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Coil Spring Rate Calculator

All Measurements in inches
Wire Diameter Spring Outside Diameter Number of
Active Coils		 = Coil Spring Rate





Spring Rate Calculator
for Coil Over Mounting Angle

 When mounting coil overs, check the degree of angle and use this to correct the spring rate

 
Angle 10 15 20 25 30 35 40 45
# to use below .96 .93 .88 .82 .75 .66 .59 .50

Desired Spring Rate

From Chart Above
 =

Spring Rate Needed





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

    • 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 ball joint rate.
 =

Motion Ratio percentage at the ball joint

Final
Spring Rate




Torsion to Coil Spring Rate Calculator

The effective bar length is the distance between the 2 bearing surfaces
or the distance between the two smaller outer diameters
or the distance between where the bar tapers.

Diameter
of Bar		 Arm Length Effective
Bar Length

=
 Torsion to Coil
Spring Rate




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