- Home >
- Muncie 4-Speed Transmissions: How to Rebuild and 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.
Pages: 144
Size: 8.5 X 11 (inches)
Format: Paperback
Illustrations: 451 color photos and charts
Publisher: CarTech
ISBN: 9781613251065
Product Code: SA278
Acknowledgments
Introduction
What is a Workbench® Book?
Chapter 1:
History and Evolution
Happy Accidents Create the Muncie
Muncie Design Changes
Available Gear Ratios
Chapter 2:
Muncie 4-Speed Identification
Muncie RPO Codes
Main Case Casting Numbers
Serial Numbers
Main Cases
Service Cases and Transmissions
Extension Housings and Sidecovers
Midplate Castings
Ratio Identification
Hardware and Tags
Chapter 3:
How Muncie 4-Speeds Work
Forward Gears
Reverse Gears
Lack of Front Seal
Design Features
Diagnosing Common Problems
Shifter Considerations
Chapter 4: Inspection and Repair
Cleaning
External Case Components
Gears, Synchros and Shafts
Bearings and Bearing Surfaces
Chapter 5: Rebuilding Your Muncie
Muncie Rebuild Kit
Workflow Process
Chapter 6:
High-Performance Muncies
Auto Gear Equipment
High-Performance Gearsets
Muncie Design Features
Road Racing and Endurance Use
Chapter 7:
Advance Adapters 4x4 Conversion Kit
Mainshaft Assembly
Maindrive Inspection
Gearbox Assembly
Chapter 8:
Parts Resources
Group A: Mainshaft and Extension Housing
Group B: Maindrive and Retainer
Group C: Countershafts and Case
Group D: Internal Shift Linkage
Group E: Service Kits
Appendix:
Original Muncie Patent
Source Guide
Paul Cangialosi

Paul Cangialosi is the owner, proprietor, and top wrench at Medatronics Corporation and 5speeds.com in Tequesta, Florida. He first started working on cars at the age of 12 and his automotive passions have burned bright ever since. He has pursued his passion for manual transmissions for nearly 30 years. Today, Cangialosi's businesses offer 12 different rebuild kits and 6 new transmissions, as well as rebuilding, fabricating, and design services for high-performance manual transmissions.