Ford fans admire the strike of a Cobra. Chevy guys? For a bare-knuckled street fight, there’s nothing more brutal than the Cheetah. It can make a Cobra look like a garden snake by comparison. Sure, the Shelby was fast, but back in the Sixties, the Cheetah lived up to its namesake as the quickest creature on land. Trouble was, it was also the wildest beast you’d ever imagine.
Improving on its DNA with a Modernized Chassis
The engine was set back so far (a full two feet behind the front axle), there was no room for a driveshaft between the tranny and the diff. The output shaft of the Muncie 4-speed bolted directly to the differential U-Joint. That put the weight bias on the rear wheels, an oddity for a front-engine car. It also required running the exhaust headers on top of the foot boxes, and put the transmission right next to the driver, turning the cramped cockpit into a searing hot box.
Not only that, the “flexible flyer” frame made for unpredictable handling. The chassis acted like a giant undamped spring, flinging the Cheetah around like a jungle cat in pursuit of a scared rabbit. The car’s one saving grace was raw, unfettered speed—it could run down anything in its path, devouring the competition in a gulp. Speeds as high as 215 mph were possible on the high banks of Daytona (significantly faster than the 198 mph record that Dick Smith’s seriously modified Cobra roadster achieved.)
Given these quirks, it’s no surprise that Steve Chadwick would try to breed out some of the Cheetah’s more objectionable traits. But he knew not to tamper too much, having developed an abiding affection for the design since his first encounter with one back in the late Sixties. Even so, his physical stature was an issue (he’s 6’4” and tips the scales at 240 pounds).
Fortunately, there was some historical precedent in chopping the top to make more room, as the original Cro-Sal (named for Gene Crowe and Ralph Salyer) Cheetah was so configured. This quick fix also addressed the heat issue.
But what about that flimsy frame? Chadwick didn’t need a super-light racecar for competing against McClarens and Chaparrals, so he could improve on the breed without concerns about exact authenticity. He simply wanted to inject some sanity into an insane setup.
Chadwick addressed the foundation first, designing a center backbone that joins all four corners at the suspension pickups, forming a triangulated spaceframe. Taking things two steps further, he hard-mounted the aluminum engine block, so it serves as a structural component, and also added a perimeter frame for driver protection. Sure, there’s a weight penalty of several hundred pounds, but safety’s a legitimate concern here, and don’t forget that lighter aluminum engine provides an offset. And those Corvette C4 suspension components with Bilstein shocks and Hyperco coils require a stiff platform to function properly.
Chadwick took other liberties with the chassis, lengthening the wheelbase a few inches so that now a short, five-inch driveshaft would be required to link the trannie and diff. As a result, the front/rear weight bias is now 47 to 53 percent (instead of the original 40/60 setup). He also enlarged the rolling stock going to 10.5 inches up front and 12.5 inches in the rear (rather than six and seven inchers), and wrapped them with Hoosier rubber (275/40ZR17 and 335/35ZR35, respectively). Wilwood six-piston calipers on 13-inch rotors claw this feline to a clenching halt.
The change in rims altered the track width as well, so Chadwick fabricated larger fenders (not just flares) that flow with the lines of the original body. The dash is slightly wider as well, and he lengthened the hood a couple inches, and added a bulge for engine clearance. For a more predatory stance, he lowered the body slightly, and finished off the nose with a spoiler. To eliminate bumpsteer, he also installed a custom steering rack.
Getting back to that aluminum mill, it was built by Jim Horn of Exotic Engines with a Donovan block with Brodix heads, and runs a 12.6:1 compression ratio. Topped by four Dellorto carbs, it dyno’d at 533 horses, more than enough galloping steeds for a 2200-pound piece. Excess heat is vented by large custom louvers over the headers.
Thunder Ranch gave the car its finishing touches: fitment of the windshield, gauges, and dash, plus body prep and painting. Those final steps were critical, as Chadwick took home First-place honors in the Handcrafted Sports Car class at the prestigious 2011 Grand National Roadster Show. All of which means his Cheetah is no stray cat, but a purebred feline.
SOURCE: Thunder Ranch — (619) 444-1006 — www.thunderranch.com