GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Buick 🢒 2008 🢒 Lucerne 🢒 Transmission/Transaxle 🢒 Automatic Transaxle - 4T80-E 🢒 Final Drive Assembly Replacement

Removal Procedure
  1. Remove the case extension. Refer to Case Extension Replacement .

    2. Object Number: 11841 Size: SH
  2. Rotate the manual shaft (16) counterclockwise in order to place the transaxle in Park (P) and prevent the differential from rotating.

    3. Object Number: 687629 Size: SH
  3. Remove the 4 bolts (119) from the differential housing to transaxle case.
  4. Remove the differential carrier.

    5. Object Number: 11843 Size: SH
  5. Push on the output shaft in order to expose the left side differential gear snap ring. Remove the left side differential gear to output shaft snap ring (56).
  6. Remove the differential side gear (118) and thrust washer (117).

    7. Object Number: 687589 Size: SH
  7. Remove the final drive carrier (100) and the thrust bearing.
  8. Remove the final drive sun gear (121).

Installation Procedure

    Object Number: 687589 Size: SH
  1. Install the sun gear (121) with the bushing and the seal side facing differential.
  2. Install the final drive carrier (100). Turn the unit until it meshes with the sun gear and the internal gear teeth.

    3. Object Number: 11843 Size: SH
  3. Install the left thrush washer (117).
  4. Install the left differential side gear (118).
  5. Install the snap ring (56).

    6. Object Number: 687629 Size: SH
  6. Use the manual shaft to place the transaxle in park.

    7. This will lock up the final drive unit. The actuator rod will move up.

    Notice: Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems.

  7. Install the differential housing and the four bolts (119). Hand tighten, using a star pattern.

    8. Tighten
    Tighten the bolts to 76 N·m (56 lb ft).

  8. Install the case extension. Refer to Case Extension Replacement .