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4WD Hub Swap

Upgrade your axle hubs using OE parts

A few of the great reasons to own a 4x4 truck, SUV or Jeep-type vehicle are practicality, a sense of self-sufficiency and the confidence to explore remote roads or venture outdoors in inclement weather.

Regardless of make or model, most 4WD vehicles have the same basic way of "locking in" the front wheels. Power from the transmission is split between the front and rear axles by the transfer case, then that torque is multiplied by the gearing in the axles' differentials. In an "engaged" front axle, the power reaches the drive wheels by steel shafts turning inside the spindles. The very last mechanical connection takes place inside what's called the "locking hub." Automakers intentionally design most hub assemblies to be selectively "locked" whenever four-wheel drive is needed and "unlocked" at all other (good-traction) times for optimum fuel mileage, tire wear and longevity of 4WD system/front axle components.

Locking hubs typically come in two varieties: automatic and manual. Auto hubs are activated from inside the cab, either mechanically with a shift lever or electronically with a switch or button. Manual hubs require getting out of the vehicle and turning a dial on the hub face by hand to the Lock position. Though convenient, automatic hubs are generally weaker and more problematic than their less-complicated manual-locking siblings because they also rely on non-mechanical facets such as electrical connections and vacuum lines. Also, certain vehicles enable you to select a 2WD-Lo mode by unlocking the manual hubs and shifting the transfer case into 4WD low-range. This allows slow-speed crawling with the benefits of rear-drive-only steering for rare scenarios such as pulling a boat trailer up a ramp or backing up a steep driveway, ones where traction is less of a priority than the ability to crawl slowly without having to ride the brakes.

Hub Removal

In the early years of automatic-locking hubs (circa the early- to mid-eighties), auto hubs were often optional equipment. Since then, certain manufacturers have continued to offer both manual and auto hubs while others have either entirely scrapped manual hubs or have buried them deep down on the options list. (Most newer 4x4s rarely leave the pavement, and the average new-vehicle customer prefers the convenience of an in-cab-activated 4WD system.) The bottom line is that auto hubs can often be swapped for original-equipment manual hubs that were actually available from the factory for the vehicle.

The trickiest part is that not all automatic-hub assemblies couple the wheel hub to the spindle in the same manner (particularly on imports), so you need to be sure you have all the parts necessary to replicate the factory manual-hub arrangement. A factory service manual or "exploded" parts detail from your dealer will help determine what you'll need. (Aftermarket hub kits normally come with all the necessary parts, but many 4x4 owners are more comfortable using only "genuine" factory components.) Note how the automatic hub on the left uses one thick retaining nut with a locking ring while the manual hub requires two thinner nuts and two lock washers.

Once all of the parts are in hand, begin the job by safely supporting the weight of the vehicle on jackstands and removing the front wheels. Next, remove the hub cover plate (some domestic hubs don't have these) so that you can access the nuts holding the locking hub to the wheel hub. Remove all nuts and washers (some imports have both lock washers and cone washers) and remove the locking hub assembly from the wheel hub. If necessary for your vehicle, remove the lock nut and any other components that retain the wheel hub to the spindle.

Attachment Replacement

Paying strict attention to the manufacturer's specifications, begin installing the spindle nuts, washers and lock washers exactly as if you had performed wheel-bearing maintenance on a manual-hub-equipped vehicle. (In fact, a hub swap is an opportune time to also inspect and repack or replace the bearings.) Ensure proper wheel-bearing pre-load and lock-washer staking procedures. Next, turn the manual hub dial to Free or Unlock and slide the locking hub onto the wheel hub studs. Jiggle the hub to align it with the axleshaft splines and look for locating dowels that may require the hub to be installed in a certain position. Replace cone washers (if used), lock washers and nuts, and torque according to factory recommendations. Install the cover plate if equipped.

Finally, test for proper operation. With the engine off and the parking brake engaged, turn the hub's dial to Lock, shift the transmission into gear and the transfer case into 4WD. Try to spin the hub/brake assembly. If the hub is properly engaged, the assembly either won't turn or will cause the other front-wheel hub/brake assembly to turn in the opposite direction. Turn the dial to Free or Unlocked and ensure that the wheel hub spins freely and has completely disengaged from the rest of the drivetrain. Repeat the swapping procedure on the other side and you're done. You should now have a stronger and more reliable 4WD system.