[Joe G.]

We did a belt drive this year for our six wheel drive. We set it up with the wheels cantilevered, and the belts captured between two sheet metal C channels. Worked out well. We used 36 tooth 5mm HTD pulleys and 15mm wide belts, which was probably overkill. Could have definitely gone with smaller pulleys if we'd used GT2, but our drive ended up sized perfectly to use one of the FIRST choice HTD belts that was avaliable, so we went with that. Always use the documentation on belt loading from Gates to size your pulleys.

We used timing belt pulley stock from SDP/SI and custom turned our sprockets, which was a great move. Saved us about $100, and allowed us to custom size and broach the pulleys to fit our needs. The center wheel was a double pulley, which was simply an extended length of the pulley stock. We used pieces of laser cut delrin screwed onto the faces of the pulleys to build custom flanges.

Center center distances were calculated using the SDP/SI's calculator. We didn't add anything, though we've heard of teams adding a few thousandths to this number. Worked great, belts were tight, and we never threw or broke one all season.

One key thing to remember when switching to belts from chain is that you cannot open up a belt like you can a piece of chain. Therefore, you have to think through any and all structural members that run through the belt's loop, and make sure they can be installed after the belts are in place. Also, if you go with an exact center-center design rather than a tensioner, make sure you think through how you will pull the belt tight for installation. In our design, we installed the corner wheels first, and allowed the center pulley to float with its axle absent. The tension on each side of this pulley cancelled out, allowing us to then slip the center axle in and lock everything together.