3T40 (125/125C) Automatic Transaxle

Transmission ID:

Transmission Identification Label: 3T40

Hydra-Matic 3T40 Transaxle:

Transmission Cutaway View



Hydra-Matic 3T40 (MD9) Automatic Transmission:



The Hydra-Matic 3T40 transmission is a fully automatic transmission used in front wheel drive and mid-engine rear wheel drive vehicles, which provides three forward gear ranges and a reverse.

Shift points are controlled by throttle opening via a throttle cable and a governor circuit.

A Torque converter clutch (TCC) is controlled by a solenoid located inside the transmission assembly. The solenoid is energized by the Electronic Control Module (ECM) through a combination of switches and sensors.

Two oil pressure switches are located inside the transaxle which relay actual gear position to the Engine Control Module (ECM) for use in fuel control and other engine management functions.

Major Components:
^ 4-element hydraulic torque converter.
^ Compound planetary gear set.
^ Dual sprocket and drive link assembly.
^ Three multiple disc clutches.
^ One roller band.
^ Intermediate band assembly.
^ Valve body assembly.
^ Vane type oil pump.
^ 3rd gear oil pressure switch.
^ 2nd gear oil pressure switch (some models only).