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HOW TO RATE COIL SPRINGS WITHOUT A RATER
G=
D=Wire Diameter in Inches
N=Number of Active Coils
D=Mean Coil Diameter in Inches. Mean Diameter is:
I.D. = 1 Wire plus inside Diameter
O.D. = 1 Wire minus outside Diameter
8=A Constant for all Coil Springs
HOW TO DETERMINE ACTIVE COILS OF A COIL SPRING:
Count total number of coils, subtract a coil for each coil that touches, these are dead coils. Ground flat ends are a dead coil. Start count with cut-off end facing you directly above would be one and so on. Not all coil springs are even coiled. You can have 1/4, 3/8, 1/2, 5/8, 3/4 or 1/8 of a coil (Example 10 1/8 coils).
- If you cut one coil from a spring, the rate will increase.
- Increasing wire diameter, will cause a great increase in rate.
- Nothing in spring rate calculation indicates that a coil spring ever changes rate. The rate is determined by material and dimension of the spring. Coil springs don't wear out or lose their rate.
- Spring load determines how much load a spring can support at a given height. The rate only tells how much height will change as load is changed. A spring can lose its load height over time if steel is not heat treated properly. When a spring sags, its rate is still the same as when it was new.
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