You've got some more fab work to do yet, eh
... like fill in the gap between the idlers to spread the weight over the entire track for better traction.
http://www.rctruckandconstruction.co...hp?t=71&page=3
RCLogger used strip of hard plastic, maybe puck board, along the bottom length between idlers & just simulated rollers by cutting out the C channel. This dozer is 6yrs old & as far as I know he's never changed the plastic strips... but of course this is a smaller lighter dozer than what you have built.
Are your tracks spring tensioned at all?
You might want to fab up some track guards too to keep the dirt/rocks out of your links.