If you have ever wanted to know what your spring rate is here is the formula to figure it out.
SW - to the fourth power
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8CM - to the third power
No what does that mean you ask, I'll explain.
S= the torsional modules for steel which is 11,250,000
W= wire diameter
8 is a constant for all coil springs using this equation
C= number of "active" coils
M= mean diameter of the coil
Here is an example.
The 2000 S-10 (non ZQ8) uses a spring with a wire diameter or 0.625.
The overall diameter is 5.625. The mean diameter is 4.86 (simply subtract the width of the wire from the overall diameter to get the mean diameter)
Number of active coils is 5.75. (see pic at bottom)
Now with that info I'll show you how to do the equation.
11,250,000 X 0.765 X 0.765 X 0.765 X 0.765 which equals 3,852,993.4
That is the top of the equation.
8 X 5.75 X 4.86 X 4.86 X 4.86 which equals 5,280.4
That is your bottom number
3,852,993.4
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5,280.4
Or, 3,852,993.4 divided by 5,280.4 which equals 729
So the spring works out to be 729 lbs/in
If I was to cut a half coil off the spring rate would be raised to 799 lbs/in.
Example of "active" coils. Part of the text on the bottom right was cut off. It should read, Blue marks equal turns of the coil. Started from the bottom up in this example. The come out to 6 1/4.
MOOG coils spring part numbers and chart. I should mention the spring rate seems to be slightly off.
Pick up, sadly it only goes to 1996.
http://bbb-carb.com/coilsprings/Chev...S10-Pickup.htmBlazer to 1997
http://bbb-carb.com/coilsprings/Chev...S10-Blazer.htmChart.
http://bbb-carb.com/moog_Coil_Springs.htm
