Mitsubishi F4A33-1

Transmission general data

Thsi family of automatic transmissions is not complicated and quite reliable solutions based on the KM170. Thanks to their simplicity and durability these transmissions found application even on American cars Dodge, Plymouth. The 4-speed automatic transmission F4A33-1 was designed in 1991 for FWD cars of business class with engine capacities from 2.0 up to 3 liters. In most cases, it is installed on Hyundai Sonata. Mitsubishi installs its own version of this gearbox on models 3000 GT, DIAMANTE, ECLIPSE. For AWD cars the modification of this gearbox is named as W4A32/ W4A33.

Technical issues and repair guidelines

Overhauls of these transmissions are triggered by two main reasons: fluid leakages via the damaged pump seal and issues with gear shifting. Generally, the leaking pump seal is a sign that the torque converter (TC) has been operating with a worn-out lock-up and vibrations for a long time leading to the damage of bushings and seal. Overhauls of these transmissions are usually performed when the car reaches high mileages and consist of reassembly and repair of the TC unit and filter replacement. Specialist always perform the repair of TC, valve body reassembly in half of the cases with check and change of solenoids and wiring. It is also required to replace brake bands if the transmission operates for a long time with burnt fluid. The long-term operation with worn-out torque converter may lead to the damage of seal and pump bushing. As a result, the pump bushing may be replaced. Vibrations may have a negative impact on the pump, therefore specialists have to order a complete kit of bushings for these transmissions.

Overdrive frictions are frequently replaced. Specialist assume that the main reason is related to poor design of an old O.D. piston. In new modifications, this piston has an updated configuration. Usually Direct-Forward ffrictions wear out because they are highly loaded. Solenoids are quite reliable, but when problems occur they are mainly caused by circuits of solenoids (solution –cleaning of contacts). The design of this gearbox is similar to the KM170. After proper reassembly, these gearboxes easily operate for several years until the next overhaul.