A/T - Production Changes Hm-290/Hydra-Matic 5LM60
89chevy13GMC NUMBER: 89-T46
GROUP: 7B - Manual Transmission
DATE: April, 1989
CORPORATE
NUMBER: 977201R
SUBJECT: 1989 MODEL YEAR PRODUCT CHANGES - HM-290/HYDRA-MATIC 5LM60
MODELS: TRUCK SERIES C1, C2, K1, K2
Figure 1 - Transmission - Gear Components:
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 accom-
modate 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.
Service Notes:
Except for eliminated parts, assembly and disassembly procedures for the HM-290/HYDRA-MATIC 5LM60 are unchanged.
Figure 3 - HM-290/Hydra-matic 5LM60 Transmission Identification Information RPO MC0/MG5:
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 servidng 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
Parts are currently available from GMSPO.