General Information-Noise Diagnosis

The most important part of rear axle service is correctly identifying the cause of failures and noise complaints. The cause of most rear axle failures is relatively easy to identify. However the cause of rear axle noise is much more difficult to identify.

If vehicle noise becomes objectionable, isolate the noise to one area of the vehicle. Many noises that are reported as coming from the differential may actually originate at other sources. For example: tires, road surfaces, wheel bearings, engine, transmission, exhaust, or vehicle body. Differential noises are normally divided into two categories: gear noise or bearing noise. A thorough and careful inspection should be completed to determine the actual source of the noise. This should be done before axle disassembly and component inspection is initiated.

The mounting bushings help to dampen-out differential noise when correctly installed. Inspect to confirm that no metal contact exists between the differential case and the body. Metal-to-metal contact can result in a noise. This noise could be eliminated if the components were correctly installed and tightened. The complete isolation of noise to any one area requires considerable expertise and experience.

All differentials produce noise to a certain extent. Slight differential noise at certain speeds or isolated situations are considered normal. Differential noise tends to peak at a variety of vehicle speeds. Differential noise is not always an indication of a problem.