Eibach helper springs are used to prevent the main springs from becoming loose on the spring seat and spring divider when the suspension is unloaded at full droop. See diagram below. At ride height when the vehicle is sitting on the ground, the helper spring is fully compressed. When you launch the vehicle, the helper spring prevents the spring just below it, from digging into the side of the shock. A helper spring, unlike a tender spring, has very little spring rate, and therefore has no effect on the suspension characteristics of the vehicle.