3-2 DOWNSHIFT BUMP 440T4 TRANSAXLE,NEW P/N

VEHICLES AFFECTED: Some 1985 THM 440-T4 Model BA, BC,CM & CP Transaxles

Some 1985 THM 440-T4 'BA', 'BC', 'CM' & 'CP' model transaxles (refer to Figure 1), may exhibit a 3-2 downshift bump. This condition may be most prevalent during a part-throttle downshift with the air conditioner operating. A slight transaxle tie-up condition which shakes or rattles the instrument panel during the downshift may also be experienced.

When servicing any 1985 THM 440-T4 'CM' & 'CP' model for a 3-2 downshift bump, order and install service package part number 8646951.

Service package part number 8646951 contains one each of the following:

3-2 Control valve spring 1-2 servo boost valve Instruction sheet

When servicing any 1985 THM 440-T4 'BA' or 'BC' model for a 3-2 downshift bump, order and install service package part number 8646953.

Service package part number 8646953 contains one each of the following:

3-2 Control valve spring Instruction sheet

Refer to Figure 2 of this bulletin and the appropriate Service Information Manual for proper installation procedures. Models 'BA', 'BC' & 'CP' are 1985 models while 'CM' is a 1985-1/2 model. There are differences between the 1985 and 1985-1/2 models which are explained in Product Service Bulletin 85-7-139.

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.