A/T - No Reverse or Slipping in Reverse
Number: 93-19-7ASection: 7A
Date: OCT. 1992
Corporate Bulletin No.: 277143
ASE No.: A2
Subject:
NO REVERSE OR SLIPPING IN REVERSE
Model and Year:
1992-93 CORSICA, BERETTA, CAVALIER AND LUMINA
1992-93 LUMINA APV
TRANSMISSION APPLICATIONS:
1992-93 HYDRA-MATIC 3T40 (MD9) (THM 125-C)
TRANSMISSION MODELS:
All
SUBJECT:
No Reverse or Slipping in Reverse (Install New Lo/Rev Clutch Return Spring and Spiral Retaining Ring)
VEHICLE APPLICATIONS:
J, L, and W - Cars U - Van
CONDITION:
Some 1992-1993 HYDRA-MATIC 3T40 transaxles in J, L, W cars and U vans may slip in reverse, or have no reverse gear.
CAUSE:
Internal fluid leaks in the lo and reverse clutch circuit can cause the lo and reverse clutch piston to partially apply when the transaxle is in a drive gear. The current return spring load may not be great enough to keep the piston from partially applying.
CORRECTION:
Replace the lo and reverse clutch return spring, spring retainer and snap ring with a new design clutch belleville return spring and spiral retaining ring. The new clutch return spring has a higher spring rate to keep the piston from partially applying.
SERVICE INFORMATION:
1993 HYDRA-MATIC 3T40 transaxles built beginning July 1, 1992 (Julian Date 182) already contain the new design return spring and spiral retaining ring. The new return spring and spiral retaining ring can be used to service any 1992-1993 HYDRA-MATIC 3T40 (previously THM 125-C) transaxle.
NOTICE:
Do not install the new design return spring in 1991 or previous HYDRA-MATIC 3T40 transaxles. These models have not had their hydraulic pressures re-calibrated to accept the new spring with a higher spring rate. Transaxle damage will result if this new return spring is installed in 1991 or previous HYDRA-MATIC 3T40 models.
If the previous design return spring and retainer is being replaced with the new design, install the lo blow off line-up from the service package into the transaxle when the return spring is changed.
No change was made to the piston or housing.
The lo and reverse clutch spring retainer (656) was eliminated in the design change.
SERVICE PARTS INFORMATION:
Parts are currently available from GMSPO.
PARET NUMBER Part Name
8687998
PART NAME
Repair Kit - Lo/rev Belleville Spring and Retainer (includes new belleville return spring (655), new spiral retaining ring (657), lo blow off spring and plug (325) and lo blow off valve plug (326))
Part numbers are for Reference Only.
Check with your Parts Department for latest information.
SERVICE MANUAL REFERENCE:
Refer to the HYDRA-MATIC 3T40 Automatic Transaxle Unit Repair Section of the appropriate Service Manual for instructions on servicing the lo/reverse clutch. Figure 3 of this bulletin shows the installation orientation of the new belleville return spring and spiral retaining ring.