How to Lower a Ford F100
- 1). Drive the F-100 somewhere out of traffic and with a lot of room to the sides; the flatter the surface, the better. Put the truck in "Park" and pull the parking brake up. Empty out the truck bed and the cabin. Jack up all four corners of the F-100 by sliding the car jack under the frame, jacking it up and then sliding in a jack stand. Make sure all four corners are equally elevated. Remove the wheels from each corner with the tire iron.
- 2). Unbolt the L-beams from both front wheel suspension setups. Use a car jack to compress the spring and then carefully pull the spring out from the suspension. Repeat this process for the other front wheel. Then, slide in the new lowering spring and bolt on the lowering L-beam. Repeat the installation on the other side as well.
- 3). Unbolt the U-bolts that secure the rear leaf springs to the rear axle. Then, unbolt the shackles that secure the leaf springs to the truck's frame. Take the old leaf springs out and then bolt the new lowering leaf springs in with the U-bolts. Use the lowering shackles that came with the lowering leaf springs to attach to the frame.
- 4). Bolt on all the wheels and then lower the truck off of the jack stands. The truck will sit lower now but no part should be scraping the ground. Take the F-100 for a test drive to make sure nothing is dragging and that you are still capable of getting over speed bumps.
Source...