GM Service Manual Online
For 1990-2009 cars only

Cause

Correction

DEFINITION: During acceleration or deceleration, a clunk is heard or felt in the transfer case while in the 2HI mode.

Review the Symptoms - Transfer Case and perform the necessary inspections.

Incorrect fluid level or incorrect fluid

  1. Inspect the transfer case for the correct fluid level.
  2. Inspect the transfer case for the correct type of fluid. Refer to Approximate Fluid Capacities .
  3. Flush the transfer case and fill with the correct fluid, if required. Refer to Transfer Case Fluid Replacement .

Excessive clearance between the slip yoke and the rear output shaft

  1. Inspect for the following conditions:
  2. • Worn slip yoke splines
    • Worn rear output shaft splines
  3. Repair or replace the following components if faulty:
  4. • Replace the slip yoke, if required. Refer to Rear Propeller Shaft Replacement .
    • Replace the rear output shaft, if required. Refer to Transfer Case Disassemble and Transfer Case Assemble .

Excessive clearance between the slip yoke and the rear bushing

  1. Inspect for the following conditions:
  2. • Worn rear bushing
    • Worn slip yoke bushing journal
  3. Repair or replace the following components if faulty:
  4. • Replace the slip yoke, if required. Refer to Rear Propeller Shaft Replacement .
    • Replace the rear bushing if worn.
       - For light duty vehicles, refer to Transfer Case Rear Extension Bushing Replacement .
       - For heavy duty vehicles, refer to Transfer Case Disassemble and Transfer Case Assemble .

Input shaft thrust washers

  1. Inspect for worn or missing input shaft thrust washers.
  2. Replace the thrust washers as required. Refer to Transfer Case Disassemble and Transfer Case Assemble .

Worn high speed teeth on the high/low clutch

  1. Inspect for worn high speed teeth on the high/low clutch. Refer to High/Low Shift Components Cleaning and Inspection .
  2. Replace the high/low clutch if worn. Refer to Transfer Case Disassemble and Transfer Case Assemble .

Rear output shaft rear bearing outer retaining ring

  1. Inspect for the following conditions:
  2. • Properly installed rear output shaft rear bearing outer retaining ring
    • Excessive wear or damaged retaining ring groove in the rear case half
  3. Repair or replace the following components if found faulty.
  4. • Properly install a new rear output shaft rear bearing outer retaining ring.
    • Replace the rear case half if the retaining ring groove is excessively worn.