UNIT REPAIR TRANS. THM 440T4 3-2 SHIFT CONTROL VALVE CHANGE

THM 440-T4 (ALL 1985 AND 1985 1/2 MODELS)

Hydra-matic is releasing eight new 1985 1/2 THM 440-T4 models to replace the 1985 models as indicated in Figure 1. The 1985 1/2 models have a redesigned control valve assembly with a new 3-2 line control valve that makes the 3-2 downshift more responsive to throttle position. The oil passages in the control valve assembly, channel plate, spacer plate, and gaskets have also changed.

1985 MODEL . . . replaced by . . . 1985 1/2 MODEL AC . . . . . . . . . . . . . . . . AF AY . . . . . . . . . . . . . . . . AM BC . . . . . . . . . . . . . . . . BR BU . . . . . . . . . . . . . . . . BV BX . . . . . . . . . . . . . . . . BW CP . . . . . . . . . . . . . . . . Cm CW . . . . . . . . . . . . . . . . CN HT . . . . . . . . . . . . . . . . HJ

FIGURE 1 1985-1985 1/2 MODEL IDENTIFICATION

Service Parts Information

The 1985 1/2 model control valve assembly, spacer plate, and gaskets will not service the 1985 model. Until 1985 1/2 model part number listings are available, service replace parts can be ordered through GMWDD by description (part name). Refer to Figure 2 for correct transaxle model identification information.

Unit Repair Information

The current Service Information Manual describes the 1985 models and will provide enough reference material to cover authorized dealer repairs for 1985 1/2 models. The exception is check ball locations. Refer to Figure 3 for control valve assembly and Figure 4 for channel plate check ball locations for the 1985 1/2 models.

Unit repair information for 1985 1/2 models will be provided in a bulletin.

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.