Are you using threaded rod as an axle for the traction wheel?
I ask because we've tried doing that before, and it didn't work very well, the axles bent after only a few minutes of driving. Then again, I think we were using pretty small rod, I think it was 3/8", but it might have been 1/2", I can't remember exactly.
Also, what is keeping your wheels centered on the axles?
The module is looking pretty excellent though! Can't wait to see the finished product!
