Going Nowhere Fast

Future Shocks

The hardest-working men at the test are a trio of Swedish engineers who are baby-sitting the brand-new shock absorbers, two per wheel, dubbed T Rex because they're bigger and tougher than anything hlins Racing has ever developed. Although the unit had been tested comprehensively in the firm's factory in Sweden, it isn't performing as expected here in the Mojave Desert. To find out why, Johan Jarl, the lead engineer on the project, takes a ride with Pflueger. The experience leaves him dazed. Smiling wanly at Pflueger, he says, "His body must be made of different stuff than mine."

To this point, Pflueger Racing had been using ultra-heavy-duty shocks built by small companies that specialize in this rarified arena. But Pflueger wanted to leverage the R&D resources and racing expertise of hlins, which makes shocks for Formula One, Indy, the Nextel Cup and the World Rally Championship. So in 2004 he flew Magnus Danek, the company's chief automotive designer, to the U.S. and terrified him with a thrill ride around the Nevada desert to persuade him that off-road racing was the ultimate proving ground for shock absorbers. Danek left Nevada suitably convinced.

Shock absorbers don´t really absorb shock. They damp, or control, the energy of the springs. Typically, the damping force is provided by a piston drilled with small holes that telescopes up and down in a tube filled with gas-charged oil. As the piston cycles back and forth, it can create air bubbles that degrade shock performance. If the movement is especially violent, the hydraulic fluid can get so hot that the shocks burst into flames.

hlins has solved the heat problem in two ways: by carefully controlling the pressure of the oil in the shock and by adding little fins on the outside of the shock to dissipate heat. As the oil flows through the shock, a fiendishly complicated collection of teensy pieces called a shim stack controls the internal flow of hydraulic fluid. At the same time, hlins built a remote reservoir for the hydraulic fluid and sheathed the tubes connecting it in artistically finned aluminum extrusions. "Conventional off-road shocks have gotten bigger and bigger over the years, but they´re basically at the end of the road," says Hoffman, the team´s resident shock expert. "By comparison, the hlins are rocket science."

The real trial comes on the second day of testing, when the shocks are dialed in and integrated with Harris´s newfangled suspension. In back-to-back runs, the new truck is quicker and more predictable than the old one. "I don´t know if 'boring' is the right word," Pflueger says, "but the new truck is so easy to drive that that's almost what it is. With the old truck, I'm always busy working the steering wheel and the throttle. With the new truck, I just point it where I want to go and hit the gas pedal. It drives like you took it off the showroom floor. I could race it in Mexico right now."

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