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Straight to the Top

Front Shot Coming Over Hill Front Wheels In The Air
James J. Weber | Writer
Posted December 16, 2002
Contributors: Randall Jachmann

Off Road Unlimited's Straight Axle Suburban

Let's face it, there's just something about a straight axle truck that really gets the blood flowing. That feeling is exactly what evoked Off-Road Unlimited's Maurice Rozo to create a GM IFS-to-straight-axle conversion kit for the '01 Chevrolet/GMC Suburban. Developing a solid-axle conversion kit for the new GM trucks was something the ORU crew was familiar with, as the company also offers a conversion kit for the previous-generation '88-'98 Chevrolet/GMC trucks.

To showcase its conversion kit for the new generation Silverado, Maurice and company obtained an '01 3/4-ton 4WD Chevrolet Suburban. Bulletproof and reliable, the Chevy was intended to serve as both a tow vehicle for Off Road Unlimited's one-of-a-kind '01 Chevrolet Suburban prerunner and as a support vehicle for the crew. Once the factory independent front suspension was removed, the frame was cleaned and prepped for surgery.

Because the straight axle conversion kit was designed to accommodate varying amounts of leaf-spring lift, Maurice's crew went with an 8-inch lift. With the new mounting brackets and hangers attached to the strengthened frame, a freshened Dana 60 front axle, complete with 4.88 Drive Train Direct gears and an ARB Air Locker, was slipped under the Suburban and hung on the custom fabricated 8-inch lifted National Spring spring packs. The front axle stubs were upgraded from the usual 31-spline units to stronger 35-spline units. To decrease the front drive shaft angle, the diff housing was rotated.

Speaking of the front driveshaft, High Angle Drive Train of Paradise, California, replaced the factory 'shaft with a long-travel conversion unit with equal-length compression connections and a 1350 1-ton CV joint. Once installed, the 10-spline, heat-treated shaft offers a full 6 inches of extension and compression, which keeps the driveshaft from bottoming out and breaking the transfer case adaptors.

The speed-balanced driveshaft is mated to a Pro-Comp transfer case output shaft, which is attached to an NP 263 transfer case from an '01 HD-Series Chevrolet truck. The original transfer case was replaced because it had GM's Autotrac feature that allows the front driveshaft to engage automatically, thereby causing excessive wear and tear on the drivetrain components.

As part of the conversion, the factory steering system was altered for the better, thanks to the addition of Off Road Unlimited's ram-assisted crossover steering system.

Added control in the corners comes via the replacement of the factory antisway bars for solid Off Road Unlimited units that were installed on both the front and rear axles of the Suburban. Complementing the newly installed straight axle are Off Road Unlimited's dual front shock hoops, which hold a pair of polished 2.5-inch diameter King Racing shocks with remote reservoirs that damp 12 inches of travel at each wheel. The finishing touch was the polished Off Road Unlimited front differential cover that went over the inner workings of the Dana 60.

While the rear suspension did not require a conversion package, a few additional items were installed to bring it up to par with the frontend setup. For starters, the factory leaf packs were replaced with 8-inch lifted National Spring units. Keeping in mind that the Suburban would be used primarily for heavy-duty towing purposes to, from, and across the blistering hot desert, a pair of Firestone airbags was sandwiched between the frame and leaf springs with custom-fabricated Off Road Unlimited mounting brackets. When the 'bags are aired up and the single 2.5-inch-diameter King Racing shocks with remote reservoirs are damping the ride, it is as smooth as silk.

The OEM 14-bolt axle with 4.88 gears was treated to a Detroit Locker and chrome-plated Off Road Unlimited differential cover similar to the unit at the front of the vehicle. The final touch was the replacement of the factory driveshaft with a 1-ton 1350 CV-jointed unit.

Power to the Suburban is delivered via a 345hp 8100 Vortec V-8 engine that has been decked out with a Hypertech Performance Chip that's good for 25 additional horsepower. A 3-inch stainless steel Borla exhaust system and a Granatelli mass airflow sensor adds yet another 10 horses. A K&N Filtercharger System purifies all incoming air for the most effective performance.

The landing pads for this monster are 37x12.50R17 BFGoodrich Radial Mud-Terrains mounted onto 17x10-inch Weld Racing Typhoon wheels. Entering the vehicle is made easier via four Kodiak electric steps. Completing the overall exterior appearance of the Suburban is a pair of 8112 PIAA lamps mounted atop a custom fabricated Off Road Unlimited light bar located just in front of a Street Scene aluminum grille insert.

The interior has been left relatively stock for now, but Maurice does plan on installing custom seats and a custom audio/video system for additional creature comforts during those long tows home from a day of prerunning. To reduce heat build up within the cockpit, the windows were tinted.

Living up to its name, the Off Road Unlimited team has proven by the form, fit, and function of this Suburban that there are no limits to how far true off-road enthusiasts will go in order to produce a vehicle that is capable of meeting -- and often exceeding -- their expectations, both on and off the trails. For those of you still wondering what it takes to go straight to the top, might we suggest a Dana 60 and an Off Road Unlimited conversion kit? Just a thought.

specifications
Owner/hometown: Maurice Rozo, Off Road Unlimited/Burbank, California
Vehicle : '01 Chevrolet 3/4-ton 4WD Suburban
Suspension : Off Road Unlimited IFS-to-straight-axle conversion Kit; 8-inch national spring leaf spring suspension; Firestone airbags (rear); Off Road Unlimited Double Shock Hoops (front)
Transfer case : New Process 263
Tires : 37x12.50R17 BFGoodrich Mud-Terrains
Wheels : 17x10-inch Weld Racing Typhoons
Shocks : 2.5-inch King Racing shocks (front & rear) with remote reservoirs
Engine : Vortec 8.1 Liter V-8
Other modifications :Off Road Unlimited steering system; Borla exhaust; K&N filter; Street Scene grille; Off Road Unlimited antisway bars; ARB Air Locker; Drive Train Direct 4.88 gears(front); OE 4.88 gears (rear); Custom driveshafts from High Angle Drive Shaft (front & rear); Kodiak steps; PIAA lights; Hypertech performance chip; Granatelli mass air flow sensor; Pro-Comp transfer case output shaft

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