C 1500 Truck 2WD V8-350 5.7L (1989)
Fluid - Transfer Case: Customer Interest
Transfer Case - High Shift Effort When Shifting
Number: 91-165-7A
Section: 7A
Date: January 1991
Corporate Bulletin No.: 967402R
Subject:
HIGH TRANSFER CASE SHIFT EFFORT
Model and Year:
1983-91 T1 TRUCKS 1988-91 K TRUCKS
TO: ALL CHEVROLET DEALERS
THIS BULLETIN CANCELS AND SUPERSEDES DEALER SERVICE BULLETIN NO. 91-128-7A, DATED NOVEMBER 1990. THE BULLETIN
NUMBER HAS BEEN CORRECTED IN THE FIRST PARAGRAPH. ALL COPIES OF 91-128-7A SHOULD BE DISCARDED.
Some four wheel drive K and T trucks may experience high transfer case shift effort and/ or total blockouts when "SHIFTING ON THE FLY" from 2H
to 4H under cold weather conditions (usually 25 degrees or less). In order to shift to 4H the speed of the front propshaft must be increased to allow
proper engagement of front axles. As the transfer case shift lever is moved into 4H the front propshaft begins rotating to synchronize the front axle
assembly. In cold weather conditions regular production lube has high viscosity which may delay or prohibit the synchronizing of the front propshaft and
axle resulting in high transfer case shift effort.
To reduce high shift effort, regular production front axle gear lube may be replaced with a 75W-90 synthetic gear lube which maintains a lower viscosity
under cold weather conditions. This synthetic gear lube is now available in one quart containers from GMSPO. Before installing, it is important to drain
and flush the front axle with clean mineral based (non synthetic) axle lube. The front axle should then be refilled to the level of the filler hole with
synthetic lube listed below.
Front Axle Lube Capacities:
K1, K2 - 1.66 liter (1.75 qts)
K3
- 2.13 Liter (2.2 qts)
T1
- 1.20 liter (1.3 qts)
SERVICE PARTS INFORMATION
P/N
DESCRIPTION
12345836
SAE 75W-90 synthetic gear lube, 1 qt. bottle
Parts are currently available from GMSPO.
WARRANTY INFORMATION For vehicles repaired under warranty use:
Labor Operation Number:
T7980
Labor Time:
.4 hr
Trouble Code:
92
NOTE:
Labor Operation is coded to base vehicle coverage in the warranty system.
