Assembly Instructions - Page 12, Step 12
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This step assembles the front differential. There are several things to pay attention to, but it's pretty simple for any experienced hobbyist.
Step 12
Before starting assembly of the front differential, lightly grease the inside of the gear diff case.
Find the spring that is shown in the top position in the picture below. The spring on the bottom is for the front suspension, do not use this spring for this step.
Get the brass gears from your parts box onto the spring, as shown below.
Move the gears into position as instructed in the manual, then slide the metal pin into place.
Slide the large red o-rings into place.
When removing the large plastic gears for the front gear diff (#73403-5), use a hobby knife to remove the gears from the part tree. Do not twist them off without trimming the part carefully, because you may accidentally leave a small piece of the tree on the gear, which will cause the front diff to click when turned. This will make the diff bind and could cause damage to the diff, requiring new gear parts. See the picture below for a close look at what should be trimmed off.
This is what the larger gears should look like after they are installed. To achieve this, put them in from the same side and push them in at the same time. The brass gears will rotate and move the plastic gears into place. If the plastic gears are not installed correctly, the outdrives in step 13 will not be able to be installed properly.
Shown below is how the large gears should NOT look.
Install the silver washers. For extra lubrication, you should lightly grease the washers before sliding them into place.
Add some grease to the gears to lubricate the diff.
Install the diff covers to enclose the gears. These covers will snap into place. There will be a slight gap between the covers and the main gear diff enclosure, but with the aluminum tube in place the gap is not a concern.
Finally, slide the purple aluminum tube over the diff assembly to finish the job.
This is the completed front differential case.
