Spring Rate Calculator for Independent Suspension

 

When selecting the correct spring for an independent suspension, use this simple formula for motion ratio at the ball joint:(b/a) 2

Spring Rate

  • Measure the length of the lower control arm (dimension a).
  • Measure the length between the lower coil-over mount and the lower control arm inner pivot point (dimension b).
  • (b/a) 2=The motion ratio percentage at the ball joint.
  • Divide the Motion ratio percentage into the desired ball joint rate to find the correct spring rate.

 

Length of the lower control arm (a).

Distance between the lower coil-over mount and the lower control arm inner pivot point (b).

Desired wheel rate.

 =

Motion Ratio percentage at the ball joint

Final Spring Rate