The purpose of the shock absorber is simply to limit the motion of the spring during compression and rebound cycles. If the vehicle is not equipped with these motion dampers, the up and down motion would multiply until the vehicle was alternately trying to leap off the ground and to pound itself into the pavement.
Contrary to popular rumor, the shocks do not affect the ride height of the vehicle. This is controlled by other suspension components such as springs and tires. Worn shock absorbers can affect handling; if the front of the vehicle is rising or falling excessively, the "footprint" of the tires changes on the pavement and steering is affected.
The simplest test of the shock absorber is simply push down on one corner of the unladen vehicle and release it. Observe the motion of the body as it is released. In most cases, it will come up beyond it original rest position, dip back below it and settle quickly to rest. This shows that the damper is controlling the spring action. Any tendency to excessive pitch (up-and-down) motion or failure to return to rest within 2-3 cycles is a sign of poor function within the shock absorber. Oil-filled shocks may have a light film of oil around the seal, resulting from normal breathing and air exchange. This should NOT be taken as a sign of failure, but any sign of thick or running oil definitely indicates failure. Gas filled shocks may also show some film at the shaft; if the gas has leaked out, the shock will have almost no resistance to motion.
While each shock absorber can be replaced individually, it is recommended that they be changed as a pair (both front or both rear) to maintain equal response on both sides of the vehicle. Chances are quite good that if one has failed, its mate is weak also.
REMOVAL AND INSTALLATION
1997-98 F-250HD and F-350
- Raise the vehicle and secure on support stands.
- Remove the self-locking nut, steel washer, and rubber bushings at the upper end of the shock absorber.
- Remove the bolt and nut at the lower end and remove the shock absorber.
- When installing a new shock absorber, use new rubber bushings. Position the shock absorber on the mounting brackets with the stud end at the top. Install the upper bushing, steel washer and self-locking nut at the upper end, and the bolt and nut at the lower end.
- Torque the upper mounting studs to 18-22 ft. lbs. and the lower mounting nuts to 40-60 ft. lbs.
- Hold the shock absorber stem and remove the nut from the top of the shock.
- Raise and safely support the vehicle.
- Remove 2 lower retaining nuts and remove the shock absorber.
- Install 1 washer and bushing to the top stem of the shock absorber.
- Place the shock absorber up through the coil spring.
- Install 2 lower retaining nuts. Tighten the nuts to 19-25 ft. lbs. (26-34 Nm).
- Lower the vehicle.
- Install the bushing, washer and retaining nut to the top of the shock absorber stud. Tighten the nut to 34-46 ft. lbs. (47-63 Nm).
- Road test the vehicle and check for proper operation.
- Raise the hood and remove the upper shock absorber retaining nut and upper shock absorber insulator.
- Raise and support the vehicle.
- Remove the lower shock absorber retaining nut and remove the shock absorber.
- The installation is the reverse of the removal.