While driving at a certain speed, the steering wheel chatters towards the direction of rotation of the steering wheel. When a car steering wheel vibrates and the vibration is towards the direction of rotation of the steering wheel, this steering problem is called shimmy. Steering shimmy is defined as the vibration in the rotational direction of the steering wheel when the vehicle is running at a certain speed.
You can check if your car is suffering from steering wheel shimmy by accelerating your car slowly to 100 km/h and maintain that speed for a short period of time and feel the steering vibration by softly touching the steering wheel with your fingers. Be sure not to make a sudden acceleration or full braking for safety reasons.
During vehicle operation, the tire rotates. As the tire rotates, there is constant tire flexing and deflection in response to vehicle speed and load. Uneven tread rubber thickness and/or poor carcass and cord connection will produce irregular tire deflection resulting in shimmy, shaking, abnormal noise, and other vibrations. This will occur even if the vehicle load and speed are constant. Irregular tire deflection (hardness and rigidity changes) is called force variation. Force variation affects the upper and lower tire areas, the tire sides, and the leading and trailing edges of the tire/road surface contact area.
Wheel balancers are used to adjust the balance of individual wheels. There are two types of wheel balancers. The off-car wheel balancer requires the removal of the wheel from the vehicle. The on-car wheel balancer does not. The on-car balancer supports the vehicle axle or hub during the balancing procedure, and can only balance the tire staticaly. It is, therefore, recommended for diagnoses of driveline vibration problems only.
Steering Wheel Shakes When Braking
If you run into a problem of steering wheel shakes when braking there are two possible reasons, first is a warped front disc and the second is a loose or worn out front wheel bearing.
Read more: Steering Wheel Shakes When Braking
