Aisin Warner; Toyota A40D

Transmission general data

The legendary family of automatic transmissions А40D (А42, А43, А44, А45, A46) was developed by Aisin Warner and belongs to Toyota Group. They have been used since 1985 as a 3-speed transmission named as 03-55(А40), and since 1979 as a 4-speed transmission for RWD cars with the engine capacity from 1.6 up to 3 liters. The 4-speed gearbox has D letter in its name and an additional clutch "Overdrive" in the 4-speed in the design.This gearbox is mainly used in right-hand drive cars (Hiace, Liteace etc.) and in other Toyota RWD cars in Asia. The modification with some other valve body AW03-70 .../72 or AW371, AW372 was produced for other markets. This modification was installed on Suzuki, Mitsubishi, etc. The most popular models of this family in repair services A44DE, 46DE \F (Previa), A42DE, 43DE were updated and released in 2000. This transmission is an example of a standard structural design, which was widely used by ZF in 4HP22 and by American Ford in its A4LD. The design of almost all rear-driven gearboxes ensures uniform wear-out of all units and solid safety coefficient of gearbox components, therefore these gearboxes easily travel 500 thousand kilometers. Earlier the repair process mainly involved transmission replacement.

Technical issues and repair guidelines

Typical issues of the А40 transmission are mainly caused by the the unit's ageing:

- Damaged torque converter lockup clutch. The damage of the lockup frequently causes heavy vibrations, resulting in the seal damage, then leading to issues with the pump liner and the pump itself.

- Worn-out friction components in Direct- Forward and Reverse packs. Old cars usually require replacement of these frictions.

- Rubber elements become hard with time and overheating causes the wear of rings, leading to pressure supply deficiency in packages and burning of friction components.

Overhauls mainly include the transmission reassembly and cleaning procedures accompanied by spare parts replacement – namely, worn-out brake blocks, frictions and gaskets with seals. All friction components are usually replaced during the overhaul of transmissions in cars with high mileage and burnt oil.The second most commonly replaced component in this transmission is the Low reverse clutch. Major repairs of hard parts mainly take place when the pump bushing (and leaking seal) gets damaged by the torque converter lockup clutch.