Racing Transmission Build - Make It A Muncie

Here, the gear cluster is laid into position in the bottom of the case. There are three different gear ratios that were used in the Muncie, but they are generally put into two groups. The wider ratio 2.52:2.56 First gear is identified by either two ring grooves on the input shaft or the absence of any ring grooves. The close ratio 2.20 ratio cluster is what you want. It has one ring groove on the input shaft. Although you won't use First, the 2.20 cluster has a lower Third gear (1.28 versus 1.46 or 1.48) which is preferable for restarts.

Instead of gaskets, Cook uses silicone sealer on his rebuilds. He says that getting rid of the gaskets cuts out a couple thousandths of spacing, and on an older transmission that can help tighten back up the clearances.

Without First and Second gears, it is possible to install the input shaft onto the main shaft and install both into the case at the same time.

The shafts slide into position in the case from the rear until the mid-plate is tight against the case.

The reverse gears take a lot of abuse because there is no synchronizer ring, and inexperienced drivers will often grind the gears trying to get into reverse. But reverse is rarely used in a racecar and a smart driver can baby the gears. Buying new gears can significantly increase the cost of the transmission, so Cook says he regularly reconditions the reverse gears by carefully resharpening the front of the teeth with a small grinder.

Once the reverse gears are positioned in the tail housing, it is ready to be bolted into place.

After installing the output seal, Cook fabricates two tabs that are held in place with a hose clamp. If something causes the yoke of the drive shaft to bang into the tail housing of the transmission the tabs will keep the seal from coming out, while the hose clamp will also prevent the cast housing from cracking.

On the left is an input bearing for a Muncie. Cook says this bearing costs approximately $80 to replace. On the right is the same bearing for a T10. It is approximately 1/3 the price but is too wide and won't fit a Muncie. Cook, however, fabricates his own spacers to make the T10 bearing work in a Muncie. In addition to being significantly cheaper, the bearing also features rubber shielding that protects the bearing from grit while also preventing leaks.

The front bearing is a press fit. If you try to tap it in with a hammer you stand the chance of damaging the soft synchronizer gears. Instead, Cook uses an air chisel and the bearing literally drops into place.

Finally, the front cover is bolted up.

To work in a two-speed setup, the stock shifter mechanism must be modified slightly. First, the rod connecting to the First/Second shifter mechanism must be removed. Then, you need to tack weld the First/Second lever to the Third/Fourth lever in the location pointed to here. Without doing this, the shifter won't be able to get the transmission into reverse.