Transmission Output Shaft Bearing

Replace the transmission output shaft bearing by removing the driveshaft, rear transmission housing, and disassembling internal components to access and replace the worn bearing.

Warnings

Tools required

Parts

• Transmission output shaft bearing × 1 — Use OEM specification for ZF 8HP70
• Transmission pan gasket × 1 — Use OEM specification
• Rear transmission housing gasket × 1 — Use OEM specification
• Output shaft seal × 1 — Use OEM specification
• Transmission drain plug crush washer × 1 — Use OEM specification
• Snap ring (if damaged during removal) × 1 — Use OEM specification

Fluids

• ZF Lifeguard 8 — 10 qt

Preparation

1. Park vehicle on level lift and engage parking brake
2. Disconnect negative battery terminal and wait 10 minutes for system capacitor discharge
3. Raise vehicle to comfortable working height and support with jack stands at manufacturer lift points
4. Remove rear wheels to access driveshaft connections
5. Remove exhaust system center section to access transmission and driveshaft
6. Remove driveshaft heat shields
7. Place transmission drain pan under transmission
8. Allow transmission to cool to ambient temperature if recently driven

Procedure

1. 1

   Drain transmission fluid
   Remove the transmission drain plug from the oil pan using appropriate socket. Allow all fluid to drain completely into drain pan (approximately 10 quarts). Inspect drained fluid for metal particles or debris which may indicate additional internal damage. Remove and replace crush washer on drain plug.
   Torque spec

   Drain Plug35 Nm (26 lb-ft)
2. 2

   Remove transmission pan
   Remove transmission pan bolts in reverse criss-cross pattern to prevent warping. Carefully lower pan and inspect for metal debris or clutch material. Clean pan thoroughly and inspect magnet for excessive metal particles. Remove and discard pan gasket.
   Torque spec

   Pan Bolts18 Nm (13 lb-ft)
3. 3

   Disconnect driveshaft
   Mark driveshaft-to-differential flange alignment with paint marker. Remove four driveshaft flange bolts at rear differential. Support driveshaft center bearing and remove mounting bolts. Carefully slide driveshaft rearward out of transmission output housing. Cap transmission output to prevent fluid leakage and contamination.
4. 4

   Remove transmission sensors and electrical connections
   Disconnect all electrical connectors from transmission: output speed sensor, input speed sensor, transmission range sensor, and solenoid pack connector. Remove sensor bolts and carefully extract sensors. Place sensors in clean, organized location to prevent damage or contamination.
   Torque spec

   Sensor Bolts11 Nm (8 lb-ft)
5. 5

   Support and lower transmission
   Position transmission jack under transmission oil pan with wooden block to distribute load. Secure transmission to jack with safety straps. Remove transmission mounting bolts connecting transmission to crossmember and engine. Carefully lower transmission approximately 6 inches to gain access to rear housing bolts. Ensure all electrical connectors and cooler lines have sufficient slack.
   ⚠️Transmission must be properly secured to jack before removing mounting bolts. Shifting load can cause severe injury.
   Torque spec

   Mounting Bolts64 Nm (47 lb-ft)
6. 6

   Remove rear transmission housing
   With transmission lowered and supported, locate and remove all rear housing cover bolts (typically 12-15 bolts around perimeter). Tap housing gently with plastic mallet to break gasket seal. Carefully pull housing straight back to separate from main case. The output shaft and parking pawl assembly will be visible. Support housing and set aside on clean surface.
   ⚠Do not pry between housing and case as this will damage sealing surfaces.
   Torque spec

   Cover Screws11 Nm (8 lb-ft)
7. 7

   Remove output shaft assembly
   Locate snap ring securing output shaft in housing. Use appropriate snap ring pliers to remove snap ring. Note snap ring orientation for reassembly. Carefully pull output shaft assembly from housing. If stuck, use slide hammer with internal puller attachment. The output shaft bearing will either come out with shaft or remain in housing bore.
8. 8

   Remove old bearing
   If bearing remained in housing, use bearing puller to extract bearing from bore. If bearing is on shaft, use hydraulic press or bearing separator to press bearing off shaft. Inspect output shaft journal surfaces for scoring, wear, or damage with micrometer. Shaft journal must be within 0.02mm tolerance of specification. Clean shaft thoroughly with lint-free cloth and brake cleaner.
   ⚠Never strike bearing directly with hammer as this will damage housing bore or shaft journal.
9. 9

   Install new bearing
   Place new output shaft bearing in freezer for 30 minutes to contract inner race. Heat housing bore area gently with heat gun to expand (do not exceed 100°C). Using appropriate bearing driver that contacts only outer race, press or drive bearing squarely into housing bore until fully seated against shoulder. Verify bearing is fully seated by measuring depth at multiple points around circumference. Install new snap ring ensuring it is fully seated in groove.
   ⚠Bearing must be pressed squarely to prevent cocking which will damage bearing and housing.
10. 10

    Measure bearing preload
    Install output shaft into new bearing. Using dial indicator mounted to housing, measure shaft end play. End play should be 0.05-0.15mm. If end play is excessive, verify snap ring is correct thickness and properly seated. Rotate shaft by hand to verify smooth rotation without binding. Install new output shaft seal using seal driver.
11. 11

    Reinstall rear housing
    Clean all gasket surfaces on rear housing and transmission case with gasket remover and lint-free cloth. Apply new gasket or thin bead of RTV silicone to housing mating surface. Carefully align rear housing with transmission case, ensuring output shaft engages properly with internal components. Install all housing bolts finger tight, then torque in criss-cross pattern in three stages: 50%, 75%, then 100% of specification.
    Torque spec

    Cover Screws11 Nm (8 lb-ft)
12. 12

    Raise and secure transmission
    Using transmission jack, carefully raise transmission back to original position aligning with engine and crossmember mounting points. Install transmission mounting bolts and apply thread locker to threads. Torque mounting bolts to specification in criss-cross pattern.
    Torque spec

    Mounting Bolts64 Nm (47 lb-ft)
13. 13

    Reinstall sensors and driveshaft
    Install all transmission sensors with new O-rings if equipped. Torque sensor bolts to specification. Reconnect all electrical connectors ensuring positive engagement. Remove output shaft cap and slide driveshaft into transmission output splines. Align driveshaft flange to differential flange using paint marks made during removal. Install and torque flange bolts. Reinstall center bearing support.
    Torque spec

    Sensor Bolts11 Nm (8 lb-ft)
14. 14

    Reinstall transmission pan and fill
    Install new transmission pan gasket. Position pan and install bolts finger tight. Torque pan bolts in criss-cross pattern starting from center working outward to specification. Install drain plug with new crush washer and torque to specification. Using fluid pump, fill transmission with ZF Lifeguard 8 fluid through fill tube. Fill to approximately 9 quarts initially.
    Torque spec

    Pan Bolts18 Nm (13 lb-ft)

    Drain Plug35 Nm (26 lb-ft)
15. 15

    Final fluid level adjustment
    Reconnect battery negative terminal. Start engine and allow to idle. Shift through all gear ranges pausing 3 seconds in each position. Return to Park. With engine running and transmission at operating temperature (80-90°C), check fluid level at fill plug location. Add fluid as necessary to achieve proper level (fluid should just drip from fill hole). Install fill plug with new washer and torque to specification.
    Torque spec

    Fill Plug35 Nm (26 lb-ft)

Reassembly

1. Reinstall exhaust center section and heat shields
2. Reinstall rear wheels and torque lug nuts to specification
3. Verify all electrical connectors are properly seated
4. Double-check all fasteners are torqued to specification
5. Verify no tools or parts are left in vehicle or under vehicle

Verification

• Start engine and verify no transmission fluid leaks from pan, housing, or sensors
• Test drive vehicle through all gear ranges verifying smooth shifts
• Check for abnormal noises from transmission during acceleration and deceleration
• Verify transmission output shaft bearing noise is eliminated
• Recheck transmission fluid level after 50-mile break-in period
• Clear any diagnostic trouble codes and verify no new codes are present
• Monitor transmission temperature during test drive to ensure proper operation

Related trouble codes on this vehicle

Codes that commonly send this job to the bay — tap one for symptoms, causes, and diagnostic steps.

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