a threaded piston damper cylinder with a piston rod extending therefrom, wherein the threaded piston damper cylinder is coupled to a frame of a vehicle and an end of the piston rod is coupled to a control arm of the vehicle;

a pre-load collar having an inner member having an inner member top end and an outer member, wherein the inner member is adjustable relative to the outer member and wherein the inner member is provided with inner threads to receive the threaded piston damper cylinder at the inner member top end;

a jamb nut, wherein the jamb nut is threaded onto the threaded piston damper cylinder and engages an upper surface of the inner member, thereby locking the inner member into position by friction between the jamb nut and the inner member;

a tender spring having a top end, the tender spring receiving said pre-load collar therein; and

a spring divider supporting said tender spring and received within a main coil spring, wherein the inner member of the pre-load collar engages the top end of the tender spring to adjust stiffness of the tender spring, wherein the inner and outer members have an elongated tubular shape, said inner member having outer threads for threadingly receiving said outer member and said outer member having inner threads corresponding to the outer threads of the inner member, and wherein both the inner and outer members are rotatably adjustable relative to each other via a threaded engagement in order to adjust an overall length of the adjustable pre-load collar.