Yeah, you definitely need to have a bushing in there. You may be able to find something at the hardware store or make something. I was planning on trying the head of a rivet ( http://www.aeroassemblies.com/images/pop/rivets.jpg ) but haven't gotten around to it yet. If that doesn't work out, I'd just order a new pair of C-hubs AFTER doublechecking with Redcat that they have the updated bushings.

If all else fails, you could try using loctite and not tightening them all the way down. Obviously not the best choice.