Control angles of rotation
The design of the front axle and steering provides the opportunity to achieve an optimal compromise of all factors that influence the rolling of the wheels on the road surface when driving straight and in the entire range of the wheel rotation angle. If the recommended geometric values are not maintained, the wheels partially slip during rolling - they are scraped off the road surface. The result is excessive and rapid wear of the tires. Some wheel installation values, of course, have a tolerance.
A similar situation is observed with the rear axle, with the only difference being that the wheels are not able to turn.
A simultaneous condition is also harmony in the installation of the front and rear axles.
Both must be mutually parallel and at the same time perpendicular to the longitudinal axis of the car and this axis must divide the wheel tracks in half.
Taking into account the maximum simplification of maintenance, a very small number of geometric elements can be adjusted.
From the main geometric values of the front axle (camber of wheels, tilt of the pivot of the steering knuckle sideways, tilt of the pivot of the steering knuckle back, wheel convergence, limit angle of rotation and control angle of rotation of the controlled wheels) adjustment can only affect the wheel alignment and the control angle of rotation of the steering wheels.
The rear axle wheel alignment values are set by design and none of them are adjustable.
The front axle wheel alignment can be influenced by shortening or lengthening the steering rods. It is necessary to warn here that the correction must be carried out simultaneously by changing the length of both rods, namely each by half the required value. The control must be symmetrical. For information, we add that the relative length of the steering rods is determined by measuring the length of the threaded part between the end of the thread and the lock nut of the ball joint. This size must be the same for both rods.
For practical use, it is important to know that shortening or lengthening a tie rod by 1 mm, achieved by rotating one tie rod by 360°, changes the wheel alignment by approximately 0°15' for each wheel.
The symmetry of the steering is necessary to ensure that the turning angles of the steered wheels are maintained during the process of turning the wheels from one extreme position to another.
In any position of the steering wheel rotation, their installation must be such that the radial planes of the wheels are perpendicular to the straight lines passing through the wheel axes and the point of rotation of the vehicle.
Measuring geometry is a very responsible job that requires skilled skills, precision, care and good measuring equipment. Therefore, it is recommended to carry out geometry control at a ŠKODA service center.