How about chain drive from the original axle flange to a split jackshaft to mount your oversize rear tires? This should move drive strain from original drive line to parts heavy enough to handle the workload -and be easily adjustable ratio if you later want to change it.
Basically like a chain drive MACK truck.
I'd probably try 4 or 5 to one to start; our 12hp singles do not have as much torque as the 60ci. four cylinders in full size CUBS. A simple flange with a stub shaft to bolt on the wheel flange should get you started.
wayne
|