A new style 1-2 band assembly will be used in production of all HYDRA-MATIC 4T60 (THM 440-T4) transaxles. The area on the new 1-2 band assembly where the 1-2 band apply pin engages is almost twice as wide as the previous style. This increased area makes for a larger "target" for the 1-2 band apply pin and eliminates the need for the 1-2 band stop.
The 1-2 band stop was used to keep the 1-2 band assembly from shifting off location. If the band shifts off location, this would cause the 1-2 band apply pin to miss the band while stroking, creating a loss of drive. See Figure 1.
The new style 1-2 band assembly can be used to service past model cases, but the 1-2 band stop must be removed.
DATE OF PRODUCTION CHANGE:
The new 1-2 band assembly was put in production starting January 16,1990 (Julian Date 016).
When the supply of previous style 1-2 band assemblies is depleted, the new 1-2 band assembly will be the only style available.
SERVICE PARTS INFORMATION:
Part Number Description Model Year/Model Usage ----------- ----------- ---------------------- 8668984 Pkg. 1-2 Band Assembly 1984-90 All - 1-2 Band Assembly - Instruction Sheet
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.