4T60/440T4/F-7 CODES FOR NEW CHANNEL PLATE & INPUT HOUSING

MODELS/YEARS 1990 CUTLASS CIERA, CUTLASS SUPREME, EIGHTY-EIGHT, NINETY-EIGHT AND TORONADO MODELS EQUIPPED WITH HYDRA-MATIC 4T60 (THM 440-T4) TRANSAXLE (RPO-ME9)

BULLETIN COVERS:

New model codes for a new channel plate assembly that does not have an input accumulator and for a wave plate and extra input clutch plate that has been added to the input clutch. See Figure 1 through 6.

IMPORTANT:

The shift speed charts, minimum and maximum oil pressures and wiring diagrams have not changed. Use the cross-reference chart in Figure 1 to find the previous 1990 model; then reference previous model data listed (oil pressure, wiring diagrams and shift speed charts) to service the new 1990 model. For example, the new 1990 model OWMH will be serviced by the 1990 OBHH model data.

For the new channel plate, input clutch wave plate and input clutch plate, the following parts were modified to eliminate the input accumulator components:

Four instead of three input clutch (steel or reaction) plates (647). The new input clutch plate will assemble between the added wave plate (810) and input clutch (fiber) plate assembly (The new input clutch plates will also be thinner by 0.722mm (0.028") to make room for the added wave plate and input clutch plate). The previous input clutch plates will still be available. Do not mix the previous and new input clutch plates; this will cause a durability concern.

Channel plate (404) will not have the input clutch accumulator bore and components. A wave plate will be added to the input clutch assembly that will replace the function of the accumulator. The new channel plate will also have porting changes that will help ensure that two ports will never be opened simultaneously, which causes distress to the 4th clutch assembly when the shift cable is not set correctly or is kinked or binding. The previous channel plate with the input accumulator bore and components and the new channel plate are not interchangeable. The channel plate with the input accumulator will still be available.

New manual valve (403) will have changes to the valve lands and be reduced 0.25mm (0.010") in diameter for the new porting changes to the channel plate. The previous and new manual valves are not interchangeable. The new manual valve will assemble into the previous production channel plate, but the transaxle will not function because of excessive leakage due to the diff erences in sizes.

New inside detent lever (704) will have the manual link hole location changed for a different "throw" of the manual valve. The previous and new inside detent lever are not inter-changeable even though the parts will physically assemble. The new inside detent lever must be used with the new manual valve and channel plate. The previous inside detent lever must be used with the previous manual valve and channel plate. The identifier for the new Cutlass Supreme inside detent lever is an added square hole. The previous Cutlass Supreme inside detent lever is gold in color. Some of the early new Cutlass Supreme inside detent levers may be gold in color and have the added square hole. The gold color will be discontinued and the square hole will be the only identifier for the new Cutlass Supreme inside detent lever. The previous inside detent lever will still be available for models that just need replacement of the lever for 1987 and prior model years. Input housing (632) has been revised by moving the snap ring groove up 1.50mm (0.059") to make room for the wave plate and extra input clutch plate in the input clutch. The previous and new input housings are not interchangeable because of the differences in clutch pack free play and travel. The previous input housing will still be available.

DATE OF PRODUCTION CHANGE:

All HYDRA-MATIC 4T60 (THM 440-T4) transaxles are built with the new channel plate, input housing (with the wave plate and extra input clutch plate) and new model codes starting January 16, 1990 (Julian Date 016).

SRTA MODEL INFORMATION:

- SRTA models with the new 1990 model codes may not have all the new components listed in this Service Bulletin. These parts include: new input housing with the wave plate and four thinner input clutch plates and the new production channel plate without the input accumulator components.

SERVICE PARTS INFORMATION:

The channel plate assembly packages will contain:

- Channel plate assembly without input clutch accumulator bore

- Valve, manual

Part Model Number Description Year Model Usage

8677252 Channel Plate Asm. -Complete 1990 YDH,YHH,YSH, YTH

8677251 Channel Plate Asm. -Complete 1990 YRH, WDH, WFH, WHH, WJH, WMH, WNH, WPH, WXH

8651903 Pkg. - Input Clutch Housing 1990 All New Models

8675257 Plate - (Waved) 1990 All New Models

8651446 Plate - Input Clutch 1990 All New Models

8668991 Pkg. Lever - Inside Detent 1985-90 All New Models Except (for new channel plate) Cutlass Supreme with new service or production channel plate

8668992 Pkg. Lever - Inside Detent 1985-90 Cutlass Supreme only (for new channel plate) that has new service or production channel plate

Parts are currently available from GMSPO.

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.