For 1990-2009 cars

### Differential Pinion Gear Bearings

Worn bearings tend to perform the following conditions:

• | Tend to aggravate and magnify the drive.

• | Tend to float and coast the noise.

• | Tend to result in heavy, irregular drive noise on constant acceleration and float.

• | Tend to result in an irregular noise on deceleration.

Rough bearings tend to perform the following conditions:

• | Tend to aggravate and magnify the drive.

• | Tend to float and coast the noise.

• | Tend to result in heavy, irregular drive noise on constant acceleration and float.

• | Tend to result in an irregular noise on deceleration.

Loose bearings tend to perform the following conditions:

• | Tend to aggravate and magnify the drive.

• | Tend to float and coast the noise.

• | Tend to result in heavy, irregular drive noise on constant acceleration and float.

• | Tend to result in an irregular noise on deceleration.

Rough or brinelled pinion bearings produce a continuous whine. This whine persists when coasting with the transmission in neutral even to a low speed. End play in the pinion gear bearings, even from natural wear, which permits the pinion to feed back into the ring gear, causes a noise on overrun or coast.

### Rear Wheel Bearings

Rough or pitted rear wheel bearings that are can be are responsible for a growling noise. The first impression of this growling noise could be suspected as a differential noise. The noise, however, does not vary on drive or coast. Additionally, the noise persists when coasting with the transmission in neutral. Frequently this noise can be readily identified by the sound being conveyed in an eccentric form. The noise can also be intermittent as the noise may fade for a short period. Perform the following steps to confirm the diagnosis of a rear wheel bearing noise:

1. Support the rear of the vehicle on safety stands.
2. Start the engine.
3. Disengage the traction control.
4. Raise the engine speed up to a fast idle with the top gear engaged.
5. Use a stethoscope to compare the noise of one bearing against the other.
6. Keep the volume adjustment down low to obtain the best results.
7. A difference in the noise of the rear wheel bearings can also by discerned by placing a steel-shafted screwdriver to the ear and in close proximity to each bearing in turn.

A noticeable difference in noise can usually be observed between a good and an excessively worn bearing.

### Differential Carrier Side Bearings

Side bearings produce a constant grinding noise of a slower nature than pinion bearings. Side bearing noise cannot be determined by the diagnosis procedure for rear wheel bearing noise, but is in the same frequency as the rear wheel bearings.

### Common Causes of Bearing Related Noises

The following list are common causes of bearing related noises:

1. Low lubricant level.
2. Incorrect lubricant used.
3. Foreign matter in the lubricant.
4. Incorrect preload setting.
5. Incorrectly mounted bearings (eg. dirt trapped behind abutment faces during the assembly).