Buick Regal: Description and Operation

POWER TRANSFER UNIT CASE IDENTIFICATION

The power transfer unit primary identification label (1) is located on the rear extension housing. The power transfer unit secondary identification stamping (2) is located on the bottom of the main housing.

Transfer Case Primary Identification Label

1. GM Part Number
2. Broadcast Code
3. Supplier Manufacturing Location
4. VPPS
5. Broadcast Code / Trace Code

Transfer Case Secondary Identification Stamping

1. GM Part Number
2. Build Hour
3. Daily Build Count
4. Day of the Year
5. Model Year
6. BOM Code

POWER TRANSFER UNIT CASE DESCRIPTION AND OPERATION

General Description

The power transfer unit is positioned in the right side of the vehicle and mounts to the transmission and the engine.

The primary function of the power transfer unit is to receive power from the transmission and transfer it using helical and hypoid gear sets through the propeller shaft to the rear differential. The power transfer unit main housing, extension housing, and rear output shaft housing are of a cast aluminum design.

External Components

1. Power Transfer Unit weep hole location - Main Case
2. Power Transfer Unit Vent Hose Assembly
3. Power Transfer Unit Input Shaft - Transmission Input
4. Power Transfer Unit weep hole location - Extension Housing
5. Power Transfer Unit Intermediate Drive Shaft - Right Axle Shaft
6. Intermediate Drive Shaft Oil Seal
7. Power Transfer Unit Oil Fill Plug
8. Power Transfer Unit Oil Drain Plug
9. Power Transfer Unit Rear Output Shaft

Internal Components

The OD splines of the input shaft (4) are mated to the ID splines of the transmission output shaft. Power and torque are transferred from the input shaft (2) to the idler shaft (6) via a helical gear set. A second gear set, the hypoid gear set transfers power and torque from the idler shaft to the rear output shaft (1). The propeller shaft is mated to the rear output shaft providing power and torque to the rear drive axle. The OD splines of the intermediate drive shaft (3) mate to the ID splines of the transmission carrier assembly and provide power and torque to the right front axle shaft and wheel.

Gear tooth clearances and bearing preloads are maintained by shims located behind the bearing races. The housings, internal gears, and bearings are not serviceable components. If housing, gear set, or bearing damage occurs, the assembly must be replaced.

1. Power Transfer Unit Rear Output Shaft
2. Power Transfer Unit Input Shaft
3. Power Transfer Unit Intermediate Drive Shaft-to-Transmission Splines
4. OD Splines of the Input Shaft
5. Power Transfer Unit Input Shaft Seal - Front
6. Power Transfer Unit Idler Shaft
7. Power Transfer Unit Input Shaft Seal - Rear
8. Power Transfer Unit Cover-to-Intermediate Drive Shaft Seal-at-Extension Housing
9. Power Transfer Unit Intermediate Drive Shaft

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