A/T - Harsh Clutch Engagement Reverse To Drive

Group Ref.: Transaxle

Bulletin No.: 377134

Date: November, 1993

SUBJECT:
HARSH CLUTCH ENGAGEMENT "GARAGE SHIFT"
(INSTALL CONVERSION KIT)

MODELS:
1993 BUICK CENTURY, SKYLARK, AND REGAL
1993 CHEVROLET CAVALIER, LUMINA, AND LUMINA APV
1993 OLDSMOBILE ACHIEVA, CUTLASS CIERA, CUTLASS SUPREME, AND SILHOUETTE
1993 PONTIAC GRAND AM, GRAND PRIX, LEMANS, SUNBIRD, AND TRANS SPORT

TRANSAXLE APPLICATIONS:
1993 HYDRA-MATIC 3T40 (RPO MD9)

CONDITION:

Vehicles containing HYDRA-MATIC 3T40 (RPO MD9) transaxles may exhibit a harsh clutch engagement (garage shift) when the gear selector is moved from "Reverse" to "Drive" on initial start-up.

CAUSE:

To reduce the harsh garage shift concern ("Reverse to Drive"), the hydraulic circuit at the manual valve was redesigned to allow reverse fluid to exhaust without restricting its flow. The forward clutch stack (625 & 633) was also modified to improve the apply feel during initial engagement.











CORRECTION: (Figures 1, 2, and 3)

Effective April 1, 1993 (Julian Date 091) the thermo orifice (440) and thermo orifice retainer (441) were eliminated from the manual valve (406). (Thermo orifice (440) and orifice retainer (441) will not be removed on A-Car or T-Car applications. Thermo orifice and retainer may be eliminated on A-Car and T-Car at a later date.)

NOTE:
The following is a list of models used only in 1993 A-Car and T-Car applications. (The thermo element orifice and retainer are still present in the following models.)

Models Used Exclusively in A-Cars:
3BYC, 3CMC, 3HPC, 3HCC, 3LCC, 3HXC, 3HTC, 3SWC, 3BZC

Models Used Exclusively in T-Cars:
3HBC, 3PTC, 3JAC, 3PTC, 3HSC, 3TLC

Effective June 22-24, 1993 (Julian Date 152-154) the forward clutch wave plates (625) were replaced with a spring, belleville (625) an additional forward clutch plate (633), a new backing plate (634) (no longer selective), and a new snap ring (617).

SERVICE PART INFORMATION:
The "Conversion Kit Forward Clutch Feel" package comes complete with all the parts necessary to update a HYDRA-MATIC 3T40 transaxle built prior to this mid-year production change. A new manual valve will not be included in the "Forward Clutch Feel" package. The prior manual valve can be used when retainer (441) and thermo element (440) are removed.

Parts are currently available from GMSPO.

WARRANTY INFORMATION:

For vehicles repaired under warranty use:

Labor Operation: K7202

Labor Time: See Applicable Labor Time Guide