Correct wheel alignment is essential for stable steering, predictable handling and even tyre wear. The front suspension used on Holden HK, HT and HG models relies on several steering geometry angles that determine how the front wheels contact the road and respond to steering input. These angles include caster, camber, toe-in and steering axis inclination.
If any of these angles move outside their correct range the vehicle may develop steering problems such as wandering, pulling to one side, uneven tyre wear or poor directional stability. Understanding these alignment angles and how they affect vehicle behaviour is essential when diagnosing suspension and steering issues.
Caster
Caster is the angle of the steering axis when viewed from the side of the vehicle. Positive caster occurs when the upper steering pivot is positioned behind the lower pivot point. This geometry causes the wheels to naturally return to the straight-ahead position after a turn.
Positive caster improves straight line stability and directional control at higher speeds. However, excessive caster can increase steering effort and may cause heavier steering feel when manoeuvring at low speeds.
If caster settings differ between the left and right sides of the vehicle the car may pull toward the side with the lowest caster setting.
Camber
Camber refers to the inward or outward tilt of the front wheels when viewed from the front of the vehicle.
Positive camber means the top of the wheel leans outward. Negative camber means the top of the wheel leans inward. Correct camber ensures that the tyre tread sits squarely on the road surface.
Incorrect camber can lead to several problems including:
• Hard steering
• Vehicle wandering or instability
• Uneven tyre wear on the inner or outer edges of the tyres
Maintaining correct camber ensures even tyre contact with the road and improves overall handling.
Toe-In
Toe-in describes the difference between the distance at the front of the tyres compared with the distance at the rear when the wheels are pointing straight ahead.
When correctly adjusted the front of the tyres are slightly closer together than the rear. This small amount of toe-in compensates for suspension movement and tyre deflection that occurs while driving.
Incorrect toe settings can cause:
• Rapid tyre wear
• Steering instability
• Excessive tyre squeal during turns
Toe-in is one of the most critical alignment settings because even small errors can quickly lead to tyre damage.
Steering Axis Inclination
Steering axis inclination is the angle between the steering pivot axis and a vertical line through the centre of the wheel. This angle works together with camber to produce a self-centering action in the steering system.
Correct steering axis inclination helps reduce steering effort and improves stability when the vehicle is cornering.
If this angle becomes incorrect it is usually caused by worn or damaged suspension components rather than an adjustment issue.
Preliminary Inspection Before Alignment
Before attempting to check or adjust wheel alignment the suspension and steering components should be inspected carefully. Alignment adjustments will not be effective if worn parts are present.
Important inspection points include:
• Ensure tyres are correctly inflated
• Inspect steering ball joints and linkage for wear
• Check suspension bushings and control arms
• Inspect shock absorber mountings
• Check wheel bearings for excessive play
• Ensure steering gear and mounting points are secure
Alignment should always be carried out with the vehicle at normal operating height and with the suspension settled.
Caster and Camber Adjustment
On HK, HT and HG models the caster and camber settings are adjusted using shims fitted between the upper control arm shaft and the front crossmember.
Different shim thicknesses are used to change the alignment angles.
Typical shim thicknesses include:
• 0.030 inch
• 0.059 inch
• 0.120 inch
Adding or removing shims alters the position of the upper control arm which changes both caster and camber angles.
General adjustment principles include:
• Adding shims to both mounting bolts mainly changes camber
• Adding shims to the rear bolt increases caster
• Removing shims reduces caster
After making adjustments the mounting bolts must be tightened securely and the alignment measurements rechecked.
Toe-In Adjustment
Toe-in is adjusted by altering the effective length of the steering tie rods.
Adjustment is made by loosening the lock nuts and rotating the tie rod adjusting sleeve until the correct toe setting is obtained. Once the correct measurement is reached the lock nuts are tightened securely to prevent the setting from changing.
Toe-in should always be checked after caster and camber adjustments have been completed.
Checking Steering Geometry
Steering geometry should also be checked to ensure the wheels follow the correct path when turning. This check confirms that the steering arms and linkage are correctly aligned and have not been bent or damaged.
During this test the wheels are turned to a specified angle and the corresponding angle of the opposite wheel is measured. Correct geometry ensures smooth turning and proper tyre tracking through corners.
Importance of Correct Alignment
Proper wheel alignment ensures that the vehicle tracks straight, steering effort remains predictable and tyres wear evenly. Because the alignment angles interact with each other, adjustments should always be carried out carefully and measured accurately.
While this guide helps identify common problems, the Holden workshop manuals available from Car Manuals Direct include the original specifications, adjustment settings and repair procedures used by Holden mechanics when these vehicles were new.