pdf p56 of 2022.2.1 CCR) that would normally restrict chassis stiffening: Quote Chassis stiffening is a side benefit of a good roll cage system, but it is not the intent of these rules. Parts of the cage deemed by the Chief Scrutineer to serve no practical purpose other than chassis stiffening may be considered in violation of the intent of these rules. So stiffening any other part of the car is normally considered acceptable, including shock towers or other suspension mounting points, but for some reason stiffening the rear subframe of some cars yields a penalty while for other cars it does not. Super Touring has a rule in Appendix A (p27 of ruleset 2022 ST1-4 v16.2) that reads: Quote Ford Mustang and BMW E-36 and E-46 M3: "Upper sub-frame connectors" that penetrate and modify the floor pan will be assessed a -0.2 Modification Factor (seen commonly in American Iron Mustangs). Ignoring the wording on whether this applies to all E36 but only E46 M3, or whether it only applies to E36 M3 and E46 M3, I would like to propose that this be eliminated for all BMWs. I can't speak for Mustangs as I do not understand the details of that chassis. In my opinion, this hinges on two issues: 1. Is there a performance advantage? I don't believe there is. Some of the fastest cars in ST4 Norcal and ST4/TT4 Champs do not take the penalty: Cars #38 and #3 do not take the modifier yet #38 easily won TT4 at Champs and both were the two fastest cars in the Sunday Champs race. 2. Is it equivalent (or a step) to building a tube frame car? After all section 6.1.7 (p9 of ruleset 2022 ST1-4 v16.2) states: Quote If a vehicle cannot be driven safely, at full speed, with any of the added tubes removed, it is considered a tube-frame chassis conversion. I don't believe this is a good application of the tube frame rule. A chassis that isn't broken does not need the subframe connectors in order to drive safely at full speed. Instead, the subframe connectors are one way to keep the chassis from tearing apart over the course of seasons. Another choice might be to remove the subframe and fuel tank each season and reweld a new floor pan or weld up any cracks that start forming. However that would be considerably more expensive. So in the end adding subframe connectors is really just a cost savings issue, not a performance issue, doesn't make the car a tube frame car, and is allowed by the ST rules in order to stiffen the chassis. Quote Link to comment Share on other sites More sharing options...
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