S10/T10 P/U 2WD V6-262 4.3L (1988)
Technical Service Bulletin # 914047A
Date: 910801
Transfer Case - Increased Shift Effort From 2H to 4H
Number: 91-404-7A
Section: 7A
Date: AUGUST 1991
Corporate Bulletin No.: 167401
ASE No.: A2
Subject:
HIGH TRANSFER CASK SHIFT EFFORT
Model and Year:
1988-91 T1 TRUCKS
Some 1988-91 T-Trucks may experience high transfer case shift effort or total blockouts when "shifting on the fly" from 2H to 4H under cold weather
conditions.
This condition may be corrected by the installation of the synthetic 75W90 gear lube described in Dealer Service Bulletin No. 91-128-7A. This fluid
maintains a more constant viscosity under cold weather conditions allowing quicker front axle synchronization and easier transfer case engagement.
If the installation of the synthetic fluid does not result in a satisfactory shift effort, an "Easy Shift" package may be installed in the transfer case. This
package features a roller pin (53) rather than a solid pin on the mode shift fork (54) and revised ramp angles on the sector (55) to reduce engagement
forces. This package was installed in the 1991 model year and will provide reduced transfer case shift effort under cold weather conditions.
Figure 1
VEHICLES INVOLVED:
Group A:
Some 1988-91 T-Trucks equipped with transfer cases identified by the following part numbers:
15568078
15627441
15568079
15627442
15568597
15653450
