How to Lower a Rear Suspension
- 1). Determine the type of spring used in the rear suspension. If the spring is a coil spring, lower the rear suspension by cutting a coil off the spring. Jack the car up, supporting it with jack stands, and remove the springs. Cut the coil with an abrasive grinder or a saw. Do not use a torch, as the heat will remove the temper from the end of the spring.
- 2). Look at the mounting for the spring if the rear suspension uses leaf springs. If the pad where the spring mounts to the axle is on the top of the axle and under the spring, lower the rear suspension several inches by cutting the pad off and rewelding it to the bottom of the axle. Then mount the axle over the spring, instead of underneath as before.
- 3). Lower a leaf-spring rear suspension a lesser amount by replacing the spring shackles with shorter shackles.
Source...