Mercury 35/40HP 2 Cylinder Outboards Service Manual PN 90-42794--1, Page 149Get this manual
4Push bearing carrier into gear housing while rotating drive shaft to engage pinion gear teeth with reverse gear teeth5Install alignment key (a) IMPORTANT: For proper retention between housing and cover nut, it is recommended that PLASTIC cover nut (if equipped) NOT be reusedReplace as required6Apply Quicksilver Special Lubricant 101 onto threaded area of gear housing (b)
Checking Forward Gear Backlash
NOTE: Read entire procedure before attempting any change in shim thickness1Obtain correct pinion gear depth Refer toChecking Pinion Gear Depth" preceding 2Install components as shown