the Rotax "C" Gear Box - Gear Drive
1. Clean and degrease the
crankshaft end and mounting holes on the crankcase before
2. Using the Rotax fixation
tool (876 640) supplied in the Rotax tool kit lock the engine up
by installing the pin into the impulse hole, used to run the
fuel pump. With the pin in place rotate the engine, until it
3. Install flywheel onto
crankshaft end. Install flat washer onto bolt install bolt..
Torque to 45 FOOT lbs.
4. Install allen screws
with washers into hardee disc. Install Hardee disk onto
crankshaft as shown. Use loctite 242 on bolt threads. Toque to
30 FOOT lbs. While torqueing use a 17 mm wrench to prevent
special flat sided washers from turning.
5. If Hardee disc is banded
6. Install back half of
gear box housing onto engine with the 8 bolts provided. Apply
loctite 242 to bolt threads before installing. Torque to 195
7. Install #16 shims onto
the pinion shaft.
8. Install anti-seize
compound onto pinion shaft, and install #4 coupling flange.
Torque allen bolt located in the center of the flange to 195
9. Install gasket (#21) -
install front gear box housing and prop shaft onto rear housing.
Torque all 6 mm fasteners in an X pattern to 95 INCH lbs.
10. Remove fixation tool
from impulse hole.
11. Fill gear box with 90
weight oil until oil runs out the lower of the two side plugs
(about 4 ounces).
12. Tighten then safety
wire top and bottom plugs.
13. Tighten then safety
wire vent cap and drain plug.
For the Rotax "C" drive gear box, lubrication oil level is
very critical. When servicing, fill slowly to the lower of
the two screw holes on the side of the case (#39), and then
replace the screw and washer, and safety wire the two oil
On new gear boxes, change oil after the first 10 hours of
operation and then every 100 hours after that.
Rotax redrive gears must always be replaced together, this
is because of the gears have worn together as a unit and
replacing one would only result in premature wearing of the
The two large holes on the side of the Rotax "C" drive gear
box, (where you can look in and see the rubber coupler) are
for cooling of the rubber shock mount, inside the drive
system and must be left open.
If there is evidence of gear oil on the bottom of the gear
box where it meets the crankcase, or in the two holes
referred to above this could indicate a failed seal (#13)
inside the gear box.