Steering and Suspension Systems
Angles, geometry, and wear patterns
Alignment and geometry questions reward understanding causes. Camber is the inward or outward tilt of the wheel viewed from the front: too much negative camber feathers the inside edge of the tire, too much positive the outside. Caster is the fore-aft tilt of the steering axis; positive caster (top rearward) improves straight-line stability and steering return. Toe is the difference between front and rear of the tires measured across the vehicle, and incorrect toe produces feathered tread scrub and is the fastest tire killer. Thrust angle describes the rear axle's direction relative to the vehicle centreline; a mis-set rear axle makes the steering wheel off-centre and causes dog-tracking.
SAI and included angle help identify bent components - a bent knuckle or strut changes included angle even when camber looks reasonable. Always inspect before aligning: tire pressures and sizes, ride height, ball joint play, tie rod ends, control arm bushings, wheel bearing play, and steering rack mounts. Set rear adjustments first, then front camber and caster, then toe last. Some vehicles require weights or a specific fuel load during alignment.
Modern systems add electric power steering with torque sensors and steering angle sensors that must be reset or calibrated after alignment or battery service. TPMS sensors need relearning after wheel swaps.
Traps: diagnosing a pull as alignment when a dragging brake or radial tire pull is the cause; checking ball joints without loading the suspension correctly; ignoring tire wear patterns.
Worked example: total toe specification is 0.20° and the left front reads 0.15°. Set the right front to 0.05° so the sum matches, then centre the steering wheel and verify thrust angle.