Allpar learned this week that a new 2.72:1 Selec-Trac full-time four wheel drive system will be available on Sport and Sahara models of the JL Wrangler.  This sparked immense discussion, including the difference between part-time and full-time four wheel drive.

In a part-time system, the only choice on current Wranglers, drivers choose whether to have all four wheels, or just the rear wheels, powered at any given time. The problem is that, if the surface is not slippery, the tires “scrub,” and the turning radius is much larger than with just rear drive. In a full-time system, clutches balance out the rates of speed for the wheels, and drivers can go on any surface with the system active. Today, the systems are usually set up to come into play when needed, with computers calling the shots (and rarely-used manual overrides).

Since the JL has not yet been unveiled, Allpar has done some digging to try to speculate what the system may actually be.  Based on the noted low speed gear ratio of 2.72:1, the system may use the MP2023 transfer case (also used in the Jeep Grand Cherokee’s Quadra-Trac II setup). That is connected to the same V6 engine and eight-speed transmission, and has the 2.72:1 ratio.


The MP2023 transfer case would provide:
  • Active, on-demand four-wheel drive that requires no input from the driver — instant detection of wheel-slip and preemptively redirecting torque as needed.
  • Stability under all conditions, because torque is constantly being transferred.
  • Two speed gearbox, with 4WD Low operation mode.
  • Electric shifting between 4WD Auto and 4WD Low for smooth operation and lower noise and vibration than mechanical linkages.
  • Enhanced traction and stability as the stability and traction controls work in tandem with the AWD system.
  • A neutral mode that permits flat towing (e.g. behind a motor home).

The Quadra-Trac II system in the Grand Cherokee uses an electronic dial, dubbed “Selec-Terrain,” to switch between modes; it, too, has an automatic mode. A similar dial could be installed in place of the JL’s center-console transfer case lever.

selec-trac modes

A system like this could be a game changer for the JL Wrangler.  Being fully automatic would make the JL safer to operate, providing seamless, easy operation with low NVH, appealing to novice Jeepers and daily drivers.  It would also appeal directly to former and current XJ Cherokee owners who prefer an automatic four wheel drive system... especially if a closed-roof variant is made to head off the Bronco, or if the Wrangler hard-top option is executed well enough to take its place.

Allpar has not confirmed this story, but there is certainly excitement about the potential of this system; given how many Wrangler buyers live in urban areas or use their vehicles for adverse weather rather than pure off-roading, it should have a high take rate and perhaps garner new buyers (or repeat buyers).

Sources:  Allpar, JLWranglerForums, WK2Jeeps