Honda BF35A-BF45A Outboard Motors Shop Manual., Page 405Get this manual
10) Hold the bottom piece in vise with shop towel or soft jaws as shown and loosen the outer tube using the lock nut wrench, then remove the cylinderpiston assembly from the vise[I] LOCK NUT WRENCH 30 40 07916-9690000
CAUTION: Take care not to tighten the vise too tight as it damages the bottom piece
BOTTOM PIECE
11) Remove the outer tube by loosening the outer tube slowly, and drain the residual ATF from the outer tube and cylinderRemove the O-ring from the outer tube using small screw driver taking care not damage the O-ring installation section, and discard the O-ringReplace the 0ring with new one during reassemblyClean the threads of the outer tube