Pic. 7.34. Wheel imbalance: a - in static; b - in dynamics
Wheel imbalance is felt by vibrations on the steering wheel or shaking of the front of the car. Both are especially pronounced at certain speeds. The reason for this is the uneven distribution of weight on the wheel. Distinguish wheel imbalance in statics and dynamics. An unbalance in statics occurs when a freely suspended spinning wheel constantly sways in the same place (pic. 7.34, a). Such a wheel will jump when moving, and the shock absorbers wear out faster.
An imbalance in dynamics manifests itself when the wheel is located at an angle to the axis (pic. 7.34b). At high speeds, it experiences vibrations and swaying.
Wheel imbalance
If an imbalance occurs, first of all, it is necessary to thoroughly wash the wheels, especially from the inside. Perhaps after that the cause will be eliminated.
Precise balancing is recommended, at least for the front wheels, as even the slightest imbalance is felt on the steering wheel. Balancing the rear wheels right on the car is dangerous. The differential may be damaged. Therefore, the wheels must be driven by the engine.
Therefore, wheels in statics and dynamics require balancing. There are two methods for this:
1. The wheel is removed from the car and screwed onto a special balancing stand. The wheel rotates on it, and the places of imbalance are indicated. Unbalance is equalized by attaching special balancing weights on the wheel.
2. Sometimes a more precise final balancing is applied. To do this, the front wheels already installed on the car are rotated at the required speed on the stand by means of a contact shaft driven by an electric motor. The places of imbalance shown are also leveled with weights. However, Mercedes considers this procedure redundant, since the wheels of the produced cars are very well centered.
Balancing is not an easy task. It is necessary to limit yourself to as few weights as possible, which may require repeated rearrangement. Tires with a runout of more than 1 mm in height and lateral runout of more than 1.6 mm are not amenable to final balancing. The same applies to tires with a damaged carcass, for example due to a high-speed collision with a curb or other obstacle.