SERVICE INFORMATION ON 4T60-E TRANSAXLE W/3.4 TWIN DOHC

SUBJECT: SERVICE INFORMATION ON THE NEW HYDRA-MATIC 4T60-E TRANSAXLE MODEL

MODELS/YEARS: 1991 CUTLASS SUPREME WITH HYDRA-MATIC 4T60-E AND 3.4L TWIN DOHC ENGINE (VIN X)

This bulletin covers service information on a new HYDRA-MATIC 4T60-E transaxle model for the 3.4L twin DOHC engine (VIN X) used in 1991 Cutlass Supreme. The HYDRA-MATIC 4T60-E is a new transaxle model with electronic shift controls. The HYDRA-MATIC 4T60-E Service Replacement Transmission Assembly (SRTA) program will service the 1CWW model. The SRTA model, complete overhaul and on-car service parts can be ordered for the HYDRA-MATIC 4T60-E model from your local General Motors Service Parts Operation (GMSPO) Parts Distribution Center.

COOLER FLUSHING:

IMPORTANT: Cooler flushing MUST be performed whenever a transmission/ transaxle is removed for service. It is essential to flush the cooler for SRTA installation, major overhaul, in any case of pump or torque converter replacement, or when fluid contamination is suspected. Use Kent-Moore tool J 35944 to flush the cooler.

HYDRA-MATIC 4T60-E TRANSAXLE IDENTIFICATION INFORMATION:

Transaxle identification information shown in Figure 1 will assist you in selecting and ordering the correct SRTA unit from your local Parts Distribution Center.

UPDATED SHIFT SPEED CHART: (Figure 2) --------------------------------------- Reference the updated shift speed chart when servicing a 1CWW model. (Please update your Service Manual accordingly). See Figure 2.

NEW HIGH TORQUE GEAR SET: (Figure 3 - 5) ------------------------------------------ A new high torque gear set is used only in the 1CWW model. This new gear set includes: a new input carrier, reaction carrier, final drive sun gear and final drive carrier. For this change to be implemented, the following parts were modified:

- New reaction carrier needies, pinions, pinion shafts and lube grooves added to the carrier to increase lubrication through the needles. The lubrication flows into the lube groove slots in the carrier between the washer and the carrier, then through the needles. This helps get lube to the needles under high torque situations. The identifier is a wide green band around the outside of the carrier.

- New input carrier needles, pinions, pinion shafts, washers and lube grooves added to the carrier to increase lubrication through the needies. There used to be a bronze and a steel washer on each side of each pinion. Now, there are two new steel washers on each side of the pinion that have three scallops or lube openings to help increase lube flow through needles. The identifier is a wide green band around the outside of the carrier.

- New final drive carrier arid sun gear that have phosphate coated pinions and sun gear to reduce spalling arid pitting under high torque situations. The identifier for the high torque 3.06 ratio final drive carrier is a blue dot and pink dot located on the carrier by one of the pinions. The final drive sun gear is a darker black than the standard 3.06 ratio sun gear.

NOTICE: Use only the new high torque gear set parts when servicing a 1CWW. Durability concerns could result if non-1CWW gear set parts are used. The new gear parts can service most previous model input and reaction carriers that have the wider sprag and lube dam. Reference Dealer Technical Bulletin 87-T-09A. The new 3.06 sun gear arid final drive carrier can service most previous 3.06 ratio models back into the 1988 model year. Reference Dealer Technical Bulletin 88-T-91.

HYDRA-MATIC 4T60-E SRTA PART NUMBER:

IN THE INTEREST OF CUSTOMER SATISFACTION, SRTA MODELS SHOULD ONLY BE CONSIDERED WHEN THE PROJECTED COST OF REPAIR EXCEEDS THE COST OF A SRTA REPLACEMENT.

SRTA SRTA Model Part # Description ----- ------- --------------------------------------- 1CWW 8651961 3.4L Twin DOHC W-car 4T60-E Transaxle Model

SERVICE PARTS INFORMATION:

Part Number Description Model Usage ------- ------------------ ----------- 8679001 Carrier Assembly - 1CWW Reaction Complete

8679000 Carrier Assembly - 1CWW Input Complete

8651912 Carrier Assembly - 1CWW Differential/Final Drive Complete

8679567 Gear - Final Drive Sun 1CWW

Pan numbers are accurate at the time of printing and subject to change. Refer to the latest GMSPO Parts Catalog for the part number of the SRTA model listed.

ALL parts listed are expected to be available on 03-15-91. Until then normal part orders will not be accepted by GMSPO. Only verifiable emergency VIP orders will be accepted. SPO 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 canceled as incorrectly ordered while the 400 control is in place.

General Motors bulletins are intended for use by professional technicians, not a "do-it-yourselfer". They are written to inform those technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions and know-how to do a job properly and safely. If a condition is described, do not assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See a General Motors dealer servicing your brand of General Motors vehicle for information on whether your vehicle may benefit from the information.