Yamaha Outboard F15A F9.9C, FT9.9D F15 Service Manual, Page 318Get this manual
SHIMMING (EXCEPT FOR USA AND CANADA) (F15AF9.9C)
Example: If the measurement is 1.02 mm, decrease the shim thickness by 0.18 mm (i.e 1.201.020.18)If the measurement is 1.32 mm, increase the shim thickness by 0.12 mm (i.e 1.321.200.12)Available shim thickness: 1.13 and 1.20 mm
Find the forward and reverse gear's shim thickness by measuring the backlash
SHIM SELECTION (EXCEPT FOR USA AND CANADA)