Quick Spring Tuning

You need these 2 specs from your build:
Total Weight
Front Weight %

This is a formula I have used for a good balanced spring setup.
Front Rate = Total weight x front weight % / 2
Rear Rate = Total weight x (1 - front weight %) / 2

Here is an easy example...
Total Weight = 2500lbs
Front Weight % = 43% (.43)

to calculate the front...
2500 x .43 = 1075 now 1075 / 2 = 537.5lbs

to calculate the rear first calculate your rear rate...
1 - .43 = .57 now plug that into the formula
2500 x .57 = 1425 and then 1425 / 2 = 712.5lbs

The explanation for dividing by 2 is that Forza spring rates are stated per corner. Unfortunately this means that when you get through the initial part of the equation, you have only calculated the front or the rear of the car. You have 2 wheels (corners) per front/ rear hence the dividing by 2.