I found that I had to force the large threaded rod axles in very gingerly. I didn't want to wreck the wooden frame. I also realized I should cover the wooden frame in fiberglass when I was done. I made sure that the distance between the 2 rear axles was short, because I didn't want to add 'guide teeth' or something similar to the plastic track and I had decided to do a triangular drive system to conserve space. This meant that any flex in the track was constrained by the sprockets.