Yamaha 25BMH 30HMH Factory Service Manual, Page 314Get this manual
SHIMMING
E (4) Calculate the pinion gear shim thickness (T3)Pinion gear shim thickness (T3)- 27 mmP100 mm NOTE: "P" is the deviation of the lower case dimension from standardIt is stamped on the trim tab mounting surface of the lower case in 0.01 mm unitsIf the "P" mark is missing or unreadable, assume "P" value of "0", and check the backlash when the unit is assembled If the "P" mark is negative (-), then add the "P" value to the measurementExample: If is "28.30 mm" and "P" is "+5", then: T328.30 mm27 mm(+5)100 mm1.3 mm0.05 mm1.25 mm (0.049 in) If is "28.24 mm" and "P" is "-3", then: T328.24 mm27 mm(-3)100 mm1.24 mm0.03 mm1.27 mm (0.05 in)