A/T - Wrong Case Extension, ATF Leak/Vibration

Group Ref.: Transmission
Bulletin No.: 377122
Date: January, 1994

SUBJECT:
VIBRATION/FLUID LEAK OUT OF CASE EXTENSION (REPLACE CASE EXTENSION ASSEMBLY)

MODELS:
1993 CHEVROLET AND GMC C AND P TRUCKS AND G-VAN

TRANSMISSION MODELS:
ABP, ADP, AFP, DCP, DSP, TXP, TWP, LAP, MHP, JDP, BAP, BSP, MAP, MBP, MCP, MJP, MLP

TRANSMISSION APPLICATIONS:
1993 HYDRA-MATIC 4L80-E/4L80-EHD (MT1)

THIS BULLETIN HAS BEEN REVISED TO CORRECT THE PARTS INFORMATION. PREVIOUS DIVISIONAL PUBLICATION NUMBERS WERE:

DIVISION BULLETIN #

CHEVROLET 93-185-7A

GMC TRUCK 93-7A-75

GM CANADA 93-7A-140

HYDRA-MATIC 9374L80E09

CONDITION:
Some HYDRA-MATIC 4L80-E/4L80-EHD transmissions may leak fluid at the back of the case extension assembly (19) or a vibration may be noticed in all ranges at all speeds.

CAUSE:
This is caused by the extension bushing (77) not seated properly due to an oversized bore, possibly interfering with the case extension helix-seal assembly (20).





CORRECTION: (Figure 2)

Inspect the case extension helix-seal assembly (20) for any damage and see if the bushing (77) has moved. If the bushing has moved, order a new case extension assembly (19) which includes the properly installed bushing and install a new helix-seal assembly (20).

Do not attempt to repair the extension by staking, sealing, or securing bushing in place.





SERVICE INFORMATION: (Figure 1)

Starting January 14, 1993 (Julian Date 014) all 1993 HYDRA-MATIC 4L80-E/4L80-EHD models will have the corrected case extension assembly.





PARTS INFORMATION:

Parts are currently available at GMSPO.