Easiest way is use a pair of channel locks, if you don't have a torque wrench and socket. Hope this makes sense. Tighten nut while spinng the wheel ( reason for this is to insure the seal gets seated properly ) tighten pretty snug but don't have to over do it. Then back off one flat. That is one of the flat sides on the nut that a wrench or socket would fit on. Pick a flat and back up until the next one is in the same position. Try to insert cotter pin, if necessary back nut up just until the cotter pin goes in and through the axle. Never leave a bearing nut tight. Tapper roller bearings should have somewhere from 8 to 12 thousands end play. If this makes no sense ask away.
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Charlie Weaver USN/ENC 1965-1979