Jeep Cherokee Upgrades: Manual Hub Conversion, Axle Replacement

Sep. 01, 2016 By Jim Brightly, KF7SCT

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Jeep Manual Hub Conversion and Axle Upgrade

Install the hub/rotor assembly onto the spindle (take care not to damage the rear seal). After installing the outer bearing, install the inner bearing locking nut.

The inner locking nut has a small pin that must be on the outer surface face, toward the wheel.

Use the proper spindle nut socket and torque the inner locking nut to 50-ft.-lb. After torqueing the nut, rotate the rotor in both directions to assist in seating the bearings, then loosen the nut a quarter-turn to release some pressure on the bearings.

Align the notch on the inside of the lock washer with the notch cutout in the spindle. Make sure the small pin mentioned in photo 18 is aligned properly for this lock washer.

Once the locknuts on both sides have been properly torqued down, check for end play. If any end play occurs, the preceding procedures will have to be repeated.

After installing the rotor/hub assembly onto the axle shaft—so that you won’t be getting grease and/or dirt on it any longer—thoroughly clean both sides of the rotor (where the brake pads rub it) with brake cleaner.

Install the brake pads in the calipers and then install the calipers. Slip the hub lock onto the spindle, then install the wheels, they hold the hub lock in place. Torque the lug nuts to Jeep’s specifications.

Move the dial on the hub lock into the lock position. As you spin the wheel, make sure the axle shaft rotates with the rotor (check both sides).

We had two additional steps that many of you won’t find necessary: Changing the differential cover and the fluid (so we had to clean out the gear case as much as possible). We’ll be using Royal Purple Max-Gear (75W-140W) synthetic gear oil, which is an ultra-tough, high-performance, GL-4 and GL-5 automotive gear oil designed to provide maximum protection to heavily loaded gears. It outperforms many other oils while maximizing power throughout the drivetrain because it combines high-quality synthetic oils with Royal Purple’s proprietary Synslide additive technology. Max-Gear makes your gears run smoother, quieter, cooler, and longer without overhauls. We think it’s worth the extra coin to get quality gear oil.

These Rugged Ridge Boulder high-strength cast-aluminum differential covers come complete with a magnetic drain plug for protection against costly damage from metal particles that can accumulate in gear oil. They also include a specially designed dipstick bolt to help Jeep owners avoid under or overfilling their differentials.

After completely cleaning and scraping the differential’s surface, apply RTV silicone to act as a gasket. Be sure to circle the bolt holes as well.

Finger-tighten all of the supplied flange bolts before tightening them. Torque all the bolts to 30-ft.-lb. in an alternating crisscross pattern.

Not liking the OEM cover (which doesn’t have a drain hole)—it uses a mounting bolt that’s also magnetic as a double agent—Barnes felt a new differential cover would improve the Jeep’s maintenance routine. The Rugged Ridge Boulder high-strength cast-aluminum differential cover (P/N RGG-1659513, $77) is constructed from A356-T6 aluminum for strong impact resistance and features a precision-machined sealing surface, allowing gaskets or RTV sealant to be used for a leak-free seal (we used RTV). The cover is designed to help protect the internal components from damage caused by contact with rocks and other off-road obstacles as well as aid in quickly dissipating heat from the differential.

Using Royal Purple Max-Gear (75W-140W) synthetic gear oil, fill the differential until the fluid begins to seep out of the filler hole, then insert and tighten the dipstick bolt. Use Loctite on the dipstick bolt and the magnetic drain plug to keep them from backing out accidently.

Just before loading the Cherokee on the lift for the install, we drove an 80-mile loop eastward out of Kingman, Arizona, on Interstate 40 for a mileage test. The route predominately climbs above Kingman’s 3,500-foot elevation but also covers rolling hills and fairly long flat stretches for 40 miles and then returns to Kingman in a reverse direction. Other than having no traffic (which introduces a variable because it can’t be duplicated), it’s an excellent repeatable route for mileage tests. The pre-conversion mileage was 15.1 mpg; while the post-conversion mileage was 15.38 mpg. Admittedly, this was a controlled test, so your results will vary, but it’s still a good indication of what your results will be. The other thing Mike noticed was that the Cherokee seems to drive and steer easier. In fact, it seems to accelerate better around town so in-town mileage may actually improve percentage-wise better than highway mileage.

Back on the trail again, but with a stronger, more reliable Dana 30 front end.