Bearing Whine

- Bearing whine is a high-pitched sound similar to a whistle. It is usually caused by malfunctioning pinion bearings, which are operating at driveshaft speed. Bearing noise occurs at all driving speeds. This distinguishes it from gear whine which usually comes and goes as speed changes. However if there is only one differential pinion bearing that is malfunctioning, the noise may vary in different driving phases.
- Differential pinion bearings are frequently replaced unnecessarily on axles with mileage under 24,139 km (15,000 miles) when correcting gear noise. They should not be replaced unless they are actually scored or damaged, or there is a specific pinion bearing noise. Examine the large end of the rollers for wear. If the bearing's original blend radius has worn to a sharp edge. the differential pinion bearing should be replaced.