Description

The automatic transmission is a combination of a 3-element torque converter and triple-shaft automatic transmission which provides 4 speeds forward and 1 reverse. The entire unit is positioned in line with the engine.

Torque Converter, Gears and Clutches
The torque converter consists of a pump, turbine and stator, assembly in a single unit. The torque converter is connected to the engine crankshaft so they turn together as a unit as the engine turns. Around the outside of the torque converter is a ring gear which meshes with the starter pinion when the engine is being started. The entire torque converter assembly serves as a flywheel while transmitting power to the transmission mainshaft. The transmission has three parallel shafts, the mainshaft, countershaft and sub-shaft. The mainshaft is in line with the engine crankshaft.
The mainshaft includes the clutches for 1st, and 2nd/4th, and gears for 3rd, 2nd, 4th, reverse and 1st (3rd gear is integral with the mainshaft, while reverse gear is integral with the 4th gear).
The countershaft includes the 3rd clutch and gears for 3rd, 2nd, 4th, reverse, 1st and parking. Reverse and 4th gears can be locked to the countershaft at its center, providing 4th gear or reverse, depending on which way the selector is moved. The sub-shaft includes the 1st-hold clutch and gears for 1st and 4th.
The gears on the mainshaft are in constant mesh with those on the countershaft and secondary shaft. When certain combinations of gears in the transmission are engaged by the clutches, power is transmitted from the mainshaft to the countershaft via the sub-shaft to provide I D4~, D3 , ©, 0 and R

Hydraulic Control
The valve body assembly includes the main valve body, secondary valve body, regulator valve body, servo body, modulator valve body, lock-up valve body, and governor body, through the respective separator plates. They are bolted on the torque converter housing.
The main valve body contains the manual valve, 1-2 shift valve, 2-3 shift valve, 3-4 shift valve, 3-2 timing valve, 4th exhaust valve, relief valve, and oil pump gears.
The secondary valve body contains the 4-3 kick-down valve, 3-2 kick-down valve, 2-3 orifice control valve, 2-1 timing valve, Clutch Pressure Control (CPC) valve, servo control valve, reverse control valve, and governor cut valve. The regulator valve body contains the pressure regulator valve, lock-up control valve, torque converter check valve, and cooler relief valve.
The servo body contains the servo valve which is integrated with the reverse shift fork, throttle valves A and B, 2/3-4 orifice control valve, and accumulators.
The modulator valve body, which is bolted on the servo body, contains the modulator valve.
The lock-up valve body contains the lock-up shift valve and lock-up timing valve B, and is bolted on the secondary valve body.
The governor body is bolted on the torque converter housing near the differential.
Fluid from the regulator passes through the manual valve to the various control valves.

Lock-up Mechanism
In D4 and D3 position, in 2nd, 3rd and 4th, pressurized fluid is drained from the back of the torque converter through an oil passage, causing the lock-up piston to be held against the torque converter cover. As this takes place, the mainshaft rotates at the same speed as the engine crankshaft. Together with hydraulic control, the ECU optimizes the timing of the lock-up mechanism.
The lock-up shift valve controls the range of lock-up according to the lock-up control solenoid valves A and B, and throttle valve B. The lock-up control solenoid valves A and B are mounted on the torque converter housing, and are controlled by the ECU.