Building a mild-mannered SUT to tackle Baja
Honda Motor Company has nothing to prove in the desert-at least on two wheels. In the last decade alone, factory-backed Honda motorcycle teams have notched nine straight wins in the Baja 1000. It would be hard to count just how many other off-road races have been won by riders astride Hondas, whether factory-backed or privateer.
Yet in 2005, Honda had a different desert-race goal in its sights. Faced with a mixed reception to its all-new Ridgeline pickup, Honda decided to prove its truck's mettle by entering one in the grueling Baja race. Many truck makers over the years have traded on the cachet that comes with south-of-the-border desert competition, and Honda no doubt figured the Ridgeline could get a nice boost by surviving one of the toughest challenges in all of motorsports.
Rather than start a truck-race program from scratch, Honda sought partners with experience in the desert, especially in the area of turning production vehicles into competition-ready machines. Clive Skilton and his son, Gavin, seemed perfectly tailored for the job. Originally with Don-A-Vee Motorsports (which has since become California Race and Rally, or CaRR), the Skiltons have spent some 15 years prepping and racing unibody Jeeps, and Clive now heads the JeepSpeed racing series. Another of Skilton's sons, Darren, successfully transformed Kia SUVs into desert race trucks that weren't just competitive; they notched an impressive series of wins.
Gavin Skilton headed up the Honda race effort for CaRR; and to build the truck he assembled a team of desert-race veterans, including fabricator Jason La Fortune and his crew at Temper Mental Racing.
With its years of experience in race series as diverse as motocross and Formula 1, Honda probably could have fielded a super-exotic, Ridgeline-based Trophy Truck and gone on the hunt for an overall win. But that wasn't the point of the exercise; showing off the Ridgeline's inherent capabilities was. So the CaRR truck was entered in SCORE's Stock Mini class, which allows only limited modifications to production trucks.
To underscore the "stock" in Stock Mini, the truck delivered to the team wasn't some stripped, body-in-white shell, but a fully trimmed, ready-for-the-showroom-floor Ridgeline. That meant the team's first order of business was to put the pickup on a strict diet. Out came the truck's interior ("the rear seat weighed a ton," Skilton said), carpeting, sound insulation, airbags and window glass. The Ridgeline's innovative underbed "trunk" was removed in the interest of ground clearance; later, that hole would be filled with one of the truck's two spare tires.
Skilton figured they removed between 600 and 800 pounds from the truck. Most of that weight would be added back, though, with the addition of the rollcage, fuel cell, spare tires, jack and tools, bigger wheels and tires, and so on. SCORE's rules, in fact, call for the truck to race at its "as delivered" weight, "and with everything we have to add to the truck, it probably won't be underweight," Skilton said early in the process.
With much of the truck stripped to the metal, the team found the Ridgeline's unibody surprisingly well put together. "It's strong enough that the rollcage will be there just for safety, and not to hold the unibody together," said Skilton. Honda engineers, in fact, report that the Ridgeline's unibody has 20 times the torsional rigidity of a conventional body-on-frame configuration.
The full rollcage, made from 13/4-inch, 0.120-wall chromoly, provided a cocoon for the occupants and the 26-gallon ATL fuel cell. Downbars front and rear tied into the suspension mount points to give them added strength, while an additional set of bars wrapped around the engine and through the grille to mate with the chromoly front bumper. Later, that bumper would serve as an attachment point for one of several additional skidplates under the Ridgeline.
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In a race truck, "the suspension is everything," Skilton believes. "It all revolves around the suspension. No matter how trick the engine is, if the truck can't handle the bumps ...." He left the rest unsaid.
Suspension tuning is one area where the SCORE Stock Mini rules are somewhat relaxed. The truck's original suspension configuration must be retained, and there are limits to the number of shocks used per wheel and to where they can be located (not through the hood or above the bed floor in the rear). Within those parameters, racers are free to modify springs, shocks, and struts.
As it turned out, Skilton loved the stock Ridgeline's handling, praising its fully independent suspension for its carlike ability to stick to the road and handle curves. When it came time to upgrade the suspension, he didn't want to change its geometry at all. The goal instead was to come up with components that would live in the jarring Baja environment, provide a bit more wheel travel and give the truck additional ground clearance.
Skilton turned to King Racing Shocks for help with the componentry. The rear end was fairly straightforward-slightly firmer, taller springs, and 3-inch remote-reservoir shocks fit nicely into the stock location.
The front was another matter entirely. The Ridgeline is fitted with MacPherson struts, and King had never built a racing version of a strut-until now, anyway. By combining off-the-shelf components and custom fabrication, King built prototype struts using 3-inch shock bodies with massive 1 1/4-inch shafts (which are normally 7/8 inch in a 3-inch can); dual remote reservoirs; adjustable spring-mount collars; and coil springs rated at 350 pounds, nearly double the stock rate. "That'll give us the height and strength we need in front" to help lift the truck over obstacles, Skilton said.
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The key to making the strut work was a custom-built strut top with a 5-inch thrust bearing. "Everything moves with a front strut," Skilton explained, holding the top of the strut in his hand and rotating its body in a circle. "So our custom bearing cup allows this movement but protects the bearing from dirt and dust."
Because the King struts were longer than stock, their top mounts had to be moved up out of their stock location to triangulated mount points built into the rollcage. The difference in mount height is only a couple of inches, but it made a difference in terms of wheel travel-now 8.5 inches-and ground clearance. Between the new suspension and the nearly 32-inch tires CaRR planned to use in the race, the Ridgeline gained about an inch and a half of altitude between it and the desert floor.