Bearing Noise (Drive Pinion Gear Shaft and Differential)

Defective or damaged bearings will normally produce a rough growl. This growl is constant in pitch and varies with the speed of the vehicle. Being aware of this will enable a technician to separate bearing noise from gear noise.

Drive pinion bearing noise that results from defective or damaged bearings can usually be identified by its constant, rough sound. The drive pinion front bearing is usually more pronounced during a coast condition. The drive pinion rear bearing noise is more pronounced during a drive condition. The drive pinion bearings are rotating at a higher rate of speed than the differential side bearings.

Side bearing noise will usually produce a constant, rough sound that is much lower in frequency than drive pinion bearing noise.

Bearing noise can best be detected by road testing the vehicle on a smooth road (black top). However, it is easy to mistake tire noise for bearing noise. If a doubt exists, the tire treads should be examined for irregularities that often causes a noise that resembles bearing noise.