Overhaul - Ax4S Automatic Transmission: Description

The AX4S combines an automatic transaxle and differential into a single unit designed for front wheel drive vehicles. The transaxle is an electronically controlled, fully automatic unit with 4 forward speeds, one Reverse, Neutral and Park. Shift control solenoids provide gear selection and are controlled by the EEC-IV or EEC-V microprocessor. For additional information on the EEC-IV or EEC-V system, refer to TESTS W/CODES - EEC-IV or EEC-V article in ENGINE PERFORMANCE section.

The AX4S has two planetary gear sets and a combination planetary/differential gear set. Four multiple-plate clutches, two band assemblies, and two roller (one-way) clutches act as friction elements for operation of the planetary gear sets. See Fig 1 .

A lock-up torque converter couples the engine output to the planetary gears and overdrive unit. This is done by a chain which connects the drive and driven sprockets. The converter lock-up is controlled through the EEC-IV or EEC-V system. A piston plate clutch, inside converter, is activated through Torque Converter Clutch (TCC) solenoid by the PCM and valve body hydraulic pressure.

Fig 1: Identifying Transmission Components

Courtesy of FORD MOTOR CO.