This comprehensive Workshop Service Repair Manual provides in-depth technical information for the overhaul of Mitsubishi F4A20 series automatic transmissions, specifically models F4A21, F4A22, and F4A23. The manual covers a wide range of vehicles equipped with these transmissions, including popular models like the Colt, Colt Vista, Eclipse, Expo, Galant, Laser, Mirage, Summit, Sigma, Summit Wagon, and Talon. The manual covers the years 1990 to 1994, offering detailed guidance on the repair and maintenance of these transmissions. This manual is an essential resource for mechanics, technicians, and DIY enthusiasts seeking comprehensive information on the overhaul process for Mitsubishi F4A20 series automatic transmissions. It provides step-by-step instructions, diagrams, and specifications to ensure successful repairs and restorations.

The Mitsubishi F4A20 series automatic transmission gearbox, encompassing the F4A21, F4A22, and F4A23 variants, is a robust and reliable transmission system designed for various Mitsubishi passenger cars. These gearboxes are known for their smooth shifting, durability, and fuel efficiency. The F4A20 series transmissions utilize a four-speed planetary gearset, featuring electronically controlled hydraulic pressure for precise gear changes. This sophisticated design ensures seamless acceleration and smooth cruising, enhancing the overall driving experience. The transmission incorporates a torque converter, efficiently transferring engine power to the wheels while minimizing engine braking and providing a comfortable ride.

Beyond its core functionality, the F4A20 series transmissions benefit from numerous advanced features. These include a lock-up clutch, which directly connects the engine to the transmission during high-load conditions, improving fuel economy. The system also incorporates a sophisticated electronic control unit (ECU) that monitors various parameters like engine speed, vehicle speed, and throttle position to optimize shifting characteristics. This ensures optimal performance and fuel efficiency across various driving scenarios. While the F4A20 series transmissions are known for their reliability, they are not immune to wear and tear over time. Periodic maintenance is crucial, including fluid changes and filter replacements, to ensure optimal performance and extend the transmission's lifespan. An overhaul, a comprehensive cleaning and replacement of worn components, is often necessary to restore a transmission back to factory specifications in cases of significant wear or damage.