Rebuilding the Differential
The gears in the differential will wear over time. The same is true for the outdrives, driveshafts and
rear axles. We suggest using a small rag or paper towel to lay out the parts you remove to make it
easier to reassemble.
1) Unplug the motor. 2) Remove the gear cover (three screws). 3) Remove the motor guard screws at
the top of the transmission and the two lower extreme rear bottom of the chassis. 4) Remove the screw
that attaches the rear shock tower to the transmission and the 4 long flat-head screws at the bottom of
the chassis that hold the gearbox in place and slide it out of the chassis. 5) Remove the left side of the
gearbox by removing the three screws. 6) Follow Figure 1 below to rebuild the differential (use LOSA3066
Grease). 7) Once the differential has been rebuilt, assemble the transmission by following the steps in the
reverse order. Be sure to use the screws in the same location that they were removed from.
Changing the Spur Gear
Remove the gear cover by removing the three small screws. Remove the slipper adjustment nut at the
end of the slipper shaft and all of the slipper parts on the outside of the spur gear as well as the old gear.
Place the new spur gear into position and replace the slipper parts. After you have changed the spur gear,
you will have to adjust the slipper as described in the “Slipper Adjustment” section on page 3.
Changing the Pinion Gear/Gear Ratio
Before you change the pinion, ask yourself why you are doing it. In general, if you change to a larger
pinion the top speed will improve, but you will see less acceleration and run time. This would only be
advisable for really long track layouts with few tight turns. Changing to a smaller pinion will give you
quicker acceleration and possibly a bit longer run time but a little less top speed. This would be good for
short layouts or when running faster motors. The Micro Raminator comes with a 10T pinion that offers
the best balance of both. To change the pinion, remove the gear cover, loosen the motor screws, and slide
the motor back. Use a small flat head screwdriver between the motor plate and pinion gear to push the
gear off. Place the new pinion on the end of the motor shaft and press the new pinion gear into the same
position as the one removed.
Setting the Gear Mesh
The motor screws should be slightly loose. Slide the motor forward allowing the pinion
gear to mesh with the spur gear. Snug (not tight) the bottom motor screw and try
rocking the spur back and forth. There shoud be a slight bit of movement before the
motor is forced to turn over. If not, pull the top of the motor back slightly and recheck.
If there is too much slop between the gears, push the top of the motor forward. When
set properly, the wheels can be spun forward freely with very little noise. Make sure to
tighten both motor screws and replace the gear cover before running.
Page 5
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Figure 1.
