Dan, are these new gears? If so set them up as tight on the backlash as the manufacturer suggests, they will wear in some and the backlash will increase some on the first hard hit I like to shoot for the least amount of backlash as I can get away with(manufacturer suggested minimum) and get the pinion depth as deep as possible that still looks good Richmond recommends setting the pinion depth .010 deeper on a drag race gear set up than the depth printed on the back of there pinion gears.