gearing?
 

what size gears should i run in an e-maxx thats gonna have a lehner xl3100 w/warrrior 9918? also kind of pinion should i use?

I would start low and work your way up. If you're running a 66t spur gear , personally, I would start no higher than a 16t pinion. It does depend on the amount of cells you use and the weight of your truck, and I'm sure someone else on here would be able to give you a more accurate figure....All I will say is start low and work up.

The optimal gearing will depend on a few things, such as your terrain, tires, diffs, cell count, etc. For racing on a track, I would stick with a 14 or 15 pinion(assuming stock diffs and stock size tires). This also assumes 12 cells. For speed runs, you could certainly gear it higher, but for general playing around in varied terrain, stick with the lower gearing for better runtimes and cooler running.