Know the spring.
Compare the options.
Start with door weight. Find a spring combination, explore wire sizes, or match a spring already on your truck.
Adjust spring wire
Calculator notes +
Spring sizing
Enter the door weight and select the actual drums, door height, and 15″, 12″, or low-headroom (LHR) track. Calculations assume level horizontal track. Slide the wire size to compare lengths and cycle estimates.
Matching a spring
Lock in the spring you have. The calculator sizes a companion for the remaining spring rate and shows the cycle estimate for each spring. The lower estimate is the pair’s limiting value.
Best fit
Automatic selection uses the smallest supported wire meeting your cycle target, preferred length, space allowance, and spring-rate tolerance. You can change these preferences or choose another wire size.
Cycle estimates
Cycle life is estimated for new springs, not remaining life for a used spring. IPPT means inch-pounds of torque per turn. Total IPPT adds the rates of the springs in the assembly.