Chris Theodore remembers the very frame in the 1966 Frankenheimer epic “Grand Prix” that inspired this project. “I saw the Lotus 33 in a front-three-quarter view and thought: That’s the car where Colin Chapman attached the suspension directly to the powertrain and used a monocoque tub. Too bad he had to ruin the torsional rigidity by cutting a hole in the tub for the driver’s head.” Soon after, the lifelong engineer/inventor (he’s innovated at Ford, GM, AMC, Chrysler, Saleen, ASC, and others) started sketching a design for his Uni-Chassis – a unitized powertrain, chassis, and suspension. Theodore is known as the father of the Ford GT supercar, and hence his initial noodling and doodling incorporated the GT’s front and rear extruded-aluminum bolt-on crash structures and its suspension hardware, tied together with bespoke castings to which the GT’s engine and transmission would mount (engine in front, transaxle in back), connected by a structural aluminum tube.
He’s a savvy engineer, and all his initial calculations suggested this concept could work, but just to be sure he bounced it off trusted colleagues like former Chrysler engineering veep Francois Castaing and ex-Ford and Porsche chassis guru Manfred Rumpel. Nobody could find any fatal flaws in the Uni-Chassis design, so he patented it and sweet-talked Ford into selling him a ratty, crusher-bound GT prototype along with the CAD data that helped create it.
After several computer design iterations of bulkhead and bell-housing castings and backbone tubes, the optimal design turned out to be an 8-inch-diameter, quarter-inch-thick extruded aluminum backbone tube that, when all bonded together, results in torsional rigidity of 13,000 pound-feet per degree and bending stiffness of 47,000 pounds per inch of deflection (both numbers exceed those of the GT).
Front and rear crash protection is provided by the Uni-Chassis, while the bodywork must bear the roof-crush, side-impact, and seatbelt loading. The driveshaft runs down the center of the tube, supported by three bearings (it needs no U-joints). The engine and transaxle are stressed members bolted directly to the chassis, so all sound and vibration isolation must come from the body mounts.
Want a longer or shorter wheelbase? Just trim the extruded tube to length. Want it lighter? Mandrel-wound carbon fiber trims some 30 pounds. Cheaper or smaller? A steel tube optimizes at about 6 inches in diameter. Looking to build an optimized EV not based on conventional architecture? Square off and enlarge the central tube and it’s a battery box. Weld hemispherical end caps to it and it’s a compressed natural gas tank (for a front-drive or rear-engine rear-drive setup).
Extrusions are inexpensive and sand-castings are affordable in low volumes, making this modular design cost effective for niche products—initial studies peg the investment cost at half that of the GT, with the tooling payoff at 1500 cars priced at $100,000. Using Corvette suspension components could lower the price even further. The Uni-Chassis has the makings of an ideal plug-’n’-play rolling platform for high-end niche products like the Cobra body shown hovering here. Then Theodore mentions that an Indian concern wondered aloud whether a bare-bones steel version could help put the Third World on wheels. Why not?
Frank Markus on May 13 2011 8:00 AM Tags : amc, asc, chris theodore, Chrysler, Ford, Ford GT, ford gt supercar, ford supercar, general motors, gm, gt supercar, lotus 33, sallen, technologue, uni-chassis, unichassis, unichassis powertrain, unichassis suspension
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