Rear Hub Bearing

Axle Bearing Inspection

General
Bearing malfunctions normally will be obvious at disassembly. Pinion bearings make a high-pitched, whistling noise, usually at all speeds. However, if there is only one pinion bearing that is malfunctioning. the noise may vary in different driving phases.

Pinion Bearings
Pinion bearings are frequently replaced unnecessarily 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 original blend radius has worn to a sharp edge, the bearing assembly should be replaced.

NOTE: The low-pitched rumble of a malfunctioning wheel bearing can be duplicated by a wind noise from externally mounted accessories or by tires.

Semi-Floating Axles
On semi-floating type axles, wheel bearing noise might be mistaken for pinion bearing noise, so be sure to look at the wheel bearings carefully before disassembling the axle.

Wheel bearings on semi-floating type axles are pressed into the housing at the axle tube ends. The axle shaft is the inner race for the bearing. The rollers can run on about the center of the polished surface. So if the bearing is damaged, the roller surface on the shaft will be damaged as well.