True Connections

This month we are continuing with transmission changeovers, and discussing swapping out an automatic for a 4 speed manual. If you need information pulling out your existing automatic, the two previous issues discussed the process in depth. When installing a 4 speed manual such as a Muncie, it’s best to begin by setting up your clutch first. Since the input shaft on a Muncie extends into the back of the crank shaft you will need to install a Bronze pilot bushing by tapping it into the crank. Next you can install the flywheel onto the crank. We usually recommend using new hardware for your flywheel and clutch plates, and always follow the recommended torque specifications. When you purchase your clutch assembly the manufacturer will normally include the pilot alignment tool in order to line up the clutch disc during installation, just make sure you use it, otherwise you will never get your trans to mount up. Once the pressure plate is installed you can install the throw out bearing and clutch fork into the bell housing then mount the bell housing onto the engine.

Next you can install the transmission onto the back of the bell housing. The rear crossmember can now be moved into place which just happens to be the same exact location as it mounted for a Powerglide or TH350 trans. And thanks to the Chevy Gods the transmission yoke and drive shaft length will also be the same. From 1964-1967 the transmission crossmembers do not need to be modified at all. If however you have a 1968-1972 Chevelle or El Camino and you are going to use a factory shifter, there is a small bracket that must be welded to the crossmember to allow the shifter supports to be mounted. If you are going to use an aftermarket shifter then there’s no need to worry about it. Once that is taken care of you can move on to the clutch linkage.

The Z-bar or bell-crank needs to be mounted first by using a ball stud threaded into the block and on the other side next to the frame you will need to mount a bracket that holds another ball stud. On 1964-1967 models that bracket was welded to the frame, while the 1968-1972 models was bolted on. Either version is available in the reproduction market. The next step would be to install the clutch pedals. If you follow the brake pedal up to where it pivots, you will find that it is mounted to a bracket and held in place by a large pivot pin. On one side of the pin you can remove a snap clip, pull the pin out, and drop the brake pedal. To install the clutch pedals it is simply the reverse this procedure, except that the clutch pedal has the pin already mounted on the end of it. While you are installing your new pedals, make sure the nylon bushings on the pin are in good condition and lubricated with general purpose grease. Next, to attach the Z bar push rod to the clutch pedal you will need to cut a hole in the steering column to firewall plate, and install a new dust boot and retainer. Back under the car, the clutch adjusting rod needs to be installed between the Z bar and the clutch fork, and is held in place by a spring connected to the clutch fork on one end and the Z bar on the other. The actual clutch return spring is connected to the Z bar and a small bracket tack welded to the floorboard. The only thing left to do is adjust the clutch to factory specifications and you’re all set. Next month we will go more into depth with the 4 speed shifters.