Yamaha - Gear 1 (26T) Lower Unit Gear 6DB-45560-00-00. Overview. When you're dialing in a Yamaha lower unit, the first gear in the set plays a big role in how everything feels once you're on the water. This 26-tooth gear is built to engage clean and carry load without hesitation, especially when you're shifting into gear or pushing through rough conditions. I've seen plenty of worn gears cause vibration and noise that throws everything off. Put in a solid gear like this, and the drivetrain settl