The best of both worlds: Swift assist springs provide
dynamic progressive – linear rate.
Assist springs have two functions. The first is the spring adds a progressive rate to the initial portion of the stroke. This progression can add increased comfort is used on a daily driver coilover setup that has stiff springs installed. It provides racers added softer spring rate progression. Once the assist crushes, the normal spring rate will take over.
The second job is the same as helper springs. They prevent the loss of traction during rebound, and extreme cornering.
Assist springs are designed to repeatedly be fully crushed. Every assist spring crushes to the same height. That allows drivers to change assist springs without resetting the spring perch on coilover without changing ride height.
Helper springs prevent dismounting of springs from perch on coilover
without changing spring rate.
Swift helper springs are specially designed to provide minimal effect on spring rate. Using helper springs allows the spring to stay firmly on its perch when the shock has negative or zero load. Driver should use helper springs if they experience springs coming loose from their perch and/or they can not preload the main spring because of car height issue.