The 1964 Ford F-100 had a standard leaf-spring suspension set up, common to all pickup trucks to this day. Leaf springs are layered metal strips located at the rear of the truck providing a spring action. The axle leading from the rear end to the rear wheel crosses over the center of the leaf spring. Lowering a 1964 F-100 requires installing a suspension kit with the desired lowering measurement. The job requires going under the rear of the truck to change the leaf-spring shackles.
Place a block in front of both front wheels. Raise the truck using a floor jack under the rear-end housing until the rear wheels are slightly off the ground. Set two jack stands, one on each side of the frame, directly in front of each rear wheel. Carefully lower the Ford onto the jack stands and the raise the jack enough so it is tight to the rear-end housing. This prevents the axle and rear-end assembly from moving when the shackles are removed.
Locate the shackles at the rear of the Ford F-100 leaf spring, between the tire and shock absorber. Loosen both the top and bottom bolts using both the 13/16-socket and box wrench, one on each side of the bolt. It may be possible to loosen the top bolt using only the socket. Note the tightness of the bolts to get an idea of how tight the new shackle bolts need to be.
Remove the bottom bolts from the shackle. It may be necessary to jiggle the shackle assembly with a small tire iron to remove the bottom bolts.
Jack the rear-end housing enough to loosen the pressure on the top bolts. Remove the top bolts, install the new lower shackles, and hand-tighten the top bolts on both. Lower the floor jack enough so the lower bolt holes line up. Install and hand tighten the lower bolts. Use the tire iron to manipulate the shackles if necessary.
Tighten the two bolts on each shackle using the tightness of the old bolts as a reference. If not, tighten the bolts until snug, then turn the wrench one-half turn more.
Raise the jack to remove the jack stands, lower the jack and remove the blocks from the front wheels.
