Of Lockers, Gears and Diffs
We need lockers and gears, and we not only need them, but we also expect them in any decently built four-wheeler. Certainly our Project Xterra, fit with extra horsepower and appropriate wheels and tires, was turning into a reliable, quality trail rig, but as we slipped over rocks and struggled up gnarly inclines, what we intrinsically knew became blindingly clear: It needed lockers and crawler gears.
Also, while we were whipping lockers into the differentials, this would be the perfect opportunity to swap out the X's stock 4.36 gears for a set of 4.88 gears from Nissan Motorsports. The ratio is a bit low, really, for our 31-inch Baja Claws, and makes the Xterra a bit buzzy on the highway. But it improved the X's crawl ratio to 35.3 from the stock 31.5. Add to that a significant reduction to the Xterra's low-range ratio and what we now have is a crawl ratio of 68.5:1.
To enhance the X's streetability, the lockers had to be selectable. We called ARB, knowing the company made a rear locker for the Nissan. Serendipitously, it turned out the company was developing a front locker for the Xterra. We got our hands on a prototype and headed over to the pros at Tri-County Gear, in nearby Pomona, California, to install the new lockers and gears.
Setting up new gears is truly a science in and of itself, requiring special tools and plenty of know-how. Unless you're schooled in the task, don't try setting up a diff on your own. As one of the Tri-County pros told us, "Proper setup can make the difference between your differentials lasting 3,000 miles or 100,000 miles."
Once we got the gears and lockers set up, we turned our attention to the Xterra's transfer case. Nissan specialist CalMini recently introduced a 3.92:1 low-range gear reduction for Nissan transfer cases.
We got a set, had the techs at Four X Doctor drop them in and hit the rocks. Here's a chronicle of our time at the shops. Special thanks to everyone at Tri-County Gear in Pomona, Off Road Unlimited in Burbank (ARB air compressor) and the Four X Doctor, also in Burbank (T-case gears).