General information
The rear wheel alignment angles are set at the factory and are not included in the controlled parameters.
Wheel alignment angles of a car
The front wheel alignment angles determine the geometry of the latter's position relative to the vehicle's suspension and the road surface. Violation of this geometry adjustment leads to decreased vehicle controllability and increased tire wear. The front wheel alignment angles subject to control include coasting (longitudinal tilt angle of the wheel pivot axis), camber, wheel alignment and toe-in (see illustration Wheel alignment angles of a car). Only one of the parameters is subject to adjustment - toe-in. Other parameters should be checked on a regular basis to assess the degree of wear of the suspension and steering components.
Wheel alignment is one of those procedures that require particularly precise measurements, and for high-quality performance it is necessary to have special, rather bulky and expensive equipment. It is best to entrust this work to professional mechanics at a car service center. Below, for general understanding, are definitions of each of the controlled wheel alignment angles of a car, knowledge of which will facilitate communication between the car owner and the car service personnel.
The angle of longitudinal inclination of the wheel rotation axis (coast) is 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. The adjustment of the front wheel runout is carried out by selecting spacer washers placed under the suspension push rods.
Collapse is 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. 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 and allows for compensation for changes in the suspension geometry when turning and when the car is moving on uneven road surfaces. The models of cars in question do not have the ability to adjust the camber.
The angle of the transverse inclination of the wheel rotation axis this is called the angle between the axis of inclination of the steering knuckle and the vertical plane parallel to the vehicle's DP, drawn through the wheel attachment point.
Due to the camber and the angle of the transverse tilt of the wheel pivot axis, 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 "rolling shoulder" that makes it easier to control the car and reduces the effect of the transmission of impacts of the wheels on the unevenness of the road surface to the steering.
Convergence is the amount of convergence of the front edges of the car wheels. Such a violation of the parallelism of the wheel installation helps to minimize tread wear due to skidding when turning. At 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). Adjustment of the front wheel toe-in 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 adjusting cam bolt is screwed into the inner end of the rear suspension control arm. Violation of the toe-in adjustment leads to accelerated wear of the tire treads due to their slippage on the road surface.
Conditions for checking wheel alignment angles
Checking the vehicle's installation angles requires an inspection pit or a special measuring lift. When taking measurements, the following conditions must be met:
- The air pressure in the tires meets the requirements Specifications;
- The front wheels are set in a straight-ahead position;
- The car is not loaded, the fuel tank is full;
- The car's suspension is very compressed;
- The steering gear is adjusted correctly;
- The play in the articulation of the suspension components and steering gear does not exceed the permissible ranges;
- The tread depth of the tires on the same axle is the same.
All parameters, except for toe-in, are set during vehicle production and are not subject to adjustment. Unless the vehicle has been in a serious accident, the wheel alignment angles should be maintained throughout the vehicle's service life. If you are not sure that the parameters that are not subject to adjustment are correctly determined, seek help from specialists.
At home, toe-in can be measured in two ways. The first involves measuring the distances between the front inner edges of the wheel rims with a suitable measuring device. The second method requires a special plate. By placing the plate perpendicular to the wheel and rotating it, you can detect the deviation of the wheels. The measuring device or plate can be purchased in specialized stores.
If the check reveals that the toe-in needs to be adjusted, loosen the end cap locknuts.
1. Turn the steering wheel all the way to the left and accurately count the visible number of threads on the right steering rod. Then turn the steering wheel all the way to the right and count the visible number of threads on the left rod. If the two numbers match, you will need to loosen or tighten both ends by the same number of turns during subsequent adjustment. If the results obtained differ from each other, you will need to compensate for the difference during subsequent adjustment. After adjustment, both rods should have the same number of free threads.
2. After completing the adjustment, tighten the lock nuts - since the rods have rotated, the protective covers of the steering mechanism will most likely be deformed and you should loosen the clamps that secure them and make the appropriate corrections.
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