This Muncie is in the final...
This Muncie is in the final stages of its conversion to a lightweight two-speed racer. Although it isn't as popular as the T10 among Saturday night racers, when properly prepared, the Muncie can make a capable racer quite economically.
It may not be as popular in Saturday-night stock car racing circles as the Borg Warner T10, but the classic Muncie four-speed manual transmission can be made into a capable racer. Like the T10, the Muncie is compact, uncomplicated, capable of withstanding a moderate amount of abuse and easily modified.
It is the modification part of that list that pricked our ears when gear specialist Jim Cook of Jim Cook Racing Transmissions told us he was modifying a Muncie for a short-track racer. Cook's race-ready Muncies go through a lightening program that cuts over five pounds of rotating weight by eliminating First and Second gears. Third gear becomes the pit and restart gear while Fourth gear at 1:1 is for racing. Other modifications are also made to help the transmission live under racing abuse and even break the Muncie's annoying habit of popping out of gear at precisely the wrong times.
The Muncie--which is also sometimes referred to as the Rock Crusher--was produced and installed in GM vehicles between 1963 and 1974. That wide time frame means a lot of Muncie transmissions were built, and a lot are still available out there. But, it also means that the design is over 30 years old, and while new replacement parts are still being produced, they aren't in big demand. In effect, the case and core components of the Muncie are cheap, but some select replacement parts--namely bearings--can be quite expensive. But Cook says that by intelligently swapping out components a race-ready Muncie can be built for around $500, which is just under half what a T10 would cost. Very few components from the T10 will work on the Muncie, but Cook has designed adaptors to use T10 bearings when the stock Muncie components are either hard to find or too expensive.
When built properly, Cook says a Muncie two-speed can reliably handle 450-500 horsepower, making them a realistic alternative for many different racing classes. If you decide to hunt for one in a junkyard, just remember that they appeared between 1963 and 1974 in several GM vehicles, but your best bets are Chevy performance cars like Novas and Camaros as well as the bigger cars.
The cases of the Muncie, Saginaw and T10 transmissions are almost indistinguishable to the untrained eye, and they are not interchangeable. Thankfully, however, there are easily identifiable features you can use to determine what you are looking at without hunting around for identification numbers. The Saginaw is the only one of the three that has the reverse shifter mechanism on the case. It is on the tail housing on the other two. On the Saginaw, it is easy to see because all three control rods on the shifter mechanism connect to the main case, while on a Muncie and T10, just one of the three control rods connects ends at the tail housing. The T10 and Muncie are identifiable because the bottom of the side cover on the T10 is curved while the bottom on a Muncie is straight.
If you're a racer who is on a budget (and who isn't?) a modified Muncie may be just the ticket to save you some money. An extra $500 will go a long way.
Gear specialist Jim Cook begins...
Gear specialist Jim Cook begins by modifying the side cover and shifter forks to work properly after First and Second gears have been removed. Here, you can see that the shifter fork on the left side has been removed. The hole is plugged with a standard one-inch freeze plug. Cook also drills a hole in the cover and installs a bolt to give the shifter mechanism a positive stop after the shifter fork has been removed.
Cook also cuts the shifter...
Cook also cuts the shifter mechanism. Here, the stock unmodified lever is placed on top so you can see the difference.
Here is what becomes unnecessary...
Here is what becomes unnecessary when First and Second gears are removed. That's approximately five pounds of weight you are looking at, and most of it is rotating weight. Third gear becomes the pit/restart gear, and Fourth, which is a 1:1 ratio, is the race gear.