For 1990-2009 cars

This section describes the techniques and procedures for correcting the following types of vibrations:

• | Tire and wheel shake

• | Launch shudder

• | Exhaust moan

• | Engine firing frequency

• | Drive line vibration

### Identifying the Concern

The first step in diagnosing a vibration concern is to identify the exact vibration that concerns the customer.

Sometimes the vibration can be duplicated at a given speed. Other vibrations may not be as evident and may require questioning the customer carefully. Perform a road test with the customer in the vehicle in order to determine the specific vibration complaint.

Ask the following questions when attempting to identify a vibration complaint:

• | At what speed is the vibration the worst?

• | Can the customer feel the vibration? If so, where?

• | Can the customer hear the vibration?

• | Does the engine or the vehicle load affect the vibration?

• | Does the vibration occur in more than one gear range?

• | When did the vibration first appear?

The answers to these questions will help in duplicating and diagnosing the vibration.

If you suspect that the vibration is normal, compare the vibration with a vehicle that is equipped in the same way, including the following factors:

• | Body style

• | Engine option

• | Engine driven accessories

• | Transmission type

• | Tire size

• | Suspension performance type

• | Axle ratio

Important: Do NOT attempt to repair a normal condition, or the customer will probably be convinced that the vehicle has a problem. Customer satisfaction becomes extremely difficult after this point.

If necessary, ride with the customer. Make the comparison with the customer present and explain the situation.

### Duplicate the Condition

All vehicles produce vibrations. Some vibrations are normal, while others are not. Some vibrations can be repaired, some cannot. Duplicate or experience the customer's complaint. Evaluate the vibration and the cause of the vibration under changing conditions. Otherwise, you cannot know for certain that you are fixing what the customer would like fixed.

The symptoms and characteristics of a noise or vibration are also important information. Ask yourself the following questions before you begin:

• | What does the vibration feel like?

• | Does the vibration make noise? If so, what does the vibration sound like?

Different types of noise and vibration have particular characteristics. These characteristics will help determine the cause of the condition and the best way to correct the condition.

### A Process of Elimination

You must understand a few basic concepts before attempting to diagnose a vibration. As in any diagnostic process, you must perform the following steps:

• | Gather the information

• | Decipher the information

• | Make your correction based on the results

Road test the vehicle and inspect the vehicle in a manner which systematically eliminates different components. This process supplements the information which you have received from the customer concerning the complaint. Concentrating efforts on the areas that have not been eliminated will make repairs faster and more effective.