System View

Front Suspension Component Layout

1. Damper top mounting – LH
2. Damper top mounting – RH
3. Upper wishbone
4. Upper wishbone bushes
5. Shims – castor angle adjustment
6. Shims – small – castor angle adjustment
7. Sway bar mounting bracket
8. Sway bar bush
9. Sway bar
10. Lower wishbone
11. Lower wishbone bushes
12. Sway bar drop link
13. Hub assembly
14. Upright
15. Shims – wheel sensor/camber angle
16. Shims – camber angle
17. Steering arm
18. Coil spring/damper unit

Rear Suspension Component Layout

1. Upper wishbone
2. Upper wishbone bushes
3. Lower wishbone bushes short with interleaf
4. Upper wishbone
5. Track control arm
6. Sway bar
7. Sway bar bushes
8. Sway bar bracket
9. Sway bar droplink
10. Hub assembly
11. Upright
12. Shims – wheel sensor/camber angle
13. Shims – camber angle
14. Carrier ball joint
15. Coil spring/damper unit
16. Lower wishbone bushes long with interleaf

Description

General

Front Suspension

The vehicle features fully independent front suspension and comprises of upper and lower wishbones of unequal length, concentric coil spring/telescopic damper units and a sway bar.

The shorter upper wishbone and the angled lower wishbone converge providing optimum road holding, cornering and handling characteristics. Both upper and lower wishbones are bolted directly to the chassis at the inboard ends, where rubber pivot bushes are fitted. This suspension type is very compact allowing all mounting points to be contained within a relatively small area of the chassis.

The upper and lower wishbones are connected via tapered ball joints to forged steel uprights. The uprights provide mounting for the wheel speed sensor assembly and a combined steering arm/upper ball joint carrier.

Concentric coil spring/telescopic damper units fit between the chassis and the outer ends of the lower wishbones.

A forward-mounted tubular steel sway bar is supported in chassis-mounted pivot bushes and is connected by short ball jointed drop links to the lower wishbones.

The uprights provide mountings for a wheel bearing and hub assembly, secured by three bolts and incorporating a wheel speed sensor. Each front road wheel is attached to the hub assembly using five bolts.

The suspension geometry is fully adjustable for castor, camber and toe.

Rear Suspension

The rear suspension system is fully independent and comprises of upper and lower unequal length wishbones, a track control arm, concentric coil spring/telescopic damper units and a sway bar.

The shorter upper wishbone and the angled lower wishbone converge providing optimum road holding, cornering and handling characteristics. Both upper and lower wishbones are bolted directly to the chassis at the inboard ends, where rubber pivot bushes are fitted. This suspension type is very compact allowing all mounting points to be contained within a relatively small area of the chassis.

The upper and lower wishbones are connected via tapered ball joints to forged steel uprights. The uprights provide mounting for the wheel speed sensor assembly and a combined steering arm/upper ball joint carrier.

The adjustable length, double ball jointed, track control arm, shares a subframe anchorage with the rear pivot of the lower wishbone and at its outboard end, is secured directly into a tapered hole in the hub carrier.

Concentric coil spring/telescopic damper units fit between the chassis and the outer ends of the lower wishbones.

A rearward-mounted tubular steel sway bar is supported in chassis-mounted pivot bushes and is connected by short ball jointed drop links to the lower wishbones.

The uprights provide mountings for a wheel bearing and hub assembly, which is secured by three bolts and incorporates a wheel speed sensor. Each front road wheel is attached to the hub assembly using five bolts.

The suspension geometry is fully adjustable for camber and toe.

Wishbones

Front Upper Wishbone

1. Castor shim washers
2. Upper wishbone bushes
3. Snubber (thrust) washer
4. Ball joint
5. Upper wishbone

The handed upper wishbones are anchored on their inner ends to the body tub. The two legs converge outboard to a ball joint housing which accommodates the swivel ball joint, the ball pin of which is secured directly to the steering arm which is itself secured to the front upright using two bolts.

Front Lower Wishbone

1. Lower wishbone bushes
2. Lower wishbone
3. Damper bracket
4. Ball joint

The handed lower wishbones are anchored on their inner ends to the body tub. The two legs converge outboard to a ball joint housing which accommodates the swivel ball joint, the ball pin of which is secured directly to the front upright.

The wishbone pivot bushes are rubber with a plastic flanged outer sleeve, a plain steel inner sleeve, and a plastic interleaf sleeve within the rubber bush to control the flexing characteristic.

Rear Upper Wishbone

1. Upper wishbone
2. Upper wishbone bushes
3. Ball joint

The handed upper wishbones attach to the chassis rear subframe, and converge outboard and forwards to a ball joint housing into which a swivel ball joint is pressed. The ball pin of this joint locates in a forged steel plinth which is itself secured to the rear upright using two bolts. The upper wishbone rear bush, identified by a blue paint mark, has no interleaf sleeve. The rear upper wishbones are handed components.

Rear Lower Wishbone

1. Lower wishbone bushes
2. Lower wishbone
3. Damper bracket
4. Ball joint

The handed lower wishbones are anchored at its front inboard end to the chassis rear crossmember via a steel bracket, and at its rear inboard end to the chassis rear subframe. The two legs converge outboard and rearwards to a ball joint housing which accommodates the swivel ball joint, the ball pin of which is secured directly to the rear upright.

The wishbone pivot bushes are rubber with a plastic flanged outer sleeve, a plain steel inner sleeve, and a plastic interleaf sleeve within the rubber bush to control the flexing characteristic.

Telescopic Damper Assemblies

1. Damper
2. Spring upper seat
3. Spring
4. Spring lower seat

The lower end of the damper units are mounted to the outer end of the lower wishbone assembly. The upper end is connected to the chassis via an upper mounting bracket. The damper is positioned so that the damping rod is fitted lowermost, helping to minimise unsprung weight.

The damper is of mono-tube construction and is filled with oil and gas. The upper and lower oil chambers are connected via small drillings. The shock absorber uses a piston travelling within a single tube in order to dissipate heat more rapidly, so ensuring that the shock absorbers are less susceptible to overheating on uneven roads.

The front and rear damper assemblies are of similar construction but differ in terms of dimensions and specification

Track Control Arms

1. Outer ball joint
2. Outer lock nut
3. Track control arm
4. Inner lock nut
5. Inner spherical joint

Rear wheel alignment is adjustable and is set by the track control arms, which consist of a steel rod with a machined LH thread on the inboard end and a RH thread on the outer end. The inboard end LH thread facilitates a spherical joint and lock nut. The spherical joint pivot bush is sandwiched into an integral box section on the rear subframe next to the rearmost lower arm pivot bolt pick up point. The rearmost lower wishbone bolt also secures the spherical joint to the subframe. The outboard end of the control arm rod facilitates a RH thread swivel joint and lock nut. The swivel joint pin sits in a taper in an integral mount in the upright assembly. The track control arms are not handed.

Sway Bars

Front

1. Clamp
2. Bush
3. Sway bar
4. Backing plate
5. Drop link

A steel 0.79 in (20 mm) diameter sway bar is mounted in pivot bushes onto the front face of the chassis, and is linked to the outboard ends of each lower front wishbone via short ball jointed drop links. The chassis mounted pivots use rubber bushes for noise isolation, which are retained by aluminum clamps. Washers welded to the bar bear against the inner sides of the bushes to provide lateral location of the bar.

NOTE: The contact areas of the sway bar, sway bar bushes and brackets require a light coating of any proprietary brand of high performance lithium based grease.

Rear

1. Backing plate
2. Sway bar
3. Bush
4. Clamp
5. Drop link

A steel 0.75 in (19 mm) diameter sway bar is mounted in pivot bushes onto the rear face of the rear subframe, and is linked to the outboard ends of each lower rear wishbone via short ball jointed drop links. The subframe mounted pivots use rubber bushes for noise isolation and are retained by steel clamps. Washers welded to the bar bear against the inner sides of the bushes to provide lateral location of the bar.

NOTE: The contact areas of the sway bar, sway bar bushes and brackets require a light coating of any proprietary brand of high performance lithium based grease.

Wheel Bearing and Hubs

1. Wheel bearing and hub
2. Wheel sensor fly lead
3. Drive flange

The sealed wheel bearings are contained in a steel housing secured to the hub carrier with three bolts. The double row, angular contact, ball bearing is retained in the outer housing and also onto the hub spigot. All four hub assemblies are common and incorporate a wheel sensor in the bearing unit, with a fly lead terminating in a connector secured by a camber shim bracket. If there is any discernible free play in the hub bearing, any roughness, tight spots or any signs of lubricant expulsion, the hub assembly should be replaced as there is no provision for adjustment.

Uprights

Front

1. Wheel sensor bracket
2. Camber angle shims
3. Steering arm
4. Upright

The front uprights are handed components comprising of a one-piece forged steel assembly with a single lower tapered mount to facilitate the lower wishbone ball joint. A forged steel steering arm is bolted to the suspension upright using two bolts. Camber angle adjustment shims are fitted between the upright and steering arm. The steering arm features two tapered holes; one to locate the upper wishbone ball joint and the other to locate the track rod end ball joint.

Rear

1. Wheel sensor bracket
2. Camber angle shims
3. Upper wishbone ball joint carrier
4. Upright

The rear uprights are handed components comprising of a one-piece forged steel assembly with two lower tapered mounts; one to facilitate the lower wishbone ball joint and the other for the outer track control arm ball joint. A forged steel carrier is bolted to the suspension upright using two bolts and a tapered hole in the carrier locates the upper wishbone ball joint. Camber angle adjustment shims are fitted between the upright and steering arm.

Wheels and Tires

Wheels

The standard wheels are constructed from cast aluminum alloy. Also available are directional forged aluminum wheels which further reduce the unsprung mass.

Tires

The tires feature a directional tread pattern improving handling and stability. As an option high performance, Yokohama AD048 tires are available. These tires have a slick tread pattern and improve performance in dry conditions.

NOTE: The tire size is displayed on the outer wall of each tire.

Tire Pressures

NOTE: The recommended tire pressures have been calculated to provide the best combination of vehicle range, tire life, ride comfort and road handling.

Suspension Geometry

General

Wheel alignment and suspension geometry is set at the factory on an alignment rig. Subsequent full geometry checks are required only after extensive front suspension repair, if uneven tire wear is evident or if steering difficulties are encountered.

WARNING: Geometry measurements must only be made using recommended equipment.

NOTE: Before any measurements or adjustments are made, it is essential to set the vehicle to its ‘mid-laden’ ride height.

1. Camber angle
2. Vertical
3. Center line of wheel

Wheel Alignment

Wheel alignment refers to the parallelism of the wheels when viewed from above. The wheels are said to 'toe-in' when the wheel paths converge ahead of the vehicle, and 'toe-out' when they diverge.

Front Alignment

For further information on adjusting front wheel alignment, refer to this information.

Rear Alignment

Rear wheel alignment is adjusted by slackening both ball joint lock nuts and turning the link rods as necessary to increase or decrease the effective length of the link. As a guide, lengthening the link rod by one 'flat' (one sixth of a turn) will increase toe-in by approximately 1 mm. After adjustment, tighten the two lock nuts to 55 Nm taking care to ensure that the ball joint sockets are aligned at 90° to each other to allow some free articulation.

Camber

Camber is the angle from vertical of the wheel when viewed from the front. Camber is negative when the wheel leans inwards at the top and positive when leaning outwards at the top. The correct camber achieves maximum efficiency of the tire under cornering loads.

The primary purpose of camber is to achieve the maximum efficiency of the tire under cornering loads and body roll (the specification is closely allied to a particular wheel/tire combination). The camber angle will change with suspension travel, becoming more negative on bump, and must be measured only at the specified ride height. Incorrect camber can result in handling deficiencies and excessive tire wear.

1. Wheel sensor bracket
2. Steering arm
3. Camber angle shims

Front camber geometry is set using an appropriate amount of 1 mm shims between the steering arm and upright assembly. Reducing the shim pack thickness will increase negative camber. Adding shims plates will reduce negative camber. A 1 mm shim will alter camber by approximately 0.25°.

1. Wheel sensor bracket
2. Camber shims
3. Ball joint carrier

Rear camber geometry is set using an appropriate amount of 1 mm shims between the carrier and upright assembly. Reducing the shim pack thickness will increase negative camber. Adding shims will reduce negative camber. A 1 mm shim will alter camber by approximately 0.25°.

Castor

Castor is the angle from vertical of the steering axis of the wheel when viewed from the side.

WARNING: Castor angle must only be checked or adjusted with the vehicle at the correct ride height. Refer to General for correct height this information. .

1. Top and bottom steering swivels
2. Castor angle

The main purpose of castor is to provide a natural straight running tendency of the front wheels when the vehicle moves forward and determines the degree of self-centering. Castor angles have a complex interaction with other steering geometries and, if unbalanced or outside of specification, can result in various stability and handling deficiencies.

Spacer washers are fitted ahead of, and behind, each of the top wishbone pivot bushes to allow the wishbone to be displaced forwards or backwards. This will effect a change of castor angle.

A rubber-faced snubber washer fitted against the rear face of the top wishbone front bush prevents metal to metal contact under extreme braking forces. The spacer washers may be re-distributed between the front and rear of each pivot bush but the snubber washer position and the total shim pack thickness of 1.5 mm (x4) at each pivot, including the snubber washer, MUST remain unchanged.

1. Castor shim washers
2. Snubber washer
3. Bonded plate
4. Bonded insert
5. Outer plastic sleeve
6. Inner steel sleeve

Shim washer distribution at the front bush of either wishbone must be copied at the rear bush of that wishbone. Transferring a 1.5 mm shim washer from ahead of, to behind, the pivot bushes, will reduce castor by approximately 0.4°. Transferring a 1.5 mm shim washer from behind, to ahead of, the pivot bushes will increase castor by approximately 0.4°.

WARNING: Shim washer distribution at the front bush of either wishbone must be duplicated at the rear bush of that wishbone.

NOTE: Ensure that the load spreading washers are correctly located beneath the bolt heads and nuts as shown above.

NOTE: Ensure that the pivot bolts are tightened only with the vehicle at ride height.

Operation

General

The suspension system serves two purposes:

• The first role is to contribute to the vehicle's handling and braking capabilities;
• The second is that the driver and passenger travel in a comfortable environment isolated from road noise, bumps and vibrations.

As the vehicle travels over a bump, the suspension moves upwards in turn compressing the coil spring/telescopic damper units. The compression of the springs stores the kinetic energy whilst the dampers control the vertical oscillation converting the kinetic energy of the suspension to heat energy. As the damper is compressed, oil is displaced by the piston from the lower to the upper chamber through the small drillings. The energy required to displace this oil provides the damping required. When the bump is passed, the spring will rebound and release the stored energy and the oil within the damper returns to the lower chamber.

To prevent foaming and bubbles in the oil, which degrades damper performance, the damper has a chamber of high pressure nitrogen above the oil chamber that suppresses the formation of bubbles.

Due to the nature of the unequal length wishbone suspension design, negative camber increases throughout the full travel of the suspension maintaining the tire contact on the road surface, increasing the cornering capacity and stability of the vehicle.