Transfer Case Clunk in 4LO

WARNING: This page is about a different car, the 2009 GMC Yukon, 2009 Chevrolet Tahoe, 2009 Chevrolet Suburban, and 2009 Chevrolet Avalanche. However, it is still accessible from the selected car via links, so may be relevant.

Cause	Correction
DEFINITION: During acceleration or deceleration, a clunk is heard or felt in the transfer case while in the 4LO range only. Review the Symptoms - Transfer Case and perform the necessary inspections.
High/low planetary carrier assembly	Inspect for the following conditions: Excessively worn planetary gears The planetary gears loose in the planetary carrier The input shaft for missing thrust washers or excessive thrust end play in the carrier Excessively worn high/low clutch engagement teeth on the carrier Refer to High/Low Planetary Carrier Cleaning and Inspection . Replace the high/low planetary if any of the above conditions are found. Refer to Transfer Case Disassemble and Transfer Case Assemble .
High/low internal gear	Inspect the high/low internal gear to front case fit for any looseness. Replace the front case half if the high/low internal gear is loose. Refer to Transfer Case Disassemble and Transfer Case Assemble .
High/low clutch	Inspect the high/low clutch engagement teeth for excessive wear. Inspect the high/low clutch to rear output shaft splines for excessive wear. Replace the high/low clutch if faulty. Refer to Transfer Case Disassemble and Transfer Case Assemble .