[sdcantrell56]

I am talking about not having the transmission output shaft directly driving a wheel. Maybe put the transmission between a pair of wheels and chain them to the transmission and then chain the middle one to the last unchained wheel. As you have it right now there is a large cantilevered load on the output shaft which I would be wary of.

I am also wary of a bearing bore in wood like you and the few wood designs I have worked on have all used aluminum bearing blocks to hold the bearings.