Suspension, Steering, and Wheel Alignment Servicing
Domain 7 covers the geometry and components that keep the tyre contact patch correct: steering linkage, ball joints, springs, struts, bearings, and the four alignment angles.
Core rules
- Camber is the inward or outward tilt of the wheel seen from the front; caster is the steering-axis tilt seen from the side, with positive caster giving straight-line stability and self-centring.
- Toe is the difference between the front and rear of the tyres; total toe is set last, with the steering wheel centred and the tie rods adjusted evenly.
- Thrust angle is the rear axle's direction relative to the vehicle centreline; a non-zero thrust angle makes the car dog-track and pull.
- Check ride height, tyre pressures and wheel bearing play before aligning; align on a level floor at kerb weight.
- Diagnose play correctly: rocking at 12 and 6 o'clock suggests bearing or ball joint, at 3 and 9 o'clock tie rod ends; load the joint before judging.
- Torque rubber-bushed fasteners with the vehicle at normal ride height, otherwise the bushings tear.
Worked example
A car pulls right. Alignment shows front camber left +0.4°, right −0.6° (specification 0 ± 0.5°). Reasoning: each side is inside tolerance, but cross-camber is 1.0°, and that difference creates a lateral force toward the more negative side, the right. Toe is within specification and rarely produces a steady pull; caster spread also needs checking. Before adjusting, swap the front wheels left to right: if the pull reverses, tyre conicity was the cause; if it stays, set camber, re-check caster, then road test.
Traps
- Setting toe without centring the steering wheel, leaving it off-centre.
- Aligning a car with worn tie rods, collapsed strut mounts or wrong ride height.
- Torquing bushings with the suspension hanging.
- Reading tyre cupping as alignment only - it usually means balance or dampers.