A/T - New 3RD Fluid Reroute of 3-2 Downshift Fluid

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NUMBER: 90-T-19

CORP.REF.NO. 977142R

DATE: October 1989

SECTION: 7A


SUBJECT:
NEW PRODUCT INFORMATION (3RD FLUID REROUTE)

MODELS/YEARS:
1990 CUTLASS CALAIS AND CUTLASS CIERA








BULLETIN COVERS: (Refer to Figures 1 thru 4)

New 3rd fluid reroute of 3-2 downshift fluid for a more consistent 3-2 downshift feel at high altitude areas. This consists of a new 3rd clutch fluid switch with external bracket, and modification of the control valve assembly and auxiliary valve body and gasket to allow a faster flow of 3rd signal fluid to the 3rd clutch fluid switch during 3-2 downshifts while maintaining 3rd clutch fluid to the orifice control valve.

These new castings, with appropriate machining differences, are also used on all other models. The auxiliary valve body gasket revision applies to all auxiliary body gaskets.





DATE OF PRODUCTION CHANGE: (Refer to Figure 5)

The new 3rd clutch fluid switch, control valve assembly, auxiliary valve body and gasket went into production for OBUC, OBYC, OBZC HYDRA-MATIC 3T40 (THM 125C) transaxles Start of Production 1990.

SERVICE PROCEDURE:

Do not attempt to use the new 3rd fluid reroute components on any other prior or current model year HYDRA-MATIC 3T40 (THM 125C) transaxle since these parts are not interchangeable, or a change in shift characteristics and/or unit durability will occur.

SERVICE PARTS INFORMATION:

Whenever ordering parts for models equipped with the new 3rd fluid reroute, refer to the following part numbers.

Part Number Package Discription

8666385 BUC Control Valve Assembly with
8666384 BYC, BZC Auxiliary Valve Body

8666380 Auxiliary Valve Body Gasket

8666603 3rd Clutch Fluid Switch with Bracket

Parts are expected to be available on 11-31-89. Until then, normal part orders will not be accepted by GMSPO. Only verifiable emergency VIP orders will be accepted. GMSPO will make every effort to obtain parts. All parts will be placed on 400 control to waive VIP surcharges. However, the part will be shipped premium transportation at dealer's expense. All other order types will be cancelled as incorrectly ordered while the 400 control is in place.

SERVICE MANUAL REFERENCE:

Whenever servicing any HYDRA-MATIC 3T40 (THM 125C) (MD9) transaxle, refer to the procedures outlined in the Unit Repair Section of your Service Manual.