Mercury - Gimbal Bearing Alpha One Gen II & Bravo Series Precision Steel Construction 879194A01. Overview. There is a certain confidence that comes from a sterndrive that feels tight, clean, and responsive every time you throttle up. When your gimbal bearing is healthy, the whole boat seems to move as one-steady through chop, smooth in the turns, and quiet when shifting into gear. But when that bearing begins to wear, you feel it long before you see it: a faint vibration, a hum that should not b