Differential Assembly: Description and Operation

Getrag Rear Axle
The service procedure covers the Getrag 2.73, 3.42, and 3.15 ratio rear axles. All rear axle differential carriers and differential carrier side covers are constructed of cast aluminum.

The 2.73 ratio axle is used in vehicles with automatic transmissions while the 3.42 ratio axle is used in vehicles with manual transmissions. The 3.15 ratio axle is an optional ratio axle for automatic transmission applications. All models have a 7 5/8 inch ring gear.

The rear axle is mounted to the rear of the transmission. The rear transaxle assembly is mounted to the rear crossmember. Torque is transmitted through the transmission output shaft which is splined directly to the rear axle pinion.

The internal components of the differential carrier incorporates a hypoid gear set with a pinion supported in a bearing cartridge consisting of two preloaded, taper roller bearing assemblies, and a differential case assembly supported on taper roller bearings. The pinion is positioned aft of the ring gear centerline.

Pinion mounting distance adjustments are made through the use of shims, as are the differential bearing preload and mounting distance adjustments. Unlike conventional shimming procedures, all ring and pinion gear sets are stamped with setup dimensions that are particular to that gear set. These numbers are derived from actual noise and accelerometer measurements of each gear set. When calculated with additional differential carrier measurements, it will determine shim size selection to ensure quiet axle operation.

The limited-slip differential is a conventional plate type design. The differential side gears through the use of splined shafts, drive two splined yokes that are part of the rear axle shafts. Lip type oil seals pressed into the differential carrier side covers prevent lubricant leakage and dirt entry.

The vehicle speed sensor is located on top of the differential carrier housing. Rotational pulses are produced by a reluctor wheel that is part of the ring gear. The lubricant fill plug is located on the rear of the differential carrier housing.