Yamaha Outboard Motors Factory Service Manual F6 and F8, Page 358Get this manual
BACKLASH (6)Determine the shims to be added or removed according to the specifiedForward gear backlash Less than 0.88 mm (0.0346 in) Shim thickness To be decreased by (1.07Measurement) 2.52 To be increased by
More than 1.26 mm (0.0496 in)
(Measurement1.07) 2.52 Available shim thickness: 0.10, 0.12, 0.15, 0.18, 0.30 mm