February 10, 2013


With all the damaged gears replaced, the transmission rebuild was complete with only the gear shift box needing to be attached. I started looking into installing the transmission case back into the tractor and realized that if this "fix" was going to last a long time then a paint job was in order.

Wall-E in need of some fresh paint

Our weird winter weather cooperated and there were several mild days in which I was able to paint the tractor frame. I took the moderately sized parts into a heated space and painted them, particularly the transmission case and eventually the final drive parts.

Transmission case is in place.

It was relatively simple to get the transmission housing into place and the four studs on the front lined up and through the holes on the cross-member. Lock washers and nuts were quickly installed and everything snugged up.

Transmission case - a side view

Next came the transmission-case-to-frame bolts. The originals were worn and since I couldn't find the right length bolts at any of our local hardware stores, I called on Zimmerman Oliver-Cletrac to ship me more parts including a new cover for one of the final drives as well as a few other parts for the final drives.

An "inside" look at the transmission case to cross-member studs.

Tightening the nuts on the case to cross-member studs was a bit difficult as there are several rail road ties under the tractor and everything is supported so contorting my body to get under and into a position in which to turn the wrench was a challenge.

Tightening the rest of the stud nuts

The next step is to install the bolts that hold the transmission case to the frame. After that comes the installation of the differential, an assembly which allows each side of the tractor to move independently.

Time to Work on the Final Drives

While I waited for the parts to arrive, I got both final drives disassembled. As with several of the nuts on this tractor, the final drive "trunnion" nut has a flange on it that gets bent into a grove so that it can not come off when in use. First, I drilled out the bent section of the flange, and then got out a really big wrench. With a helper (a length of pipe large enough to fit over the wrench and act as a handle extension), we managed to remove the nut.

Removing the trunnion nut

A trunnion is a pin or pivot on which something can be rotated and that is exactly what this part does. The trunnion and trunnion nut hold the gear and hub assembly in place and the gear/hub assembly is what holds the "wheel" onto the tractor and allows it to rotate.

Removing the trunnion

The part that is about to fall off is the trunnion. It holds everything in place and the bearings allow the gear/hub assembly to rotate.

As I continue to work on rebuilding Wall-E, I continually discover that one side of the tractor suffered significant damage that needs repair while the other side just needs to be cleaned up. One of the gear/hub assemblies (the one in the photo) is just fine and all it needs is to have its four studs reinstalled. However, the hub on the other side has at least one crack on the housing for each of the 10 studs and one large chip.

Removing the hub/gear assembly

I took the damaged hub into the machine shop and the rivets were ground out so that I could send the gear back east where the guys at Zimmerman Oliver-Cletrac could mount my gear on a new hub casting and send it back. That is one way to save some money since I only needed a new hub, not the whole assembly.

View of the back side of the gear/hub assembly.
You can see the rivet at about 11:30 and the ring marking the difference between the hub and the gear.

Next came a lot of cleaning, and then the removal of the bearings and races. One thing we learned from the machine shop is how to remove races. You weld them. I know, I kind of freaked when I heard that too, but you put a significant amount of weld on the race itself. That heats it up causing it to loose its temper and become soft. When the welded on metal cools, it contracts and shrinks. Once it's cool, it just falls out.

Just need to remove the bearing on the lower shaft and the race in the upper hole.

I've also learned how to pack bearings with grease and install new races effectively. The new "packed" bearing in the photo below is covered in plastic to keep it clean.

New Bearing on shaft and new race installed.

Before they are mounted to the transmission case, the gear/hub assemblies need to be installed. Also the differential and steering components need to be installed in the rear of the transmission case.

two painted final drives ready for the gear/hub assemblies to be installed

As I continue to put things back together, I continue to find things that need replacing. One of the cover plates has a significant amount of wear on the lower hole and the oil seal does not fit snugly. Instead of packing it with a material like Lock-Tite, I decided to order a new cover.

Final Drive Cover Plate

Another part on the order list is one of the pinions. This pinion is on the main drive shaft and transfers power from the differential to the gear/hub assembly that I've been working on. I've also decided to replace both trunnions and trunnion nuts.

Drive Shafts: upper shaft with pinion gear and bearings installed; lower shaft has damaged pinion gear.

Close up of the pinion gears.