The 1997-2002 Ford Expedition (4WD) is built with the following rear suspension components:
1997-2002 Ford Expedition (4WD) Air Springs (x2) - commonly referred to as air bags, a plastic and rubber bag that is fitted on top of the strut that uses pressurized air as a cushion instead of a metal coil spring to hold a vehicle off of the ground and off of its wheels. These are the number one cause of all air suspension leaks. All air springs all go bad at about the same rate. If one is leaking, the others will not be far behind. For a proper repair, all of them need to be replaced at the same time.
1997-2002 Ford Expedition (4WD) Shock Absorbers (x2) - metal tubing filled with gas-charged hydraulic fluid that is connected to the wheel of a vehicle in order to reduce the effects of vertical travel on a rough surface which controls the bounciness, and therefore comfort, of a vehicle.
1997-2002 Ford Expedition (4WD) Air Lines- tubes that run from a compressor to the air which carry pressurized air to the air bags in order to adjust the height of the vehicle, respectively.
1997-2002 Ford Expedition (4WD) Compressor Assembly- creates/sends pressurized to active suspension components. When the air suspension starts leaking, the compressor/pump starts working harder to try to keep the system inflated. By the time air suspension leaks down completely, sitting the vehicle on its tires, the compressor will either have failed or be well on its way to full failure. Buying replacement struts and taking the time to install them only to find out the compressor still needs to be replaced can be very frustrating, time-consuming, and expensive.
1997-2002 Ford Expedition (4WD) Torsion Bar- Adjustable horizontal bar on the front of the vehicle that holds the vehicle off the ground.
1997-2002 Ford Expedition (4WD) Dryer- prevents moisture build-up inside of air suspension parts.
1997-2002 Ford Expedition (4WD) Suspension Control Module- a computer which is responsible for the operations of the air suspension system and maintaining the vehicles correct ride height.