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How to Make Them Last: Gear Setup Tips from the Experts

What to know before attempting your own re-gear

Jerrod JonesPhotographerTed OlmstedPhotographerAgustin JimenezPhotographer, Writer

Adding bigger tires to a 4x4 is a rite of passage that we all go through in our early days of four-wheeling. Most of us of are of the mentality that you can never have too much of a good thing, like ice cream, bacon, and of course, big gnarly tires! The more rubber between your wheels and the trail, the more places your rig can conquer off the beaten path. While it sounds like a great idea, it's not without some consequences, the biggest of which will be having enough power to make your rig move out of its own way with the parasitic loss of larger tires. The quickest way to gain that lost power back is to upgrade the gears on your rig to a lower ratio (numerically higher) gear-set.

Your new gears should be chosen based on the size of the tires you'll be using, as well as the type of wheeling you'll be encountering and whether or not you will trailer your 4x4 to the trailhead or daily drive it on the highway. Once you have done your homework on what the proper gear ratio your 4x4 will need, you'll need to decide whether you want to try your hand at setting up your own gears or taking it to a knowledgeable installer to make sure the job is done right.

Installing gears isn't quite as easy as most people might think. It's the little details that can mean the difference between a long healthy gear life and a trip home from the trail on a tow truck. We've decided to show you some of the finer points of a proper gear installation for a stronger and longer-lived gear-set in a high-torque application that routinely sees gnarly off-road conditions, along with brutal daily driving duties in heavy traffic conditions.

Our 2003 Ford F-350 Super Duty is a long-term project truck from our old sister publication, 4-Wheel & Off-Road magazine. This 1-ton, 6.0L Power Stroke diesel truck has seen more than its fair share of abuse over the years, but after our last desert outing, old Big and Purple decided to develop a slight vibration in the rear end while flat towing a Baja Bug out to the desert. We knew something was definitely wrong when we pulled the magnetic dipstick on our rear Mag-Hytec differential cover and were greeted by a chunk of ring gear tooth. Of course we didn't let it spoil our weekend, so we pushed on the rest of the way and drove it back home in front wheel drive after pulling the rear axle shafts and driveshaft.

We decided that the funky combination of 5.13 gears meant for a Sterling 10.25 in our Sterling 10.5 might have been a little more than we needed for a truck with 40-inch tires and gobs of low-end torque, so we ordered up a brand-new set of Yukon Gear and Axle's 4.88 gears and master overhaul kits for both the front Dana 60 and the Sterling 10.5 rear in our high-mileage Super Duty.

When it comes to properly installing gears on our trucks, we always go to the experts. South Bay Truck and 4x4 has done countless gear installs for us in the past that are holding up strong to this day, so we couldn't think of anyone better than them to share with us the secrets to properly setting up gears that will last for a long time in a high-powered, highly abused 4x4. Check out all the preload, pinion depth, and backlash wisdom that they shared with us to make your next set of gears stay in it for the long haul.