Yamaha - Gear Idler 1 Lower Unit Gear Component 6CB-15512-00-00. Overview. When shifting starts to feel off, this is one of the parts I check early. The idler gear doesn't get much attention, but it plays a big role in how smoothly everything engages inside the lower unit. Once it wears, you'll hear it-grinding, hesitation, or just not locking in clean. Keeping a solid idler gear in place makes a noticeable difference in how the motor shifts and holds under load.. Key Features. • Smooth Gear Transfer - Helps maintain clean and consistent gear engagement during shifting.. • Precision Cut Teeth - Ensures proper mesh with surrounding gears to reduce wear.. • OEM Fit Accuracy - Matches Yamaha factory specs for alignment and dependable operation.. • High Strength Build - Designed to handle torque and repeated load in marine conditions.. Engine & Boat Compatibility. Verify compatibility with your specific Yamaha outboard model and part number before installation.. FAQs. Q1: What are signs th