Rear Suspension: Description

The rear suspension is a coil spring type system. It supports and links the rear axle to the frame with one upper control arm and two lower control arms. The two coil springs are of the variable rate, wire type. The upper spring coils are designed to contact each other when the vehicle is loaded. This shortens the spring to increase the rate and provide a firmer ride. When the vehicle is unloaded, the upper coils do not contact. This provides a lower rate and a softer ride. The small diameter upper spring is installed in the insulator on the frame. Both springs are matched in regard to the load capacity rate. If one spring is replaced, the replacement spring must match the capacity of the other spring.

The upper control arm locates the rear axle laterally in the vehicle and reacts to the body movement in relation to the rear axle. See Fig 1 . It also allows the vehicle to react to the braking and accelerating forces applied to the rear axle. The upper control arm is attached to the body at two points. It is attached to the axle at one point. The bushing at the rear axle attachment has a cam type bushing inside. By rotating the cam, the rear axle pinion angle is adjusted.

The lower control arms locate the rear axle in the vehicle and allow the vehicle to react to the braking and acceleration forces applied to the rear axle. They also provide a seat for the springs to support the vehicle weight. All rear suspension bushings are serviceable (both upper and lower control arms).

The low pressure gas shock absorbers are of direct, double-acting type. They provide a continuous dampening effect both on compression and rebound. These shock absorbers are of telescopic design with rubber bushings at the mounting points for quiet operation. The low pressure gas shock absorbers are sealed and charged with nitrogen gas to reduce shock absorber fade and improve vehicle ride. They are non-adjustable units and must be replaced as complete assemblies.

Jounce travel is controlled by jounce bumpers mounted on the rear axle tube. The bumpers are in contact with the vehicle frame rails when the suspension is in the jounce mode. Standard wagons and vans are equipped with two jounce bumpers. Optional payload wagons and vans are equipped with four jounce bumpers.