Issues with Vex clamp on gearbox and 4 inch wheel

Due to not having a lot of access to a machine shop we decided to purchase products from VexPro and used their 4" mecanum drive base example as our frame (same dimensions and same parts). After some driving and wearing the wheels down a little bit (not an extreme amount) we noticed that the gears were actually in contact with the floor as well.
We used the same dimensions that VexPro used and the exact same sized gears with the new 4" mecanum wheel.

I have sent an email to vex about the issue but have not heard back.

Are any other teams using the VexPro clamp on gearbox with a 4" mecanum wheel experiencing similar issues?

Here is an image of us trying to slide a piece of paper under the gear.

https://onedrive.live.com/redir?resid=CEBED2B660E90E05!13247&authkey=!AFrATliSoUxXp0Y&v=3&ithint=photo%2cjpg

If you use a gear that is almost as large as the wheel’s diameter, then of course you’re going to have very little ground clearance. Two factors to always consider: The wheel will always dip into the carpet a bit, and the field is never perfectly flat, so there will be some bumps and ridges. Try using a 13:70 gear spread. The 72T gear has an outer diameter of 3.7" (radius of 1.85"). The 4" wheel has a radius of 2". That means on a perfect surface with a perfect setup you should have 0.15" of ground clearance, which in competition condition is still very little. Combine that with about 3/32" of carpet deformation and about 1/8" of bumps and ridges on the field (those two numbers being very generous guesstimates), and you’ll find yourself with negative ground clearance (aka your gear touching the carpet).

Of course I understand all of the math behind what is going on, the 13:70 is one I was looking to switch to as well. And probably the easiest to do.

Like I said we had very little wear on our wheels just surprised to see Vex suggest a reduction that gives you maybe a day of driving then all of the wheels would need to be replaced. This is the first year I have used vex mecanum wheels and they so far are not holding up well.

I would like to hear about other teams that are using the same setup and see if they are experiencing similar troubles.

I don’t believe vex has 70 tooth (I thought they did) so probably the 64 tooth will have to work just need to find the correct gears that will still provide a good mesh in the clamping gearbox.

http://www.wcproducts.net/gears-w-versakeys

Not found under normal hex bore but with versakeys.

Awesome, going to probably order these later today.