Muncie 4-Speed Transmissions: How to Rebuild & Modify

The Muncie 4-speeds (M20, M21, and M22) are some of the most popular manual transmissions ever made and continue to be incredibly popular. The Muncie was the top high-performance manual transmission General Motors offered in its muscle cars of the 1960s and early 1970s. It was installed in the Camaro, Chevelle, Buick GS, Pontiac GTO, Olds Cutlass, and many other classic cars. Many owners want to retain the original transmission in their classic cars to maintain their value.

Transmission expert and veteran author Paul Cangialosi has created an indispensable reference to Muncie 4-speeds that guides you through each crucial stage of the rebuild process. Comprehensive ID information is provided, so you can positively identify the cases, shafts, and related parts. It discusses available models, parts options, and gearbox cases. Most important, it shows how to completely disassemble the gearbox, identify wear and damage, select the best parts, and complete the rebuild. It also explains how to choose the ideal gear ratio for a particular application. Various high-performance and racing setups are also shown, including essential modifications, gun drilling the shafts, cutting down the gears to remove weight, and achieving race-specific clearances.

Muncie 4-speeds need rebuilding after many miles of service and extreme use. In addition, when a muscle car owner builds a high-performance engine that far exceeds stock horsepower, a stronger high-performance transmission must be built to accommodate this torque and horsepower increase. No other book goes into this much detail on the identification of the Muncie 4-speed, available parts, selection of gear ratios, and the rebuild process.