2001 Edition Yamaha F225A and LF225A Outboards Service Manual, Page 188Get this manual
Lower unit
3Measure the clearance (M) between the shimming tool and the ball bearing as shown
Selecting the reverse gear shims
1Calculate the specified value (M0) as shown in the examples below
NOTE: "R" is the deviation of the lower case dimension from standardThe "R" mark is stamped on the trim tab mounting surface of the lower case in 0.01 mm unitsIf the "R" mark is unreadable, assume that "R" is zero and check the backlash when the unit is assembledCalculation formula: Specified value (M0)0.50 R100 mm Example: If "R" is (+5), then M00.50 (+5)100 mm0.50 0.05 mm0.45 mm If "R" is (3), then M00.50 (3)100 mm0.500.03 mm0.53 mm 2Set the shimming tool on the ball bearingShimming gauge 1: YB-06439