On common ground:Designed and purpose-built for diverse ends of the off-road motorsport spectrum, a title-bound rockcrawler and a championship-winning Trophy Truck share more techno-design and state-of-the-art components than you would ever imagine.
Form follows function is a concept often associated with military and performance aircraft, sophisticated NASA spacecraft, state-of-the-art hydroplanes, and even a seemingly basic item like a handtool. Form follows function, simply put, is a design philosophy where everything is about function, and the shape of the component is dictated by performance, and nothing else. In the world of recreational and professional motorsport, function before all else is also on display in the form of purpose-built 4x4s.
And what is a purpose-built 4x4? It's a strictly functional machine, fabricated with zero fat; without even a single part installed that wasn't 100 percent dedicated to the cause of winning. However, the definition of purpose-built is forever in flux; it must be since technology, improved aftermarket performance accessories, and necessity, are constantly challenging current notions of what is - and what is not - possible with a performance-bred 4x4. For example, who among us could have predicted the extreme suspension and chassis designs used on todays top rockcrawling machines? And what about open-course, Baja-style race trucks? Though many focused engineers had made all-out attempts to design a front drive axle system to go with the proven rear drive setup, reliability issues with the front CV joints had always been the downfall of 4WD Trophy Trucks.
The point is that the chosen arena, current technology, and the available components dictate how best to set up any particular 4x4. Obviously, a rockcrawler doesn't require a desert truck's ungodly horsepower, just as a desert truck would instantly shred a 'crawler's gum-sticky treads. Interestingly, there is overlap in the components used on purpose-built 4x4s. Just a few years ago, exotic shocks, chrome moly, and suspension linkage systems were seen only on high-end desert trucks and Indy cars. These days, sophisticated suspension components, costly metals, and radical chassis geometry are now de rigueur on all the top rockers.
With the concept of purpose-built 4x4s firmly in mind, we set out to discover - and commit to film - two fine examples of the form follows function concept. When we hooked up with Avalanche Engineering and Terrible Herbst Motorsports, we knew we had hit the mother lode of function. Check out these two wildly diverse examples of high-end 4x4s, and marvel - drool, even - over the sophistication, the incredible fabrication, and the shared motor sport bloodline.
Avalanche Engineering's AssassinMission statement: To Boldly Go Where No 4x4 Has Gone BeforeSimilar to many revolutionary motorsport concepts, the design for the Assassin began when Steve Rumore sketched the initial lines of a radical, purpose-built 'crawler on the back of a cocktail napkin. That rough blueprint was far from polished, but the concept was sound: build a single-seat 4x4 that was virtually unstoppable on any competition rockcrawling course. And unstoppable the Assassin has been, racking up a Sixth Place finish during it's first outing, followed up by a Second Place finish a few weeks later. After a DNF because of mechanical teething problems, the next event saw Steve and Drew Barber - the Assassin's chief fabricator - finally get the 4x4 dialed in, and Steve and the Assassin dominated, grabbing the top spot on the podium. With that initial win, the Assassin is poised to make a championship winning run during next year's national rockcrawling series and has clearly defined what a purpose-built rockcrawler must be.
Terrible Herbst Motorsports F-150 Trophy TruckMission statement: To Cross Wicked Terrain Faster Than Thought Possible with a 4x4Mike Smith and his talented crew at Terrible Herbst Motorsports know precisely how to research, design, and fabricate a race-winning desert truck - they've been doing so for more than 20 years. But the challenge of building a 4x4 with a sophisticated long-travel suspension and great gobs of power really put the crew's focus and determination into overdrive. It wasn't enough to merely fab a functional 4x4 Trophy Truck, the machine had to be reliable, flat-out competitive, and driveable at it's projected top speed of - get ready - 138 mph. The Terrible Herbst Ford F-150 is all that and more, thanks to a 700hp big-block Blue Oval backed by a six-speed electronic sequential gearbox, and wheel travel that's measured in feet, not inches. The real key to the truck's numerous race wins this season has been the 4WD system, which puts the V-8's power to the ground through all four tires like nothing you've ever seen.
Suspension Science:Beyond Radical
As noted, there is some degree of crossover between the various sub-systems of the Assassin and the Terrible Herbst Motorsports truck. Although Herbst's Mike Smith basically scratch-built the entire F-150, the shocks and dampers from both vehicles share fundamental design elements. The rear suspension on each vehicle can also be traced to a common starting point, though Smith has taken the Ford's suspension to an unbelievable level of sophistication.
A strong, lightweight, and durable chassis is crucial in either rockcrawling or high-speed desert blasts. Both the Assassin and the Terrible Herbst Ford use chrome-moly tubing for the frame since it's the best material for the job.
Horsepower;More or Less
One area where the Assassin and the Terrible Herbst truck differ is in their choice of motorvation. While the Trophy Truck needs all the torque it can get to blast through soft sand and past competitors, the Assassin only requires enough power to ease it over the craggy rock terrain.
Wheels and tires are obviously of major importance, whether the speed is fast or so-slow. Once again, crossover is evident - not in rubber compound, but in tire sizing and by the way the tire is clamped to the wheel.
As you can see from the design and execution of the Assassin and the Herbst Trophy Truck, purpose-built and form follows function are more than casual buzzwords or abstract concepts to those who pride themselves on the precision craftsmanship of motor sport 4x4s. Although this story is a mere glimpse into the extreme edge of wildly functional 4x4s, let it serve as inspiration to all enthusiasts who modify their trucks in a true purpose-built manner for sporting use.