2007-2009 Yamaha F15/F20 Outboard Service Manual, Page 177Get this manual
Shimming 2Calculate the forward gear shim thicknessCalculation formula: Forward gear shim thickness (T1)0.13Select the forward gear shim(s) (T1) as followsCalculated number at 1100th place 1, 3, 4, 6, 7, 9, 10 Rounded number 8 S6AG6480
Available shim thicknesses: 0.10, 0.12, 0.15, 0.18, 0.30, 0.40, and 0.50 mm Example: If "T1" is 0.23 mm, then the forward gear shim is 0.22 mmIf "T1" is 0.30 mm, then the forward gear shim is 0.28 mm10 mm (0.39 in)