This vehicle has a gas pressurized MacPherson strut type front suspension design. (Scheme 1)
Scheme 1
The front suspension includes the following components
- Hub
- Bearing
- Lower control arm
- Stabilizer bar
- Steering knuckle
- Strut assembly
For more information on the description and operation of an individual component, refer to the applicable component.
The front suspension allows each front wheel on a vehicle to adapt to different road surfaces and conditions without greatly affecting the opposite wheel and the ability to control the vehicle. Each side of the front suspension is allowed to pivot so the vehicle can be steered in the direction preferred.
When a vehicle strikes a bump, the force is transferred through the hub, bearing, and knuckle, into the strut assembly to absorb the force and dampen it. During steering maneuvers, the strut assembly (through a pivot bearing in the upper strut mount) and steering knuckle (through the lower ball joint mounted on the lower control arm) turn as an assembly.
DESCRIPTION
The wheel bearing and hub are pressed into the steering knuckle. (Refer to DESCRIPTION - STEERING KNUCKLE ).
OPERATION
The wheel bearing and hub are pressed into the steering knuckle. (Refer to OPERATION - STEERING KNUCKLE ).
DESCRIPTION - STEERING KNUCKLE
The steering knuckle is a single casting with legs machined for attachment to the front strut assembly on the top, lower control arm ball joint on the bottom, and steering linkage on the trailing end. (Scheme 1) The steering knuckle also has two machined abutments (rails) on the leading end casting to support and align the front disc brake caliper.
The knuckle supports the wheel bearing and hub. (Scheme 1) The wheel hub is pressed into a sealed-for-life wheel bearing that is pressed into the steering knuckle. A retainer plate also holds the bearing in place. The hub supports the driveshaft outer constant velocity (C/V) joint. Each is splined and meshes in the center of the hub. The outer C/V joint is retained to the hub using a nut. The nut is locked to the outer C/V stud shaft using a nut retainer and cotter pin.
The wheel bearing is a Unit 1 type cartridge bearing that requires no maintenance. The wheel bearing can be serviced separately from the hub.
The hub has five studs pressed into its flange.
OPERATION - STEERING KNUCKLE
The steering knuckle pivots with the strut assembly between the lower ball joint and the pivot bearing in the strut assembly. The steering gear outer tie rod end connects to the trailing end of each knuckle, allowing the vehicle to be steered.
The center of the knuckle supports the hub, wheel bearing and axle shaft.
The hub and wheel bearing work together. The wheel bearing has internal bearings that allow the hub to rotate with the driveshaft and the tire and wheel assembly. The hub's five studs mount the tire and wheel to the vehicle.
There is one lower control arm on each side of the vehicle. Each lower control arm is a stamped steel unit using rubber isolated pivot bushings to isolate it from the front suspension crossmember and frame of the vehicle. (Scheme 1) The rear bushing can be serviced separately.
The front of the lower control arm is bolted to the front crossmember using a bolt through the center of the rubber pivot bushing. The rear of the lower control arm is mounted to both the front crossmember and the frame rail of the vehicle using a thru-bolt. The thru-bolt goes through both the crossmember and rear lower control arm bushing, threading directly into the frame rail of the vehicle.
The left and right lower control arms are interconnected through a linked rubber isolated stabilizer bar.
The outboard end of each lower control arm connects to the steering knuckle using a ball joint.
The lower control arm connects to the steering knuckle through a ball joint mounted at the outboard end of the arm. (Scheme 1) The ball joint is pressed into the lower control arm and has a non-tapered stud with a notch for steering knuckle pinch bolt clearance. The ball joint stud is clamped and locked to the steering knuckle lower leg using a pinch bolt.
The ball joint is lubricated for life during the manufacturing process. Once lubricated for life, the grease fitting head is snapped off by the manufacturer. This is done to eliminate the possibility of lubrication later in the ball joints life thus damaging the non-vented ball joint seal boot.
The ball joint used on this vehicle is replaceable and, if found defective, can be serviced as a separate component of the lower control arm.
The stabilizer bar helps control vehicle body roll. Jounce and rebound movements affecting one wheel are partially transmitted to the opposite wheel of the vehicle to stabilize body roll.
The stabilizer bar interconnects both front lower control arms of the vehicle and is attached to the front suspension crossmember. (Scheme 1)
Attachment of the stabilizer bar to the front suspension crossmember is through 2 rubber-isolator cushion and retainers. (Scheme 1) The stabilizer bar attachment to the lower control arm is done by utilizing an isolated stabilizer bar link at each arm. All components of the stabilizer bar are serviceable.
DESCRIPTION - STRUT ASSEMBLY (FRONT)
There are two different design struts available on this vehicle. A standard strut and an adjustable strut which is used on vehicles equipped with the ACR performance package. Both struts share common style components except that the ACR strut has no external jounce bumper. It is internal.
A Macpherson type design strut assembly is used in place of the front suspension upper control arm and upper ball joint. (Scheme 1) The bottom of the strut mounts directly to the steering knuckle using 2 attaching bolts and nuts going through the strut clevis bracket and steering knuckle. The top of the strut mounts directly to the strut tower of the vehicle using the three threaded studs on the strut assemblies upper mount. During steering maneuvers, the strut assembly (through a pivot bearing in the upper strut mount) and steering knuckle (through the lower ball joint) turn as an assembly.
The strut assembly includes the following components
- Strut shaft retaining nut
- Upper mount (rubber isolated)
- Upper spring seat and bearing
- Dust shield
- Jounce bumper
- Coil spring
- Lower spring isolator
- Strut (damper)
Each component is serviced by removing the strut assembly from the vehicle and disassembling it.
The strut and front suspension of the vehicle is supported by coil springs positioned around the upper half of each strut. The springs are contained between the upper and the lower seats of the strut assembly.
Coil springs are rated separately for each corner or side of the vehicle depending on optional equipment and type of vehicle service. During service procedures of the strut assembly, if both springs are removed, mark the springs to ensure installation in its original position.
Note. If a coil spring requires replacement, be sure that it is replaced with a spring meeting the correct load rating for the vehicle and its specific options.
The adjustable ACR strut has a knob on the bottom. It is there to adjust the suspension firmness. Although the strut shaft is much thicker on ACR struts, the same upper mount and retaining nut can be used.
OPERATION - STRUT ASSEMBLY (FRONT)
The strut assembly cushions the ride of the vehicle, controlling vibration, jounce and rebound of the suspension.
The coil spring controls ride quality and maintains proper ride height.
The spring isolators isolate the coil spring at the top and bottom from coming into metal-to-metal contact with the upper mounting seat and the strut.
The jounce bumper limits suspension travel and metal-to-metal contact under full jounce condition.
The strut dampens jounce and rebound motions of the coil spring and suspension.