A car's steering and suspension geometry is defined by four basic settings, expressed in degrees, camber, castor, steering axis inclination, and toe setting, with only the front camber and front and rear wheel toe settings being adjustable on the models discussed. Camber refers to the angle of the front wheels from the vertical when viewed from the front or rear, with negative camber indicating inward tilt at the top. The front camber angle is adjusted by loosening the
Steering Knuckle-to-suspension strut mounting bolts and repositioning the hub carrier assemblies. Castor is the angle between the steering axis and a vertical line when viewed from the side, with positive castor indicating a rearward inclination at the top. Steering axis inclination is the angle between the vertical and an imaginary line drawn through the front suspension strut upper mounting and the control arm balljoint when viewed from the front. Toe setting measures the difference in distance between the front inside edges of the roadwheels and the diametrically opposite distance between the rear inside edges, with toe-in indicating inward pointing wheels and toe-out indicating outward splaying. The front wheel toe setting is adjusted by changing the length of the steering track rods, while the rear wheel toe setting is adjusted by altering the position of the rear suspension transverse arm-to-trailing arm mountings. Except for the front and rear toe settings and front camber angles, all other suspension and steering angles are set during manufacture, assuming they remain correct unless the vehicle has sustained accident damage. Special optical measuring equipment is required to accurately check and adjust the front and rear toe settings and front camber angles, and this work should be performed by a qualified dealer or expert, although many tyre-fitting centres can conduct at least a front wheel toe setting check for a nominal fee.