Technical Articles Relating To Off-Road Vehicle Development

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2003 HD2500

 

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2003 HD2500

The inspiration for the suspension of this HD2500 can be found in the straight-axle desert-racing trucks of the 80’s. The goal is to create a workhorse of an off-road truck that is versatile enough to serve as a reliable tow-rig AND desert chase-truck. This vehicle is currently under construction at Johnson Fabrication in Riverside, CA.

The extensive rollcage was designed around the stock interior to retain all the amenities of an LT trim package. All materials throughout the truck are TIG-welded 4130 Chrom-Moly. The cab has been solid-mounted and the rollcage is tied-in directly to the frame through the cab in six places (at the A/B/C pillars). The rollcage also pierces through the firewall into the engine compartment and extends rearward into the bedcage.

The straight-axle conversion begins with a heavily-trussed Dana 60. We chose to use a Tera CRD60 housing and forged knuckles from Dedenbear, along with 35-spline Superior axleshafts.

That axle is located by a triangulated four-link with custom steering linkage. The front suspension should cycle between 14-16” of vertical travel using 2.5” Racerunner coil-overs and 3.0” bypass shocks along with hydraulic bumpstops and a custom anti-sway bar.

The rear suspension uses a custom spring-pack from Deaver along with another pair of 3.0×16” Racerunner bypass shocks and hydraulic bumpstops by Swayaway. Intended ride-height is only 4-6” over stock on 37” tires.

Glassworks Unlimited fibergass fenders are being installed to clear those 37” tires up front and depending on tire-to-bedside clearance in the rear, we may also install fiberglass bedsides.

The Duramax Diesel and Allison transmission will recieve a full compliment of performance upgrades. We’ve been looking into the diesel drag-racing market and following the Baja Bomber project in Four Wheeler magazine.

Look for this truck to be featured in Four Wheeler Magazine and related tech articles published online at fourwheeler.com.

10/11/05 UPDATE: Check out the progress

1/17/06 UPDATE: Recent Pictures