This worksheet will help you select the correct springs for your vehicle. In order to do this you will need to know what WHEEL RATE you want.

WHEEL RATE is the actual rate of the spring acting on the tire. This value is not always the same rate as the spring rate on the shock. The spring rate depends on where the spring is mounted on the suspension. Wheel rate and spring rate are measured in lb../Inch. See Step 1 to determine the WHEEL RATE.

In order to determine WHEEL RATE you must know

the vehicles SPRUNG WEIGHT and WHEEL TRAVEL. Once you have found the wheel rate, you will need to calculate the SPRING RATE that will be needed for the shock You will need to know the suspension configuration (i.e. a-arm, I-beam, or four-link rear). See figures 1-3.

The SPRUNG WEIGHT is the weight that each shock is supporting (i.e. the corner weight less unsprung weight). Unsprung weight is the tire and wheel, hub, upright, brakes, and about half the weight of the shock and A-Arm or I-Beam. For the rear suspension of a truck, the unsprung weight is the tires and wheels, the entire rearend and half the weight of the shock and trailing arm.

Generally, off-road suspensions will use Dual Rate spring configurations. Our Dual Rate configuration utilizes two springs: a Main Spring and a Tender spring.

The Main Spring is the bottom spring that covers the shaft of the shock. The Main Spring should have a higher spring rate and a longer length than the Tender Spring. The rate of the Main Spring will be the Secondary Rate.

The Tender Spring is the top spring that covers the body of the shock. The Tender Spring should have a lower spring rate and a shorter length than the Main Spring.

A Dual Rate spring configuration will have a Primary Rate that is a combination of the Main Spring and Tender Spring (see Step 4 below). When the Tender Spring coil binds or hits the stopper, the Secondary Rate will take effect.