Repairing a Chevy Muncie four-speed transmission involves cleaning it thoroughly, carefully inspecting its parts, obtaining replacement parts and tools, and possibly installing a new gear shifter. The process is usually inexpensive and doesn't require special tools.
The ease of repairing a Muncie transmission makes it a good do-it-yourself project. A thorough rebuild of the transmission is often a good idea, as this prevents frequent repairs, which are likely in old transmissions. A repair or rebuild requires a gear rebuild kit and a new shifter and shifter installation kit if you need to replace the gear shifter.
A thorough cleaning of the transmission is required, owing to the years of accumulated oil and dirt in an old four-speed such as the Muncie. Carefully inspect every part of the transmission during repairs. A reliable guide or manual is helpful during this process. Order a new part if the old one isn't satisfactory; for instance, fresh bearings and synchronizers can improve the drivability of the vehicle. As of 2015, there are a number of companies that offer replacement options for various components, some of which are much stronger than the originals.
Use a quality, high-temperature grease for adhesion, as this saves repairs down the road. Use new external shifter shaft seals to resolve leaks in the transmission. During installation of a new gear shifter, make sure you have the shift gear orientation correct for each gear, or your first gear may be second, your third could be fourth, and so on.