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Project Excursion Killer, Part 2Building the suspension, steering, and drivetrain. From the February, 2009 issue of 4Wheel & Off-Road By David Kennedy Photography by David Kennedy
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Last month we scared Blue Oval fans everywhere by waving the Bow Tie banner and showing you how we swapped a new 8.1L Chevrolet engine into our Suburban pre-runner. This month we wanted to get deep into the buildup of the truck to expose you to some of the desert race technology we used that you could easily apply to your own rig to make it better. We don't expect to see all of you entered in the Baja 1000 next year, but there is something here for everyone. Remember, even though it looks like a '01 Suburban there is actually a '73 GM pickup frame hiding under all that chromoly tubing. We continue this month by showcasing the craftsmanship of Off Road Unlimited (ORU) in Burbank, California, as they construct the suspension, steering, and drivetrain of a '01-bodied, '73-chassis Suburban. Next month we plan to wrap up the whole project with an in-depth feature of the vehicle in action, showing off the truck as we rip across the desert. We're already exercising our throttle leg in anticipation.  In Part 1, we left you guessing...  In Part 1, we left you guessing how to make the factory fuel injection work. Originally we planned to use the stock 8.1L computer, but knew it would have a fit when we transplanted the engine to its new home. The secret to our success was Alan Tehan from Precision Automotive, and this little fourth-generation engine control module. Tehan stepped forward and saved our skin by programming this super EFI computer to work with the factory sensors and injectors on our engine. When tuned by Precision Automotive this is arguably the most advanced (and affordable) EFI controller on the market and will run anything from a TBI four-cylinder to a TPI V-12 in a speed density mode. You can run a distributor or a coil-near-plug ignition system like our 8.1. The system has two separate timing tables so it can retard or advance the ignition timing for different octane grades of fuel. It can control staged nitrous and work with forced-induction engines up to 15 pounds of boost.  The 8.1L fit so well it looked...  The 8.1L fit so well it looked like it was born in the engine compartment. We knew that the engine would see some of the dustiest environments in the world so we spoiled it with this air cleaner from Unique Metal Products (UMP). The air filter canister sits in the passenger compartment and is connected to our BBK throttle body with a 4-inch-diameter intake sectioned out of mandrel-bent aluminum tubing welded together by the masters at ORU.  Driving off-road can send...  Driving off-road can send a lot of debris and trash through the radiator of a truck. Get a leak in the middle of the desert and you could be one cooked wheeler by the time you get back home--if you make it. For years dirt racers have been mounting the radiator in the rear of their trucks to let it get a flow of cool air without being so vulnerable. ORU installed this mattress-sized Griffin radiator in the back of the Sub and tacked on a Flex-a-lite twin-fan unit to make sure air gets sucked through the aluminum cores even at idle and through the slow sections. Underneath the radiator is a 70-gallon fuel cell that Fuel Safe made custom to our specifications. The cell sits low in the chassis and gives us enough room to mount the two 37-inch spares in the Pyrotect tie-downs.  Here is a ground's-eye view...  Here is a ground's-eye view of the twin Fluidyne coolers and integrated electric fans. The one on the left holds 2.01 quarts of engine oil and the one on the right holds 2.01 quarts of ATF. These coolers draw air from in front of the radiator and cool 800hp Trophy Trucks all race long, so they should be overkill in our truck. All plumbing chores use Goodridge products, which we got from Orme Brothers.  To keep tabs on all that happens...  To keep tabs on all that happens in the engine room, we ordered a set of Auto Meter 25/8-inch liquid-filled Ultra-Lite gauges (fuel pressure, oil pressure, oil temp, water temp, and volt meter). ORU grafted them into this hand-formed piece of aluminum to form a clean dash for the truck. These gauges match our 5-inch memory tach that's mounted in the driver's line of sight, are dead-on accurate and easy to read on the fly, and add very little weight to an already rotund truck. To keep everything together and within reach of the driver, the switches for the starter, fuel pump, electric fans, and even running lights are all grouped together.  To feed 496 cubes you need...  To feed 496 cubes you need to pump a lot of fuel. We called up Summit Racing to order this A1000 Aeromotive electric fuel pump (PN AEI-11101), capable of 500 gallons per hour, and matching high-flow filter (PN AEI-12301) in case we get any grime in the tank during fill-ups. The pump was mounted inside the driver-side framerail to protect it from getting whacked, and plumbed with -10 fuel line to the Aeromotive bypass regulator (PN AEI-13101). One of the two Optima yellow-top batteries sits right above the pump to supply it with consistent voltage under any circumstances.  As we mentioned last month,...  As we mentioned last month, our Sub is going to run IFS. To send power to the wheels, ORU came up with this slick Jaguar rear Dana 44 centersection that would allow them to use proven Dana 44 gears and lockers. These centersections have a machined mounting pad on top that works in conjunction with two side mounts to keep it located high in the chassis. We didn't want to have any problems with this frontend so we stepped up and ordered a set of 4.88 gears from U.S. Gear and an ARB Air Locker. Next month we'll show you the trick CV shafts and joints and how ORU made it all work with Dana 60 hubs, spindles, and stub shafts.  Here is how the construction...  Here is how the construction of the front A-arms began. Because there is not a single design that works for all trucks, ORU designed and built the lower A-arm from 3/16-inch steel plate and then mocked up various upper A-arms to test for bumpsteer and suspension travel. All suspension pivots use Aurora Bearing rod ends, and the Dana 60 knuckles pivot in uni-balls.  The front suspension is controlled...  The front suspension is controlled by single 14-inch-travel King 21/2-inch-diameter coilover shocks with reservoirs and 400-pound over 550-pound coil springs. Ride height can be adjusted from side to side with the blue anodized shock collars. To slow the mighty beast, ORU mounted up a set of its 121/2-inch slotted rotors that get squeezed with Wilwood six-piston fixed aluminum calipers.  The AAM 14-bolt rear was heavily...  The AAM 14-bolt rear was heavily gusseted and plated by ORU to eliminate any chance of bending the housing. The rearend enjoys the same brake treatment as the front for ultimate braking power and to limit the number of spare parts carried. Rear gears are 4.88s and put traction to the ground through a Detroit Locker from West Coast Differential. To keep the gear lube from cooking, an ORU aluminum differential cover was added to dissipate the ever-present heat monster.  The rear four-link trailing-arm...  The rear four-link trailing-arm suspension was built with 60-inch-long arms that pivot off bushings mounted to the stock GM frame to mount the King 2 1/2-inch-diameter, 16-inch-travel coilover shocks with reservoirs and 400-pound over 500-pound coil springs. To make the world feel flat and smooth, 2 1/2-inch-diameter, 18-inch-travel bypass shocks with reservoirs were added on each side to flatten the bumps better than a Caterpillar steamroller.  Making the steering work without...  Making the steering work without bumpsteer in a configuration that will hold up to hours of bashing under the merciless weight of 37-inch tires, ORU designed this one-off dropped bell-crank steering out of 2x2-inch square-tube steel that rides on Delrin bushings. The system receives input from a Lee Manufacturing steering box and hydraulic ram assist fed by the rebuilt 8.1L power steering pump.  To get the truck to handle...  To get the truck to handle as well as possible at high speeds, we are running an almost 8-foot track width in the front. To fit that much width under the body required a front fiberglass clip from Hannemann which was then widened and contoured to fit the truck. The suspension was cycled one more time to make sure the tires wouldn't contact anything at full stuff or full lock before we even thought about paint. You don't bring a truck like this to the body shop; after each piece of the body was test fitted, it was sent out to a local sprayer to get squirted a speed-friendly color.
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