Agree, when the main or rod cap is toqued the pressure of the mating ends of the bearing in the cap press on the ends of the bearing in the rod or main bridge and lock each other in place. Any excess oil or lube on the back side of the shell would simply escape out the sides. Some folks think the bearing lock notches hold the bearing in place to prevent it from spinning. No so, the notches are there to properly orient a bearing to an oil hole. It’s the pressure on the mating ends of the bearing shells that hold the bearing in place.
