Suspension and Steering Systems
Components and operation
Suspension carries the vehicle, isolates road input and keeps the tyre contact patch stable. Springs support load, dampers control oscillation, and anti-roll bars limit body roll. MacPherson struts combine spring, damper and location in one unit. Ball joints, control arm bushings, tie rod ends, wheel bearings and steering racks are wear items; check them with the vehicle loaded and unloaded, and by feel for play and noise. Electric power steering replaces hydraulic assistance and adds a torque sensor and motor, so faults may need scan-tool calibration.
Wheel alignment
The three primary angles are camber (lean of the wheel from vertical, negative meaning the top leans in), caster (steering axis tilt, giving self-centring and stability) and toe (difference in track between front and rear of the wheels, toe-in means they point toward each other). Thrust angle and steering angle sensor position affect whether the vehicle tracks straight. Tyre wear patterns reveal the cause: both edges worn suggests under-inflation, centre wear over-inflation, one-sided wear a camber fault, feathered edges a toe fault.
Wheels and tyres
Balance, runout, tyre size, load rating and TPMS all affect behaviour. Rubber bushings must be tightened with the vehicle at normal ride height, or they preload and fail early.
Rule of thumb: set tyre pressures cold and check alignment after any suspension or steering component replacement. Traps include mixing up positive and negative camber, assuming a pull is always alignment when a dragging brake or mismatched tyre can cause it, and torquing suspension bushes with the vehicle hanging.