Collapse is the angle of the wheel plane relative to the vertical. If the wheels are tilted with their upper edges outward, the camber is called positive, and vice versa. The camber value 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 for compensation for changes in the suspension geometry that occur when turning and when the car is moving on an uneven road surface.
Convergence (convergence) is the amount of convergence of the front edges of the car wheels. This violation of the parallelism of the wheels helps to minimize tread wear by preventing skidding when turning. With zero toe-in, the distance between the front edges of the wheels is equal to the distance between their rear edges. Normal toe-in usually does not exceed fractions of an inch (1 inch = 2.54 cm). Violation of the toe-in adjustment leads to accelerated wear of the tire treads due to their slipping on the road surface.
Run-out it's called kingpin/wheel pivot angle, i.e., the angle of deviation of a given axis from the vertical in the plane of the wheel disk. If the steering axis/kingpin is tilted back, the runout is called positive, and vice versa.
Note: By analogy, the angle of transverse inclination of the wheel's pivot axis is called the angle of deviation of the imaginary kingpin from the vertical in a plane perpendicular to the plane of symmetry of the car.
Size maximum turning angles of the front wheels of the car should be reduced when increasing the size of the latter. The distance from the edge of the tire of the wheel turned to the stop to the longitudinal arm of the suspension should be about 2 cm, otherwise a corresponding adjustment is necessary (see Section Checking and adjusting the front wheel turning angle limits).
A general check of the suspension geometry is performed on a special stand in a specialized workshop.
Conditions for checking wheel alignment angles
Checking the vehicle's installation angles requires a specially equipped overpass. Before starting the check, make sure that the following conditions are met:
[Material borrowed from an online resource: mercedesman]
- The air pressure in the tires corresponds to the nominal;
- The front wheels are mounted in a straight line;
- The car is not loaded, the fuel tank is full;
- The vehicle's suspension elements are forced down;
- The steering gear is adjusted correctly;
- Play in the steering rod ends and suspension ball joints does not exceed the permissible limits;
- The tread depth of tires mounted on wheels of the same axle is the same.