There's an important component standing between your engine and your drive wheels: the transmission. Inside that metal case is a bewildering array of gears, bearings, seals, and more. The automatic transmission is a miracle of modern engineering, but it can also be a source of trouble. If your transmission breaks down you're not going anywhere, and if it's just not working properly, your car will never realize its performance potential. In this book, expert mechanic and drag racer Cliff Ruggles demystifies the popular GM 700-R4 and 4L60 automatic transmissions. Keeping the enthusiast in mind, Ruggles explains the history of these transmissions, presents critical identification guidelines, and leads the reader through the complete disassembly, repair and upgrade, and assembly processes. DIY-ers will learn how to test their transmission to ensure its proper operation before installing it in the car. This book includes information about high-performance modifications, both from the factory and the aftermarket. These include internal parts and external components such as shift kits and torque converters that will help you make your transmission perform at its best. It also covers common installation issues such as mounting, shifters and linkages, wiring harnesses, and more, and includes a special section by Ro McGonegal on swapping these transmissions into earlier performance and musclecar chassis.