If you've been reading Diesel Power or Hot Rod magazine during the last year, you've seen the daily driver '03 Dodge Ram Quad Cab we built to run the quarter-mile in 11.76 seconds at Hot Rod's Drag Week. While an 860hp, 11-second diesel truck is impressive, Project X certainly wasn't the first diesel truck to do it.
Early on, we knew we wanted Project X to compete in all types of motorsports where its 5.9L Cummins could shine. Rather than build it into a dedicated drag truck, we want to keep it as a flexible platform that could cruise on the highway, knock down quick quarter-mile times, run more than 150 mph, and maybe even see some dirt-racing action. To achieve those multiple personalities, we knew we'd have to change around the suspension and drivetrain a tad. Our latest upgrade to the truck comes with the addition of a Gear Vendors overdrive unit.
-David Kennedy
Auxiliary overdrive units are generally associated with towing. Many times, when diesel trucks are hauling heavy loads up steep grades, they could really use a gear between the gears they have to stay in the powerband. Well, when it comes to racing, more times than not, winning comes down to selecting the right gear for each situation, too. Our Project X will be a great testimony to the versatility of a Gear Vendors overdrive unit. Not only will Project X be drag racing, but it will also be trying its hand in top-speed racing during the Texas Mile.
We sat down with Greg Hogue, Kirk Manuel, and Charlie Stewart to discuss some strategies for drag racing and the benefits of adding an overdrive unit as we began this project. They explained that a drag race, more often than not, is won and lost in the first 60 feet. Getting the mass moving in those 60 feet is extremely important, and adding gears will help us do that. With the current drag racing setup of Project X (3.73:1 rear-axle gears, 390/40R17 M&H drag tires, and a 0.69:1 Overdrive Fourth gear), the theoretical top speed is 117 mph. By adding the Gear Vendors auxiliary overdrive unit and changing the rearend gear ratio to 4.30:1, the new top speed is expected to be about 130 mph. That's an increase of 13 mph, but we are using a lower gear ratio, allowing for a quicker 0-60-foot takeoff.
While discussing this install project, we began to plan for the racing to take place during the Texas Mile. We used a simple mathematical equation to calculate the top speed coupled with a rearend gear ratio of 3.0:1 and our 29-inch-tall street tires. That gives Project X, in theory, a top speed of 145 mph. When we bolt on a Gear Vendors overdrive (0.78:1 ratio) to the factory Dodge overdrive (0.69:1), we get a combined overdrive ratio of 0.54:1 that should make the truck capable of a theoretical 186 mph.
At the beginning of the installation, we asked Tony Balliviero, master technician from Manuel Dodge in Fort Worth, Texas, to walk us through the process. During our discussions with Balliviero and Gear Vendors, it was decided that it would be best to switch the NADP-built 48RE automatic transmission's overdrive gearset to a four-wheel-drive version so we could bolt the Gear Vendors overdrive directly to the transmission instead of using the more common divorce-mount setup. This is not always necessary, but in the case of Project X's top-speed aspirations, it would be the best way to accomplish our goals with a single driveshaft. To make this happen, we started with the disassembly and will take you through all the steps.