BRP Johnson 4HP Service Manual page 151

Checking Reverse Gear
Check the reverse gear / pinion gear shimming as shown
below.
1. Feeling with your hand, recheck the condition by rotating
the driveshaft of the optimum forward gear tooth contact.
(See the page 8-18 and 8-19)
2. Install the following parts to the propeller shaft.
•
Reverse gear thrust washer
•
Reverse gear
•
Reverse gear backup shim
3. Install the propeller shaft and housing assembly to the
gearcase with the two bolts.
4. Rotate the driveshaft clockwise, then, using your hand,
compare the feeling with the feeling in the step 1.
•
If you feel that the rotating load is almost same as the
load in step 1, the reverse gear / pinion gear shimming
is right.
•
If you feel that the load is larger, reduce the reverse
gear backup shim thickness.
Checking Propeller Shaft Thrust Play
After adjusting all gear positions, measure the propeller shaft
thrust play.
Propeller shaft thrust play:
0.20 – 0.40 mm (0.008 – 0.016 in)
NOTE:
Maintain the forward gear thrust washer at the standard
thickness (1.0 mm) and adjust only the reverse gear thrust
washer with the shim.
Measurement step:
1. Assemble the gear adjusting gauge to the propeller shaft
as shown in the figure.

Gear adjusting gauge
2. Push the propeller shaft inward.
3. Hold the propeller shaft in and set the dial gauge pointer
to zero.
4. Slowly pull the propeller shaft outward and read the max-
imum thrust play on the dial.
•
If the measurement is more than the specification,
increase the reverse gear thrust washer thickness.
•
If the measurement is less than the specification,
reduce the reverse gear thrust washer thickness.
GEARS - SHIMMING AND ADJUSTMENT
GEARCASE
8-21