How do I choose which hole to mount the control arm to?
See the procedure detailed in the Mm5RLCA-57 installation instructions.
What is "instant center"?
Instant Center (IC) is the location in space, when viewed from the side, about which the rear suspension rotates around as it moves up and down. In the case of the S197 Mustang, it is determined by the geometry of the UCA and the RLCA pivot locations. The IC location needs to be determined in order to calculate the amount of anti-squat geometry that the rear suspension has.
What is "anti-squat percentage"?
Anti-squat percentage (AS%) is the fraction of anti-squat behavior that the rear suspension geometry has relative to full AS (100%). In a rear suspension with 100% AS, none of the forward acceleration forces pass through the springs or shocks, so the ride rear height does not change during acceleration. In a rear suspension with 50% AS, half of the acceleration forces pass through the springs and shocks, while half of the forces pass through the centerline of the control arms.
How does the anti-squat percentage affect launching?
With 100% AS, any longitudinal (front to rear) weight transfer happens nearly instantly during launch. With 50% AS, half of the acceleration forces during launch pass through the centerline of the control arms, and half of the forces go through the springs and shocks. The springs and shocks take time to change length. While they are changing length, they can't conduct the acceleration forces to the rear tires; only after they stop changing length can they conduct the acceleration forces. Since the acceleration forces are delayed in reaching the rear tires, there is less rear tire traction available for acceleration during the suspension motion. This is the main reason why 100% AS geometry gives the most forward rear tire traction.