Front suspension (Description): Description and operation

Description

General

The front suspension comprises two dampers and coil springs, two radius arms, a Panhard rod and an anti-roll bar. The front axle provides the location points for the dampers, springs, radius arms and the Panhard rod.

The anti-roll bar assembly is an essential part of the front suspension. On vehicles without Active Cornering Enhancement (ACE) a conventional 'passive' anti-roll bar is fitted. On vehicles fitted with the ACE system, a thicker diameter anti-roll bar, known as a torsion bar, is used with an actuator at one end. FRONT SUSPENSION, DESCRIPTION AND OPERATION, Description - ACE.

The hydraulic dampers and coil springs provide springing for each front wheel. The long travel dampers, springs and radius arms provide maximum axle articulation and wheel travel for off-road driving. The front axle is controlled longitudinally by two forged steel radius arms and transversely by a Panhard rod.

Radius arms

Each radius arm is manufactured from forged steel. Two bushes are pressed into the forward end of the radius arm. The forward end of the radius arm is located in a fabricated bracket on the axle and secured through the bushes with two bolts and nuts. A bush is pressed into the rear of the radius arm which is also located in a fabricated bracket on each chassis longitudinal and secured through the bush with a bolt and nut.

The radius arms prevent longitudinal movement of the front axle and because of their length allow maximum axle articulation. The stiffness of the bushes in each radius arm also contributes to the vehicle roll stiffness.

Each radius arm has a notch on its lower edge which provides location for the vehicle jack.

Dampers

Two conventional telescopic dampers are used to control body/axle movement. A turret is located on a bracket welded to the chassis. The upper spring seat has four studs which pass through holes in the bracket and align with corresponding holes in the turret. Four nuts are screwed onto the studs and secure the turret and upper spring seat to the chassis.

A fabricated platform is welded to the axle. The platform has two captive nuts which provide for the attachment of the damper. A lower spring seat is located on the platform. Each spring seat is handed and has a bracket which secures the ABS sensor harness and the front brake hose.

Each damper is fitted with a bush at its upper end. The bush locates in the top of the turret and is secured with a cross bolt. The lower attachment point for the damper is also fitted with a bush. This bush has a spindle through its centre with a hole at each end. The spindle is seated on the lower spring seat and the axle platform and secured with two bolts. The coil spring is fitted in a compressed state between the upper and lower spring seats and assists the damper in controlling the body/axle movement. The upper and lower bushes are replaceable items.

Rubber bump stops are fitted to the chassis above each end of the axle. The bump stops are progressive in their compression and prevent the axle from contacting the chassis in the event of maximum suspension travel being reached. The bump stops revert to their original shape once the compression load has been removed from them.

The damper functions by restricting the flow of a hydraulic fluid through internal galleries within the damper body. A chromium plated rod moves axially within the damper. As the rod moves, its movement is limited by the flow of fluid through the galleries thus providing damping of undulations in the terrain. The damper rod is sealed at its exit point from the body to maintain fluid within the unit and prevent the ingress of dirt and moisture. The seal also acts as a wiper to keep the rod outer diameter clean. A plastic shroud protects the rod and slides over the body as the damper moves. The coil spring aids the damper to extend after being compressed and also aids the damping process.