Bearing Noise

Defective or damaged bearings will normally produce a rough growl. This growl is constant in pitch and varies with speed of vehicle. Being aware of this will enable a technician to properly diagnose bearing noise. Transaxle bell housing input shaft bearing noise that results from defective or damaged bearings can usually be identified by its constant, rough sound. The shaft front bearing noise is usually more pronounced during a coast condition. The shaft rear bearing noise is more pronounced during a drive condition.

Bearing noise can best be detected by road testing vehicle on a smooth road (black top). However, it is easy to mistake tire noise for bearing noise. If a doubt exists, tire treads should be examined for irregularities that often causes a noise that resembles bearing noise. The most important part of service is correctly identifying cause of failures and noise complaints. The cause of most failures is relatively easy to identify. However cause of noise is much more difficult to identify. If vehicle noise becomes objectionable, isolate noise to one area of vehicle.

Many noises that are reported as coming from one source may actually originate at other sources. For example: tires, road surfaces, wheel bearings, engine, transmission, exhaust, or vehicle body. A thorough and careful inspection should be completed to determine actual source of noise. This should be done before any disassembly and component inspection is initiated. The mounting bushings help to dampen-out noise when correctly installed. Inspect to confirm that no metal contact exists between bell housing and frame. Metal-to-metal contact can result in a noise. This noise could be eliminated if components were correctly installed and tightened. The complete isolation of noise to any one area requires considerable expertise and experience.

All bearings produce noise to a certain extent. Slight bearing noise at certain speeds or isolated situations are considered normal.