Wheel alignment angles — general information [Toyota Highlander XU20]

Wheel alignment angles determine the geometry of the wheels relative to the vehicle suspension and the road surface. Improper adjustment leads to reduced vehicle control and accelerated tire wear. Wheel alignment angles subject to control include camber, longitudinal tilt angle of the wheel steering axis, and toe-in (Fig. 25.1).



Wheel alignment is a very precise procedure, which requires special, rather bulky and expensive equipment to perform properly. Therefore, it is recommended to entrust this work to mechanics at properly equipped service stations. Below, for general understanding, are definitions of each of the car's wheel alignment angles, knowledge of which will facilitate communication between the car owner and the service station personnel.

Toe-in is the amount of convergence of the front edges of the wheels. The purpose of toe-in is to ensure that the wheels swing correctly. At zero toe-in, the distance between the front edges of the wheels is equal to the distance between their rear edges. In fact, toe-in is only a few millimeters. Adjusting the toe-in of the front wheels is done by adjusting the effective length of the steering rods (by changing the position of the tips on the steering rods). Rear wheel alignment is adjusted either using threaded adjusters on the rear wishbones or using cams on the inner ends of the wishbones (depending on the modal year). Improper alignment will result in accelerated wear or improper wear of the tire treads due to them slipping on the road surface.



Camber is the angle of the plane of the wheels relative to the vertical, when viewed from the front or rear of the car. If the upper edges of the wheels are tilted outward, the camber is called positive, if inward - negative. The camber angle is measured in degrees. Correct camber adjustment determines the size and position of the contact patch of the treads with the road surface and allows you to compensate for changes in the geometry of the suspension when cornering and when the car is moving on an uneven road surface.

The caster angle of the steering axis is the angle of the steering axis from the vertical. If the steering axis is tilted backwards, the caster angle is called positive. If forwards, it is called negative. Too little caster angle of the steering axis causes directional instability of the front of the car, while too much caster angle of the steering axis can cause increased effort on the steering wheel.