3103-12 – Transmission Yokes – 1310 Series – 10 x 1.375 Splines – 2.125″ Hub Dia

3103-12 -- 1310 Marine Jet Drive Transmission Yoke

The 3103-12 is designed for standard marine jet-drive installations where the engine output shaft uses a 10-spline, 1.375" pitch diameter interface. The oversized 2.125" hub diameter is a distinguishing feature of jet-drive yokes -- the larger diameter accommodates the heavy-wall housing bore of the jet pump input coupling. The 0.875" counterbore seats on the pump coupling pilot to maintain alignment, which is critical in a marine environment where vibration from water ingestion can otherwise accelerate coupling wear.

At 4.875" center-to-end, this transmission yoke is sized for standard jet pump geometry. The 10-spline count is much lower than automotive applications -- these splines carry torque rather than provide fine-pitch indexing, so they rely on a tight interference fit rather than close-clearance slip engagement. Apply anti-seize compound to the splines during installation to prevent corrosion bonding in the marine environment. The 1310-series U-joint at the output end (1.062" cap) should be replaced annually or every 100 hours in saltwater applications, whichever comes first.