Yamaha Outboard F15A F9.9C, FT9.9D F15 Service Manual, Page 320Get this manual
SHIMMING (EXCEPT FOR USA AND CANADA) (F15AF9.9C)
Forward gear shim
Find the forward gear shim thickness (T1) by selecting shims until the specified measurement (Mv1) is obtained with the special tool
1Measure: Measurement (Mv1) Shimming plate: 90890-06701 Digital caliper: 90890-06704