Steering, Suspension and Wheel Alignment
Geometry and ride control
Candidates must know steering systems (rack-and-pinion, recirculating ball), suspension types (MacPherson strut, double wishbone, live axle with leaf springs), and wheel alignment angles: camber, caster, toe, and kingpin inclination. Camber is the inward or outward tilt of the wheel viewed from the front; excessive camber wears one side of the tyre. Caster is the forward or rearward tilt of the steering axis and affects straight-line stability and self-centring; it does not normally cause tyre wear. Toe is the difference between front and rear of the tyres; incorrect toe causes feathered edge wear. Ackermann geometry allows inner and outer front wheels to follow different radii in a turn.
Traps in questions
A common trap is blaming caster for uneven tyre wear. Another is confusing positive camber with positive caster. Questions may ask about wheel balance versus alignment: imbalance causes vibration at speed, while misalignment causes wear and pull. Do not forget that worn tie-rod ends, ball joints, and strut mounts must be repaired before alignment. Tyre pressure differences can cause a pull and mimic alignment faults.
Rule of thumb
Set tyre pressures and check for play before measuring alignment; align only after suspension and steering components are sound.
Worked example: a tyre shows feathered edges across the tread. This indicates incorrect toe. Adjust toe to specification after checking that the steering rack and tie rods are not worn.