1987-1993 Mercury Mariner Outboards 70/75/80/90/100/115HP 3 and 4-cylinder Factory Service Manual, Page 196Get this manual
6Assembly Pinion Gear Locating Tool (91-12349A2) as shown; do not tighten collar retaining bolt at this time 10Install the number "3" locating disc against bearing carrier shoulder in gear housing11Position access hole as showna -
Arbor Gauging Block; Install With Numbers Away From Split Collar Bolt; Gauging Block Retaining Split Collar Bolt; Collar Retaining Snap Ring
24643Locating DiscAccess Hole
7Insert tool into forward gear assembly; position gauging block under pinion gear as shown
12Determine pinion gear depth by inserting feeler gauge thru access hole in locating disc13The correct clearance between gauging block and pinion gear is 0.025I (0.64mm)14If clearance is correct, leave Bearing Preload Tool on drive shaft and proceed to "Determining Forward Gear Backlash," following15If clearance is incorrect, add (or subtract) shims from above bearing race to lower (or raise) pinion gearWhen reinstalling pinion nut, apply Loctite 271 on threads of nut22067Gauging Block