Transfer Case - Noise in 2 Wheel Drive
87chevy24Number: 86-249
Section: 7D
Date: September, 1987
SUBJECT: 207 TRANSFER CASE NOISE IN WHEEL DRIVE
MODELS: 1985-86 T TRUCKS
FIGURE NO. 1:
Some 1985 and 1986 T trucks may experience a high pitched (bearing type) whining noise while operating in 2 wheel drive. These vehicles can be checked for this condition by applying firm pressure to the transfer case shift lever and pulling the lever in the direction of 4 High. If this eliminates the whining noise, the condition can be repaired by replacing the two sprocket bearings (See Figure No. 1 - Item 31). This condition is caused by the needle bearings which are inside the sprocket bearing having skewed (turn slightly sideways), which causes them to slide instead of roll. The above situation was repaired by using a caged bearing on transfer cases dated 4-1-86 and later, which can be identified by the serial number tag that is located on the rearward side
of the transfer case. The serial number is the Date Code. Example - Serial Number 4-1-86 (April 1, 1986).
SERVICE PARTS
P/N 9442178 - Sprocket Bearing/2 Required per vehicle (caged)
NOTE: New style sprocket bearings can be identified by vendors name which is stamped on the side, "INA".
SERVICE MANUAL
Refer to the 1986 Unit Repair Manual, Section 7D, for procedures to replace the sprocket bearing.