A Process of Elimination
A few basic concepts must be understood before attempting to diagnose a vibration concern. As in any diagnostic process, information must be gathered and deciphered, and a correction then performed based on the results.
Information concerning the concern is first gathered from the customer. Road testing and inspection of the vehicle is then performed in a manner intended to systematically eliminate different parts of the vehicle. The information gathered from the testing and inspection in turn supplements the information received from the customer.
By concentrating repair efforts on the areas that have NOT been eliminated, repairs can be made more quickly and effectively. An example of the process of elimination in use: A vehicle coming into a dealership has a customer concern of a vibration at 48 km (30 mph). During the road test, the technician discovers that the same vibration can be felt, when the vehicle is stopped and the engine speed is increased to about 1200 RPM.
The logical approach based on this information, would be to concentrate on components which are related to the engine. The tires, wheels, and the driveline have already been eliminated as a possible cause, because they are not rotating when the vehicle is standing still.
Duplicate the Condition
All vehicles produce vibrations. Some vibrations are normal, some are not. Some vibrations can be repaired, others cannot. You must be able to experience or duplicate exactly what is displeasing the customer. You must be able to evaluate the problem (the vibration and the cause of the vibration) under changing conditions. Otherwise, there is no way to know for sure that you are fixing what the customer would like fixed.
The symptoms and characteristics of a noise or vibration are also important information:
| • | What does the vibration feel like? |
| • | Does the vibration make noise? If so, what does the noise sound like? |
Different types of noise and vibration have particular characteristics that will help determine the cause of the condition and the best way to correct the condition. This is the reason for duplicating the vibration.
To begin the first steps into diagnosing the vibration concern, refer to Road Test .
General Vibration Principles
For general information on vibration theory, vibration terminology and the electronic vibration analyzer (EVA), refer to General Description .
