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Diesel Power Articles

Diesel Power Straight Axle Swap, March 2009

WHAT KIND OF VEHICLE WERE YOU DRIVNG WHEN you were 18? How would you have liked to have been driving a diesel 4x4 with 10 inches of lift on 40-inch tires? Well, guess what? this '08 GNC Sierra 3500 HD belongs to 18-year-old Patrick Clark of Las Vegas, Nevada-the son of Pat Clark, of Pat Clark Pontiac and GMC, as well as Pat Clark Motorsports. From the very beginning, Patrick wanted to do something different with his new rig. Whether the truck was towing, hauling, of blasting through the dunes, he wanted to have the ultimate four-wheel drive.
     Patrick's stock '08 GMC HD nearly had it all. With the most powerful Duramax engine option available from the factory, arguably the plushest of interiors, and some of the finest creature comforts, the new GMC's are hard to beat, except for one fatal off-road flaw--independent front suspension (IFS). Although this isn't the first lifted Duramax-powered GMC Patrick has driven, it is the first one he's converted to a straight axle frontend. When deciding what to do with his latest truck, he and one of his dad's employees, Ron Reuchalski, came across Off Road Unlimited's website, and quickly realized what need to be done. So, the call was made to Maurice Rozo, owner of Off Road Unlimited in Burbank, California, who was more that happy to install on of his GM straight-axle suspension kits on a willing GMC owner, as well as some other trick off-road accessories.
     Thoroughly built would be an understatement for this truck. Eighteen-year-old Patrick races side-by-sides in the Championship Off Road Racing (CORR) series, so he's no stranger to the off-road world, and wanted a truck as capable off the pavement as it was on it. The straight-axle swap from ORU consisted of a Dynatrac Pro 60 axle, replacing the torsion bars of the factory IFS with a four-link system, 2.5 inch King coilover shocks with reservoirs, King bumpstops, limit straps, and two 2.5 inch King reservoir shocks out back. With 10 inches of total lift, Patrick's HD towers over his previous truck, and '05 3/4-ton with 6 inches of lift and 35-inch tires.
     Any time you build a capable off-road vehicle, tire clearance is an issue that needs to be addressed. Knowing that full suspension travel was a must, Rozo took the truck to a local autobody shop in Burbank. There, all four wheelwells were cut and re-worked to make froom for the 40-inch Mickey Thompson Baja Claws.
     The truck also recieved a host of other off-road-friendly components. Four Hella Rallye 4000 high-intensity discharge (HID) lights were mounted to the front bumper, and four more were added to the Denfeder light rack on top of the cab. While these units only consume 35 watts apiece, they can virtually light up the night, and illuminate much better than customary 100-watt halogen lights. From the rear of the truck, 12-volt power is available, and a Tire Gate replaces the tailgate and carries the spare 40-inch wheel and tire. Last, but not least, a 16,500-pound-capacity Warn winch was mounted behind the rear license plate in case the big GMC ever gets stuck.
     Off-road vehicles need power to blast through the dunes, so the next priority was getting more grunt out of the new LMM engine. The truck was taken to Pacific Performance Engineering, where a Dual Fueles CP3 injection pump system was installed and an Xcelerator programmer turned up the Duramax electronically, while a set of gauges was installed. A 4-inch turbo-back black-coated exhaust from Rolling Big Power was addes as well.
     The interior looks like the ideal cockpit for someone not content with staying on the high way. Four racing seats from Sparco woth four-point harnesses replace the factory captain's chairs up front, as well as the rear bench seats. Seeing a full rollcage is a serious off-road truck is always a welcome sight, and Patrick's truck is no exception. ITI Motorsports of Ontario, California, built the cage fro added Passenger safety.
     When we spoke with Patrick about having his truck built exactly the way he wanted it, he was adamant that not only would it definitely serve its purpose, it woould be put to the test often. Patrick told us that frequent trips to the sand dunes in surrounding states for off-road racing events, as well as dirt bike, ATV, and side-by-side riding are a regular part of his weekly agenda, and that this truck would be expected to haul and tow anything and everything. He then added that the GMC would also frequently. He then added that the GMC would also frequently make its way in and out of the sand and mud whenever he feld the need. With a 65-gallon Transfer Flow fuel tank, we don't think hauling his toys and playing around in the sand or mud several hundred miles away from home will be and issue.

The wheelwells were cut and re-formed by a body shop in Burbank, Californis, in order to accommodate the 40-inch tires. A set of 40x15.50R18 Mickey Thompson Baja Claw tires rides on 18-inch Pro Comp Alloy wheels. A Tire Gate from Wilco Products replaces the tailgate and holds the spare Mickey Thompson Baja Claw

Under the hood, a Dual Fueler CP3 fuel injection pump from Pacific Performance Engineering reduces drive load on the factory CP3 and, in conjunction with a PPE Xcelerator programmer, provides plenty of additional horsepower to get this monster moving.

Hidden behind the rear license plate is a Warn 16.5ti winch. Thanks to Tuff Stuff Products in Stoutland, Missouri, the hinges on the back of the rear license plate can snap to the winch fairlead. Also notice the Class V hitch, which will come in hand when Patrick decides to load up a trailer with any combination of toys.

The four-link straight-axle kit from ORU comes with 2.5 inch diameter King coilover shocks and hydraulic bumpstops, extended brake lines, and limit straps.

The Dynatrac Pro 60 front axle is equipped with an ARB Air Locker, 35-spline 1.5 inch axleshafts, and an Off Road Unlimited finned differential cover. Also notice the hydraulic ram-assisted crossver steering that eliminates the need for a dropped pitman arm, the sway bar for roll control, and the aluminum track bar, which eliminates bumpsteer.

The spotless underbody was laced with trick aftermarket parts. ORU outfitted the stock transfer case with a fixed front dirveshaft yoke, and ARB on-board air compressor mounted along the framerail, and a 65-gallon Transfer Flow fuel tank, which replaces the factory tank. The 4-inch RBP exhaust runs parallel on the left.

Four racing seats with four-point harnesses from Sparco were installed in the interior, and Twisted Stitch outfitted them with seat covers. The four-point rollcage from ITI Motorsports was installed in the back of the cab.

From the rear, you can see the 2.5-inch King reservoir shocks, the factory AAM 11.5-inch rear axle, and a 12-volt power source. ORU also stripped the underbody coating from the frame and painted is glass black.

Eight 35-watt Hella Rallye 4000 Euro Beam high-intensity discharge lights, four and the bumper, and four on the Defender light cage, provide all the visibility one could ever ask for while off-roading at night.
Full Story  | Posted in GMC

Diesel Power Best of Diesel Annual 2013

IT'S FUNNY HOW ONE COMPONENT CAN MAKE OR BREAK THE IMAGE of a truck. When General Motors announced in 1991 thats its 1-ton pickups were switching to independent front suspension (IFS), there was a cry heard around the world. That cry was for the loss of the Dana 60 front axle that had been fitted to every four-wheel-drive 1-ton GM pickup since 1977. That cry still echoes to this day.
     Ford and Dodge truck engineers must have rejoiced over the news. For in the heavy-duty-truck market, there's no subsitute for the simplicity, strength, and reliability of a solid axle. Maurice Rozo of Burbank, California, couldn't agree more. As a Chevy guy, he cringed at the loss of the Dana 60 axle in the GM lineup. Unlike the rest of us who could do nothing but complain about it, Maurice came up with a solution. He built his own GM solid axle suspension kit.



     Working with a team of fabricators and designers at his shop Off Rod Unlimited (ORU), Maurice spec'd out a kit that would allow '92-and-newer GM 3/4-and 1-ton truck owners to install a Ford style Dana 60 front axle in their truck utilizing commonly available leaf springs. Off Road Unlimited made a name for itself offering this kit to the public, as well as developing other proven off road suspension, steering, and drivetrain products.
     Over the years, most of the solid front axle GM trucks that you've seen on the road are either running ORU parts, or appear to have taken cues from the ORU kit. We've even seen Jim Carrey, the famous actor, driving a 3/4-ton solid axle GM truck that Off Road Unlimited built.
     Recently, Off Road Unlimited has revised its solid axle swap kit to not only work with General Motors' latest GMT900 3/4-ton chassis, it's now developed a package that includes a four-link suspension and coilover shocks for '01-and-newer trucks.



     It's had to believe, but Maurice's "Red Addiction" Chevy began life as a two-wheel-drive truck. After years of doing more solid axle swaps that anyone else, the one thing Maurice has never been completely satisfied with is the New Venture Gear transfer cases that the '01-and-newer Duramax trucks come with. Since Maurice knew he was going to ditch all the factory four-wheel-drive components, he figured he should just start with a two-wheel-drive truck instead.
     Maurice ordered an '07 Silverado 2500HD with the LMM Duramax and Allison 1000 transmission. His solid axle upgrade kit is designed to work with both two and four-wheel drive GM truck frames, so that only left fitting the truck with a transfer case. For that, Maurice made a call to Advance Adapters, in Paso Robles, California, and ordered an Atlas II Transfer case with a 3:1 low-range.
     Now, the Duramax's torque is transfered through the stock two-wheel-drive Allison 1000 six-speed transmission and sent back to a divorce-mounted Atlas transfer case. From there, the power is sent through a pair of driveshafts to the AAM 1150 rear and a custom-built Dynatrac Pro 60 front axle bolted in with ORU's latest four-link front suspension kit.



     The gross axle weight rating (GAWR) of the GM 3/4-ton independent front suspension is 4,600 pounds. That means the front end is rated to support a little more than 2 tons, which gives and indication of the strength and durability of GM's IFS. A Dana 60 axle, on the other hand (one built to the specs of the Dynatrac Pro 60 in Maurice's truck), has a GAWR of more like 5,500 pounds giving it 900 pounds more capacity to take a pounding without breading so much as a sweat.
     We can attest to the strenth of Maurice's 2500HD as we drove to 200 miles to our cover photo shoot, watched Maurice beat on it, and then drove it 200 miles back hone. Nothing we could do to the truck phased it in the least, and the truck came home needing only a new rear bumpstop, a fresh tank of fuel, and a good truck wash. Now that's what we call heavy duty!

A Dynatrac Pro 60 Front Axle with an ARB Air Locker, 4.56 gears, 35-spline axle shafts, and Off Road Unlimited ram-assisted crossover steering feeds Maurice's solid axle additcion.
The Pro 60 axle is located by Off Road Unlimited's new four-link solid axle conversion kit that features 2.5" King coilover shocks, hydraulic bumpstops, a sway bar, and limit straps.
For off -road use, Maurice's 2500HD runs on a set of 40-inch ProComp Xterrains mounted on 17x10 ProComp wheels fitted with Champion C-3 style beadlocks.
The LMM Duramax has been treated to a PPE Xcelerator tuner, a Banks cold-air intake, and DPF-back exhaust. Maurice feels the throttle response is a little lacking on the new LMM engine and will be working with PPE to address that issue for off-road driving.
The rear AAM 1150 axle has been fitted with 4.56 gears, an AAM Tracrite helical-gear typs limited-slip differential, and and ORU finned aluminum differential cover. From this angle, you can also see the Gale Banks Engineering dual exhaust, King reservoir shocks, Atlas leaf springs, and the mount for the hidden Warn winch that's stashed under the pickup bed.
In the Line-X protected bed, Maurice carries a Transfer Flow auxiliary fuel tank/toolbox and a Power Tank Co2 bottle for airing up the tires.
Under the hidden flap in the floor of the bed is a warn 16.5ti winch.
The truck sas built with an off-road friendly LS cloth interior that's been updated with a Grant steering wheel and a custom mount for the cable-actuated transfer case shifters and ARB Air Locker switches.
Full Story  | Posted in Chevy