4x4Wire JK Build: Gears, Lockers, and Lift

4x4Wire JK Beginning with the purchase of a 2010 JK Unlimited Sport just over two years ago, stage one of the 4x4Wire JK build is now complete.  Off the showroom floor, it did have a Dana 44 rear end; but, otherwise stock with air conditioning and a 3-piece hardtop.

The focus of this build will be to showcase products that increase off-road capability of the JK and stay within a budget.  While price is a consideration, quality is the primary focus.  Many of the upgrades considered do change the characteristics of the vehicle from the stock configuration.  All upgrades will focus on quality as that is a direct link to safety.

Since driving off the showroom floor, I have had the JK in the dirt enough to check handling and performance in four wheel drive.  I would like a little more in the engine.  The 3.8l is adequate but does lack a little in highway performance.  That does have one up-side: less throttle, less speed, fewer tickets...

My goal is to build a JK that maintains decent performance on-road as well as off-road. The initial phase is a basic lift, locker, and gear install.  Future modifications such as bumper replacement, full skid plate and rocker panel protection will come at a later date.  Those upgrades will be determined by strength and weight factors in addition to quality and safety.

As the stock tires were wearing and in need of replacement, the time came to consider Stage One of the build that would consist of lift, gearing, and lockers topped off with a new set of tires.  Finally, I could get the set of 295/75R16s out of the garage and put them to good use.

That set the basic lift criteria - accommodate 35” tires.  A review of available offerings came down to the Rubicon Express 3.5” Econo Lift. The lift was topped off with Bilstein shocks and the Rubicon Express Gen 2 Disconnects.  The RE disconnects have a quick-release pin and a mounting point just above the frame to fasten the sway bar up and out of harms way. 

Next came the gearing decision.  Original desire was for 5.13 gear ratio as an optimum match for tire size and lessening the engine RPM at highway speed.  However, there have been numerous reported durability problems with that gear ratio.  As durability was important, the gear ratio was scaled back to 4.88.

The important decision was lockers.  You cannot beat durability of the tried and true Detroit.  But, as it is a full time locker, it is not highway friendly and defiantly not ice road friendly.  My desire was to have more “locker” than provided by a limited slip, the choice was between ARB air-locker and electric locker.  I selected the Auburn ECTED electric locker.  With this locker, you do get a full-time limited slip which becomes a full-time locker with the flip of a switch.

Front DifferentialThe locker install does require some case modification.  Some grinding is required for fitment into the Dana 30 where slight grinding is required to attain required clearances. The locker also requires a hole be drilled to accommodate the electrical wiring.  While most common (and easiest) install uses a “press-fit” for the fitting the houses the wires, it is preferable to drill and tap a hole.  The threaded hole provides a more positive, long term fitting and is easier to seal.

The lift install did provide one complication - clearance for the rear sway bar.  That means the stock wheels (with 5.75” offset) cannot be used with the RE lift.  To ensure proper clearance with the rear sway bar linkage, a 4.5” or less offset is required.  Other lift types may have similar considerations.  Here it is best to check your state vehicle regulations.  Depending on the state, there may be limitations covering how much of the tire width can be exposed or not covered by fender or flares.

As I am partial to steel wheels, I selected the Pro-Comp 16x8 with the 5-5 bolt pattern and offset of 4.25” to hold the 295/75R16 BFG All-Terrains.  The tires were a left-over from a previous project where the decision point was to go with 35” tire and light weight.  The P-metric radial style of the 295/75 is about a .5 inches shorter than a 35” tire and almost 10 pounds lighter.  Overall, when considering a lift, careful attention to tire size and wheel dimensions is required. 

Front DriveshaftAnd, new drive shafts are required. Here, you do have a choice.  The stock drive shafts can be modified which will save some cost.  However, given the larger tires, there is a potential for early failure.  I opted to install new upgraded custom built driveshafts.

In most cases, that should complete a basic lift, locker, and gear install.  I did deviate from the norm by swapping transfer cases.  While the stock transfer case is a relatively strong unit and features a 2.72 low range gear ratio, I did have available an upgrade opportunity - a 4:1 transfer case as featured with the Rubicon Wrangler upgrade from the factory.

Finally, with the tire size and gearing changes, one final change is necessary -- re-programming the on-board computer.  That is accomplished with a simple tool that can change the engine control settings and adjust for tire size and gear difference.  There are several choices available.  I opted for the the AEV ProCal Module.  This allows modification of the computer to account for increase in tire size and change in axle gear ratio.

Basic specs of the 4x4Wire JK are 4.88 gearing, 4:1 transfer case, automatic transmission, with 35” tires.  The beauty of the JK compliments (or contrasts) the Beast that sees serious trail use - 94 YJ, 4.56 gearing, 4.3 Atlas Twin-stick, NV-4500 (6.34 low), spring-over with 35” tires.

The 4x4Wire Jeep stable now features Beauty and the Beast...


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