Noise Diagnosis - Rear Drive Axle

Ring and Pinion Gear Noise
Noise produced by the ring and pinion gearset is of a cyclic nature. The following is a list of the noises:
^ A drive noise. A drive noise is most pronounced on constant acceleration through the speed range of 50 km/h to 90 km/h (33 mph to 60 mph).
^ A coast noise. A coast noise is most pronounced when the vehicle is allowed to coast through the speed range from 90 km/h to 50 km/h (60 mph to 33 mph).
^ A flat noise. A flat noise is most pronounced while the vehicle is kept at a constant speed for periods between 50 km/h and 90 km/h (33 mph and 60 mph).
Differential noise always changes when comparing drive and coast. Differential noise usually ceases when coasting with the transmission in neutral at speeds under 50 km/h (33 mph).

Differential Side and Pinion Gear Noise
The noise produced by the differential side gear and pinion gear occurs when there is an excessive wear between the side gear hubs and the differential case bores. This can cause a clunking noise when the vehicle is driven at low speeds. Noise produced due to excessive wear between the gear teeth is most pronounced on turns.

Common Causes of Gear Related Noises
The following list are the common causes of gear related noises:
^ A low lubricant level.
^ An incorrect lubricant used.
^ An incorrect meshing of the gear teeth (i.e. incorrect pinion positioning shim or incorrect backlash setting adjustment).
^ Scored gear teeth. Scored gear teeth are usually the result of incorrect lubricant type or incorrect lubricant level.
^ Endplay in the bearings.
^ Bruised teeth.
^ Chipped teeth.
^ An excessive runout of the differential drive pinion gear head.
^ Ring gear backlash.
^ Ring gear creeping on the differential carrier. Ring gear creeping on the differential carrier results from loose ring gear bolts. This noise usually appears as a sharp metallic sound when shifting from reverse to first gear.