I-35 Speedway will be utilizing the USRA Alternative Rules for those other sanctioned B Mods which would like to race with the USRA B Mods at I-35 Speedway. The rules can be found as Article 17 in the USRA B Mods rules. Listed below are the rules;
This must be decided before the season starts but may be removed at any time. This is not an option for drivers to use from race to race. All race cars utilizing these Alternative Rules may utilize a maximum three (3) inch spoiler. All race cars not utilizing these Alternative Rules are not allowed any spoiler. All other USRA rules apply.
Body: An eight (8) inch rear filler panel must be utilized. Sail panels may be a maximum forty-three (43) inches
Rear suspension: A thirteen (13) inch maximum vertical rear spring centered on rearend housing with solid spring
perches is required. A sixteen (16) inch minimum to nineteen (19) inch maximum rear suspension links and a
twenty-three (23) inch minimum straight panhard bar mounted behind rearend housing is required. Rear shocks
must be mounted behind rearend housing, Rear chains only, and if used must be mounted solid to axle housing
and frame and must be loose at ride height.
Engine: Standard Engines and Crate Engines only (Concept Engines are not allowed). Stepped headers are not
allowed. Maximum compression ratio of 9.0:1 with a maximum 6800 RPM rev limiter for Standard Engines. E85
fuel is not allowed. Cold air boxes are not allowed.
Rearend: Quick change rearends are not allowed. Full spools and/or lightweight gears are not allowed.
Transmission: Clutchless transmissions are not allowed (all gears must function).
Wheels: Only three (3) and four (4) inch offset wheels are permitted. One (1) inch wheel spacers on four (4) inch
offset wheels are permitted. Any other wheel spacers are not allowed.