2004 Ski-Doo Racing Handbook, Page 19Get this manual
SECTION 03CHASSIS PREPARATION
Coil Springs
The free length of coil spring is the length with no load applied to the springThe spring rate of coil spring is defined as the amount of force required to compress the spring one inchIf 100 pound force compresses spring inch it is referred to as having rate of 100 lbfin (pounds per inch)If 150 pounds of force is required to compress spring inch then it would have rate of 150 lbfin (see following illustration)
Most springs are designed as straight rate springThis means that the spring requires the same force to compress the last one inch of travel as the first one inch of travelExample: 100 lbfin rate spring will compress one inch for every 100 pounds appliedA force of 200 pounds will compress the spring inchesA 300 pound force will compress the spring inches and so onThe 150 lbfin rate spring will require 150 pounds to compress the spring each one inchTo compress this spring inches it will require force of 450 pounds (see following illustration)