[Oblarg]

Originally Posted by Chris is me

There are a lot of ways you could be putting a bending moment on the coupler so how the shaft is supported is critical.

The output shaft of the gearbox is contained inside a piece of aluminum tubing (the chassis member to which the gearbox is attached). In the side of the tubing opposite the gearbox, coaxial to the output shaft, there is a hex bearing. The wheel shaft runs from that bearing through a bearing in a piece of aluminum sheet on the other side of the wheel.

Edit: Here's a picture of the CAD I'm currently toying around with; the plate on the far side of the wheel hasn't been designed yet, and thus is absent, but this should give you an idea of the setup. The coupler is currently inside a piece of 2''x1.5'' tube; I'm wondering if I can get away with 2''x1''.