BRP Johnson 4HP - Forward Gear; Pinion Gear Shim Adjustment; Lower Unit Gears-Shimming and Adjustment

8-18
GEARCASE
GEARS - SHIMMING AND ADJUSTMENT
Forward Gear / Pinion Gear Shim Adjustment
Adjust the forward gear / pinion gear shimming as shown
below.
Step to prior to adjustment
1. Install the following parts to the gearcase.
• Forward gear bearing (if removed)
• Forward gear backup shim
• Forward gear
• Pinion gear thrust washer
• Pinion gear backup shim
• Pinion gear
• Driveshaft lower washer
• Driveshaft (with two circlips)
• Driveshaft support housing gasket
• Driveshaft support housing
2. Install the driveshaft support housing with the two nuts
diagonally.
NOTE:
Use a spacer (such as a M8 nut) in order to secure the hous-
ing onto the gearcase without the water pump case.
Adjusting gear backlash (Pinion and Forward gear)
To check the backlash, hold the driveshaft by hand, then
gently rock forward gear back and forth by hand.
Gear backlash: 0.10 - 0.20 mm (0.004 - 0.008 in)
• If backlash is larger than specified, the thickness of the for-
ward gear backup shim must be increased.
• If backlash is smaller, the thickness of the backup shim
must be decreased.