Mopar Four Speed Transmission Rebuild - Four Gear Freshen

OK, now you are ready for main shaft assembly. It's just the reverse of disassembly. But before you start sliding all the parts back onto the shaft, be sure to smear high-temp grease on each of the machined surfaces that the gears/sliders ride on.

Check/replace the driveshaft yolk bushing before replacing the tailshaft seal.

You might need an extra hand here. Install the main shaft into the tailhousing by wiggling the bearing into place while holding the snap ring open. Now is also a good time to place the tailhousing gasket in place, so you don't forget it when you slide the main shaft into the case.

The 3-4 slider slips on next. The main and input shafts are now ready to be installed into the case.

The countershaft has a long spacer that separates the double set of roller bearing that support each end of the cluster gear. Make sure the key slot is toward the rear.

Here's a tip that will save you some frustration. As soon as you are finished cleaning the case, glue the cluster gear thrust bearings to the inside of the case with some adhesive-type silicone.

This next step is one that can test your patience and even be a little intimidating, but it's really not too tough. There are two sets of roller bearings supporting both ends of the cluster that are separated by a spacer. Using regular high-temp wheel bearing grease, stick the first set into the end of the cluster and then push them far enough down with the spacer to make room for the next set. Put in another set of rollers followed by another spacer. Be generous with the grease. Make certain to put the long spacer in behind the first set before you grease the rest of the rollers into the other end. If you are using a new countershaft, cut the old one to the same length as the cluster and push it into the cluster so that it's flush on both ends. This will hold the bearings in place while you are installing everything into the case. Then, you can use the new countershaft to push out the old, and everything will stay put. If you are reusing your old shaft, slide it into place after the bearings are greased in just to make sure everything is in place. Then, slowly pull it out and carefully put the cluster in a freezer for a while. The extra cold grease should hold the bearings in place while you are juggling the cluster and main shaft in the case.

The input shaft has just one set of rollers. Grease them in place the same as the others, and then tap the input shaft partway into the case. You may need a little extra room to line up the main shaft. Once the main shaft is in place, you can install the snap ring and tap it all the way in.