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Jeep Wrangler TJ - Mountainmuscle

Posted in Features on August 1, 2006
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True off-roaders know all terrains. And plenty of them utilize all terrains by having multiple vehicles tailored to each. Take John Currie of Currie Enterprises as an example. John has long owned rock rigs, desert rigs, and sand rigs, all of which he exercised regularly. But after multiple excursions in each, he came to the conclusion that one vehicle could easily do the job of many. After success with past Jeep creations, such as his "Strangler" Wrangler, and discovering how well they functioned as multiterrain vehicles, John came to the conclusion that a rig that was 1,000 pounds lighter with 100 more horsepower would serve his needs particularly well. And as a result, the Currie Rock Rod was born.

John's first thought was to go the rear-engine buggy route, but a desire to incorporate four seats and utilize an enclosed top kept pushing him toward the tried-and-true Jeep platform. With his ever-changing build plans still battling it out in his mind, John launched into his Rock Rod project by chopping off the rear section of a stock Jeep TJ frame and creating custom crossmembers and a new rear section. He topped the lengthened and narrowed frame with a custom-ordered Aqualu aluminum body that was narrowed to a 52-1/2-inch width and featured angled rocker panels, a TJ-style cowl, and the rear floor extended forward.

John acquired a GM 5.7L LS1 engine from Turn Key Engine Supply when he was still in buggy mode, but with its 400 hp and 420 lb-ft torque it wouldn't go to waste in his new Jeep creation. The mill uses Delphi electronics and an aluminum block and heads and was also equipped with a Vortec intake from a 6.0L pickup. The engine is cooled by an Airaid air filter, a Ron Davis radiator, and an electric fan, and also uses a Borla exhaust system. A full manual valvebody C4 transmission from Rancho Performance Transaxles uses a TCS torque converter and was installed behind the LS1 using an extra-short custom adapter from Advance Adapters. A lefthand-drop Atlas II transfer case was also installed and offers a 3.8:1 Low gear ratio and heavy-duty output yokes. A Winters ratchet-style shifter handles transmission gear selection, while a twin-stick shifter operates the Atlas II.

Being that the Rock Rod is a Currie-built rig, it's only natural that the axles would be unique and incredibly durable. In his constant quest to keep weight to a minimum and ensure maximum ground clearance, John opted to go with a set of Currie Enterprises' top-of-the-line aluminum Rock Jock Dana 60 axlehousings. The front received aluminum 1-ton steering knuckles along with 4340, 35-spline inner and outer axleshafts, 5.14 gears, and a Detroit Locker. Currie drive flanges were installed in place of locking hubs, and a 7570-T6 aluminum tie rod, drag link, and track bar were also employed. Steering power is provided by a Howe Performance steering gear and high-volume steering pump with a 4-inch firewall-mounted reservoir and is further aided by a Howe hydraulic ram assist. The rear Rock Jock diff is also equipped with 35-spline axleshafts, 5.14 gears, and a 1350 yoke. Both diffs are protected from rock scars with Rock Jock skidplates.

Using the Rock Jock axles as a foundation for the suspension design, John created a custom three-link front setup alongside a triangulated four-link rear configuration. The front and rear suspension use mid-length control arms constructed from 1-1/2-inch-diameter 7075-T6 aluminum. Six of the seven control arms are the same length and all employ forged Johnny Joint rod ends with left and righthand threads for easy adjustability. The link suspension setup was further complemented with a set of four coilover Fox Racing Shox valved to the proper specs and front and rear Currie Anti-Rock sway bars. The front shocks are 12-inch-travel units, and 14-inch-travel shocks are used in the rear. All of the shocks are 2-inch-diameter units with piggyback reservoirs and Hypercoil coil springs from Mirage Racing. With the 40-inch Goodyear MT/R tires mounted to 17x10 Walker Evans Racing beadlock wheels in place, a 102-inch wheelbase was obtained, as well as 23 inches of center ground clearance.

With much of the mechanical aspect of the Rock Rod complete, John moved on to the interior and exterior to give the vehicle its distinctive Currie-built flair. A custom TJ-style fiberglass hood from Campbell Enterprises was acquired and, along with the body, was coated with Electric Green paint by Miracle Design and also received red scallops. Dual upper and lower fuel tanks built by James Gang Racing were installed at the rear of the rig and hold approximately 18 gallons of fuel for extended expeditions. A Currie-built front bumper was also installed and houses a custom-painted Warn winch. The interior is entirely Spartan, but it isn't without the necessities. The aluminum dash is adorned with a selection of Auto Meter gauges to monitor engine vitals, and front and rear Beard Enduro seats are mounted to a custom 4130 rollcage built by James Gang Racing. Three-inch Crow lap restraints were also installed. John also has a narrowed windshield and frame, as well as a modified soft top for his Rock Rod 4x4.

Weighing in at just 3,300 pounds (under 3,000 pounds with sand tires) and creating 400 hp, John's Rock Rod project is a perfect example of how to plan, design, and build a multi-use 4x4. The vehicle more than exceeds John's needs for a variety of terrains, supplying substantial power and ability in the sand and handling fabulously in the rocks. It's part sand buggy, part rockcrawler, and part hot rod, but it's all Currie and all 4x4, and this rig is ready for just about anything.

Currie Rock Rod Wrangler
John Currie
Anaheim, California
5.7L GM LS1 V-8
C4 automatic
Transfer Case:
Atlas II 3.8:1
Currie Rock Jock Dana 60,
Detroit Locker
Currie Rock Jock Dana 60,
Detroit Locker
Three-link front,
triangulated four-link rear,
Fox Racing Shox coilovers
40x13.50R17 Goodyear
MT/R/17x10 Walker Evans

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