Doing more with less is what four-wheeling is all about these days. Sure, we'd all like an earth-dominating rig that never breaks and has limitless power, but unless you're a sheik, it's probably not going to happen. We're like most of you when we look at building a rig. We need it to perform well, make it to the trail and back home, and then stay together long enough to endure our weekly commute.
Recently we tossed on a 4-inch lift and 33-inch Claws on a '97 Jeep Wrangler TJ that's equipped with an extremely tired 2.5L four-cylinder engine. Usually a tire that's only 33 inches tall won't rob all of your power, but for this creampuff the stock 4.10 gears were just not enough to maintain highway speeds. Trail performance definitely suffered too. We needed a power solution, and since an engine swap isn't in our budget, we opted to install a set of 4.88 gears to bring the underpowered wheeler back to life.
After receiving our new Superior gearset and master install kits from 4x4 Drivetrain Parts, we headed to the Jeep experts at Cape Fear 4x4, on the Carolina coast. Over the course of a few hours, during the changing out of the ring-and-pinion in our Dana 30 front and Dana 35 rear axle combo, we noted important things to watch for. Although it is not exactly reinventing the wheel, setting up gears does take skill. We suggest taking your rig to a pro if you are the least bit unsure. An improper gear install can translate to more problems and cost you way more than the few hundred bucks you tried to save by doing it yourself.
 1. An open differential means...  1. An open differential means that the carrier houses the factory spider gears that allow the tires to rotate at different speeds. If it were a locked differential, the tires would rotate at the same speed. When changing gear ratios, you must match up the gearset with the appropriate carrier. For our Dana axle combo this means keeping the factory 4.10 carrier since we are swapping to a numerically higher 4.88 gear ratio. If we were to swap to a lower numerical ratio, such as a 3.55, we would need a carrier that accommodates the lower ratio. |  2. Oftentimes carriers require...  2. Oftentimes carriers require that the shims be placed between the carrier and bearing. These internal shims will require setup bearings. Setup bearings are loose-fitting dummy bearings that prevent you from having to press your new bearings on and off the carrier, as it may take a few shots to determine the correct number of shims you need. Our Dana 35 rear axle uses external shims, which mount to the outside of the carrier bearing. |  3. Before removing the four...  3. Before removing the four carrier cap bolts that secure the carrier in place, be sure to mark or indent each cap so that you can reinstall it on the proper side. This keeps the alignment of the caps true to the housing so the bearing races are true in the bore. While the carrier is out is also a great time to inspect the housing for damage. |
 4. The pinion gear drives...  4. The pinion gear drives the ring gear. It's equipped with splines to accept a drive flange or yoke to connect to a driveshaft. Each ring-and-pinion is made in a set and will be labeled with matching numbers to indicate so. |  5. A hydraulic press and bearing...  5. A hydraulic press and bearing puller are two must-have tools for removing the old bearings and installing the new. Be sure to inspect your old carrier bearings closely, as oftentimes heat or lack of lubrication will cause the bearings to spin and damage the carrier. |  6. To determine the proper...  6. To determine the proper ring and pinion teeth contact, you'll need to examine the contact pattern. Brush both sides of the ring gear, then rotate the painted section of the gear until it meshes with the pinion. You'll be examining both the drive (flat) and coast (concave) sides to find out exactly where the two meet. Many install kits come with instructions on what is an acceptable pattern. Depending on the pattern, you may need to adjust the pinion depth in the housing with shims and the carrier position side to side. |
Dial In
Having a dial indicator is extremely important and will spare you from guessing if everything is set up correctly. Don't be surprised if it takes you a few times to land the suggested numbers and gear pattern, as installing gears isn't a cake walk for the average wrencher. Also, gears need to be broken in, so as bad as you will want to go right to the trail and test your new power, we suggest that you wait. Though it may be tough to do, for the first 100 miles or so, try and drive your vehicle in short bursts to allow the gears to cool off. And be sure to wait until you've tossed on around 500 miles before towing or drag racing your neighbor's hot rod.