As far as I know, Polyurethane is not on the approved list, so from our view, no, they are not polyurethane
We did try electrical tape and many varieties of heatshrink tubing, but none gripped well enough for our purposes.
The only thing I will comment on the gearbox is that it is so incredibly inefficient that you are losing more than 60% of your potential tractive energy inside this box. This is one of the main reasons that we are seeing so many smoked gearboxes. We have destroyed 3 of them ourselves. They need to be dramatically improved
