A. One (and only one) coil or leaf spring per wheel must be used. Coil springs must be manufactured from magnetic steel. Rear leaf springs (if used) may be either magnetic steel or an approved composite material. All coil springs must be a minimum of 5 (five) inches in diameter. Coil springs must be wound with all coils being the same O.D., I.D. from the top to the bottom of the spring. The coil spring wire diameter must be the same from the top to the bottom of the spring. Coil spacing must be equal. Round coil spring wire must be used. Coil springs with linear spring rates are the only coil springs permitted. Air springs are not permitted.
B. Front coil springs:
a. The top of the front coil spring must be closed end and ground flat.
b. The upper front coil spring mount must be flat and support the top of the spring 360 degrees.
c. The lower end of the front coil spring must be an open end with a maximum gap of 1/4 inch between the “tail” of the spring and the next coil.
d. The lower front coil spring mount may have a single step to prevent spring rotation and accommodate the open end of the spring. The step of the lower front coil spring mount must not exceed one (1) inch in height. The lower coil spring mount must be a welded integral component of the lower control arm. When installed the lower end of the front coil spring must be supported 360 degrees.
C. Rear Coil Springs:
a. The top and bottom of the rear coil spring must be closed end and ground flat.
b. The upper and lower rear coil spring mounts must support the spring for 360 degrees.
c. Rear steel coil-over eliminators and/or steel/aluminum coil-over kits will be permitted. The coil-over eliminators and/or coil-over kits must conform to the shock and spring rules.
d. Only one coil spring per wheel will be permitted.
D. All rear springs must have a tethered and/or cable system in place to securely fasten them in position in the car. E. One and ONLY ONE coil spring will be permitted on the lift bar and/or brake spring. Lift bar and/or brake springs must be a minimum of 5”-inches in diameter. Progressive springs will be allowed on the lift bar and pull bar.