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Clarifying: JL 4×4 vs 4WD

by David Zatz on

The recent revelation that the next-generation, 2018 Jeep Wrangler JL will have an optional full-time four wheel drive system struck a nerve with some, who saw it as being inappropriate for the vehicle.

The current Wrangler’s part-time system stays in rear wheel drive, unless the driver pulls a lever to activate the other wheels. Then, power is mechanically split, 50/50, front to rear; and, since the wheels usually don’t all travel at the exact same speed, and there’s no “give” in the powertrain, the tires slip against the surface, causing wear. It doesn’t matter much on snow, ice, sand, or gravel, but on pavement, it wears the tires quickly.

Part-time systems, when engaged, also dramatically increase the turning radius, which can cause crashes if it’s not expected.

While all Wranglers are capable of tackling very serious off-roading, few owners actually put them through their paces. Even when Jeep was a low-selling AMC niche brand, less than one in ten buyers took their new Jeeps on land that an AWD Charger couldn’t handle. CJs and Wranglers still dominate off-road meets, but that’s a fraction of the hundreds of thousands of SUVs sold each year.

selec-trac

Most buyers want a vehicle that can handle bad weather, not big rocks or streams. For them, full-time four wheel drive is a better choice: it doesn’t affect the turning radius or scrub the tires, and saves fuel by staying in RWD most of the time.  Having a full time 4WD option would tailor the Wrangler to the typical buyer, rather than to the image — staying true to Jeep’s “engineered to a purpose” past.

There is no way of knowing what kind of 4WD system will be used —  a resurrection of a prior Jeep system, which worked mechanically while allowing slip, or one similar to the Grand Cherokee’s, which relies on “traction tricks” using ABS and such.

Reliable Allpar source oh2o wrote that the Rubicon will continue with its sole and exclusive Rock-Trac heavy-duty part-time four wheel drive setup, with its 4.0:1 low gear ratio. However, buyers of the Jeep Wrangler JL Sport and Sahara will have a choice between the Command-Trac part-time system and a Selec-Trac full-time setup.  The part-time system will still be available on each model, for the purists.

The Selec-Trac reportedly has a 2.72:1 low gear ratio, the same as the Command-Trac part-time 4×4 system. If it is an electronic system, Jeep could likely make some Jeepers happier by dubbing it “Selec-Trac II” to avoid confusion with the 1983-2007 Selec-Trac. (Both systems had 2.72:1 low gears, but the Selec-Trac had a full-lock part-time mode, and used an open differential to avoid tire-scrubbing.) Chances are it is the more modern system, which is not seen as ideal by many Jeepers, but can increase gas mileage by disconnecting the front axle when not in use.

Export Wranglers are to get a 2.2 liter Fiat four-cylinder diesel — the same one used in current export Cherokees.

A dealer told Allpar source “Ruptured Duck” that JL Unlimited production will start this November, with the V6 engine only, before a Los Angeles reveal.  Two-doors should start in February. (These dates have not been confirmed with other sources and may be incorrect.) The Wrangler JK will accompany the JL in production for some time, as the new factory ramps up.

The four-cylinder Hurricane engine may become the base engine in  2018, and the VM diesel will become optional at that time.

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