Starting with a Wrangler platform, the Mopar Underground explored the idea of combining massive 40-inch tires with heavy axles, super-low gears, a 5.7-liter Hemi engine, and a manual six-speed transmission--with no lift whatsoever. The result is a stunning pit bull of a Jeep that screams power and performance in Red Eye No. 3 paint.
The tires are 40x13.50/R20LT Mickey Thompsons, mounted on 20-inch forged aluminum wheels. Stout Mopar axles--a Dana 44 in front and Dana 60 rear--were loaded with 5.38 gears and Dynatrac-prepared ARB air lockers to handle the rolling mass.
Power comes from a new 5.7-liter Hemi V-8, backed by a Getrag 238 six-speed manual transmission, both of which were installed at Burnsville Off-Road using an AEV kit.
Fitting the 40s required extensive bodywork, including trimming the rear quarter panels and adding fender flares that were one inch wider and four inches higher than stock. Since they were going to have to repaint anyway, they added a one-piece carbon-fiber hood and a chopped the top three inches, raking the windshield rearward another 10 degrees.
The interior is equally original. A rollcage was neatly integrated into the body tub and attached to the frame for safety. The center console and instrument panel were repainted to match the exterior, and the seats were recovered with two-tone Katzkin leather, front and rear. There is no carpet; the interior has been spray-lined with a bed-lining material, but Mopar floormats are used for mud control. The spare tire has been relocated to the cargo area, and a cargo basket installed.
The Lower Forty concept looks like a show vehicle, and it probably will end up on the auto-show circuit at some point. But it's a runner. During extensive thrashing on sand dunes in the Moab area, the Lower Forty concept willingly blasted up, down, and around every dune in the place. Eventually, the power-steering fluid began to overheat and a hose coupling gave way. It was fixed on site, and an hour later the Wrangler went back out for more.
SJ Mopar Madness
This immaculate machine is what happens when Jeep engineers get together to build whatever they can dream up. For starters, they transplanted a 6.1-liter Hemi V-8 into a clean 1978 Cherokee Chief body, along with a Mopar remanufactured 545 transmission. To that they added a Rock-Trac 4-to-1 transfer case from a Wrangler Rubicon. They also made use of the Rubicon's front and rear Dana 44 axles, plus they installed a 4.5-inch long-arm suspension kit. With the kit in place, 37-inch Goodyear MT/R tires can be used.
Body, bumpers, grille, and chrome trim pieces are conspicuously clean and perfect, looking just as they might have when the Chief came off the line in 1978. Inside, Mopar gauges have been added to update the control center, and custom leather seats provide the latest in seating style and comfort. To bring audio into the 21st century, a Mopar Kicker audio system has been installed.
Current Jeep engineers, and some retired ones as well, worked together to build a modernized classic 4x4 with power, gearing, and curb appeal that stops traffic on road and off.