A/T - Production Change Details
89Chevy16Number: 89-107-7B
Section: 7B
Date: MARCH, 1989
Subject: HM-290 HYDRA-MATIC 5LM60 1989 MODEL YEAR PRODUCT CHANGES
Model and Year: 1989 C1, C2, K1, K2 TRUCKS
Figure 1 - Transmission - Gear Components:
TO: ALL CHEVROLET DEALERS
This bulletin covers changes made for better manufacturing processes and product serviceability.
Change - New output shaft bearing assembly (33). The new bearing is thinner and serviced only as a sealed unit (Figure 1).
Reason - Serviceability and better resistance to contamination.
Change - New output shaft (23/24) (Figure 1). Reason - Dimensional changes needed to accomodate new bearing, threaded thrust ring elimination.
Change - Threaded thrust ring assembly (39-42) eliminated (Figure 1).
Reason - New design has better serviceability, saves material.
Change - New reverse idler shaft assembly (46) eliminates 2 needle bearing assemblies (50), 4 mm ball (40) and O-ring (52) (Figure 1).
Reason - New design has better serviceability, saves material.
Figure 2 - Transmission -Shift Mechanism And Case Components:
Change - New rear housing (300) (Figure 2). Reason - Dimensional changes needed for new output and reverse idler shafts, reverse idler shaft bore eliminated, revised bore location for new speed sensor (2WD only).
Change - New speed sensor (2WD only) (314) (Figure 2). Reason - Revised location requirements.
Change - New shift shaft select bias system (229-237) eliminates 5th and reverse detent assembly (204, 239-241, 247-248) and bore in front housing (200) (Figure 2).
Reason - Improved shift feel.
Figure 3 - HM-290/Hydra-matic 5LM60 Transmission Identification Information RPO MCO/MG5:
SERVICE NOTES:
Except for eliminated parts, assembly and disassembly procedures for the HM-290/HYDRA-MATIC 5LM60 are unchanged.
DATE OF PRODUCTION CHANGE: (Figure 3)
The changes listed above were implemented January 7, 1989 (Build Date A 07) for C-Truck applications (2WD) and January 11, 1989 (Build Date A 11) for K-Truck applications (4WD).
SERVICE PARTS INFORMATION:
Refer to the following list for part information when servicing a HM-290/HYDRA-MATIC 5LM60 built after the dates listed above. Refer to current GMSPO catalog when servicing previous units.
Do not mix previous and new parts-the unit will not assemble properly.
APPLICATION
PART NO. PART NAME C K
8672318 Shaft-Output (23) X
8672315 Shaft-Output (24) X
8672210 Bearing Asm-Output Shaft (33) X X
8672200 Shaft-Reverse Idler (51) X X
8672201 Bearing Asm-Needle Reverse Idler (50) X X
8672202 Gear-Reverse (49) X X
8672203 Washer-Thrust (48) X X
8672282 Housing Asm-Rear (300) X
8672285 Housing Asm-Rear (301) X
8672317 Housing Asm-Front (200) X X
8672237 Speed Sensor-Internal Trans (314) X
8672244 Lever Asm-Shift Shaft (229) X X
8672248 Spring-Bias Load Torsion (234) X X
8672247 Support-Bias Spring (237) X X
8672207 Rotor-Speed Sensor (45) X