General information
The rear wheel alignment angles are set at the factory and are not among the parameters under control.
Vehicle wheel alignment
The angles of the front wheels determine the geometry of the position of the latter relative to the suspension of the car and the road surface. Violation of the adjustment of this geometry leads to a decrease in the controllability of the car and an increase in the rate of tire wear. The number of angles of installation of the front wheels of the car to be controlled includes run-out (the angle of the longitudinal inclination of the axis of rotation of the wheel), camber, lateral inclination of the wheel axis and convergence (see illustration Vehicle wheel alignment). Only one of the parameters is subject to adjustment - convergence. Other parameters should be checked on a regular basis to assess the degree of wear of the suspension and steering components.
Adjusting the wheel alignment angles is one of the procedures requiring special measurement accuracy, for the high-quality implementation of which it is necessary to have special, rather bulky and expensive equipment. It would be best to entrust this work to professional car service mechanics. Below, for a general understanding, are the definitions of each of the controlled car wheel alignment angles, the knowledge of which will facilitate the communication of the car owner with the car service personnel.
The angle of the longitudinal inclination of the axis of rotation of the wheel (coasting) called the angle of deviation from the vertical of the axis of rotation of the wheel in the plane of the latter. If the axis of rotation is tilted back (the lower part of the axle is pushed forward), the runout is called positive, and vice versa. Adjustment of the run-out of the front wheels is carried out by selecting distance washers placed under the push rods of the suspension.
collapse called the angle of inclination of the plane of the wheels relative to the vertical. If the wheels are tilted with their upper edges outward, the camber is called positive, and vice versa. Camber is measured in degrees. The correct camber adjustment determines the size and position of the tread contact patch with the road and allows you to compensate for changes in suspension geometry during cornering and when driving on uneven road surfaces. On the considered models of cars, the possibility of adjusting the camber is not provided.
Tilt angle of the wheel axis this is called the angle between the axis of inclination of the steering knuckle and a vertical plane parallel to the DP of the car, drawn through the wheel attachment point.
Due to the camber and the angle of the transverse inclination of the axis of rotation of the wheel, the points of contact of the wheels with the road are located closer to the axis of the steering knuckle, which supports the so-called «running shoulder» facilitating driving and reducing the effect of transmission of wheel impacts on uneven surfaces to the steering.
Convergence called the amount of convergence to each other of the front edges of the wheels of the car. Such a violation of the parallelism of the wheels allows minimizing tread wear due to skidding when making turns. At zero convergence, the distance between the front edges of the wheels is equal to the distance between their rear edges. Normal convergence is usually less than a fraction of an inch (1 inch = 2.54 cm). Adjustment of the convergence of the front wheels is carried out by adjusting the length of the steering rods by changing the position of their tips. To adjust the toe-in of the rear wheels, a special adjustment cam bolt is provided, screwed into the inner end of the rear suspension control arm. Violation of the adjustment of convergence leads to accelerated wear of the tire tread due to their slippage on the road surface.
Conditions for checking wheel alignment
Checking the installation angles of the car requires a viewing hole or a special measuring lift. When performing a measurement, the following conditions must be met:
- Tire pressure meets the requirements Specifications;
- The front wheels are set in a straight position;
- The car is not loaded, the fuel tank is full;
- The suspension of the car is strongly compressed;
- The steering gear is correctly adjusted;
- The backlash of the articulation of the suspension and steering components does not go beyond the permissible ranges;
- The tread depth of tires of one axle is the same.
All parameters, except for convergence, are set during the production of the car and are not subject to adjustment. Unless the vehicle has been in a serious accident, wheel alignment must be maintained throughout the life of the vehicle. In the absence of confidence in the correctness of the definition of parameters not subject to adjustment, seek help from specialists.
At home, convergence can be measured in two ways. In the first, the distances between the front inner edges of the wheel rims are measured with a suitable meter. The second method will require a special plate. By setting the plate perpendicular to the wheel and rotating it, wheel deflection can be detected. A meter or plate can be purchased from specialized stores.
If the test reveals that the toe-in needs adjustment, loosen the tip locknuts.
1. Turn the steering wheel all the way to the left and accurately count the visible number of threads on the right tie rod. After that, turn the steering wheel all the way to the right and count the visible number of threads on the left pull. If the two numbers match, subsequent adjustments will require both lugs to be unscrewed or screwed in by the same number of turns. If the results obtained differ from each other, the subsequent adjustment must compensate for the difference. After adjustment, both rods must have the same number of loose threads.
2. Having finished the adjustment, tighten the locknuts - since the rods rotated, the protective covers of the steering mechanism will most likely be deformed and the collars of their fastening should be loosened and the appropriate corrections should be made.
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