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1958 Chevrolet Corvette - Treasure Coves

Mining A Vintage Platform For Performance Gold

Christopher R. Phillip Nov 1, 2008
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Enjoying a '58 Corvette has always been about the beauty of the car's sirenic exterior, which serves as a welcome antidote to the pitfalls of its premodern engineering. But while some Vette owners deliberately cleave to the C1's original blueprint, others are willing to make concessions against originality to create a Corvette that is as pleasing to drive as it is to behold.

Carey McMahon, managing director of an engineering and technology company in Wahroonga, Australia, tells VETTE he wanted a '58 Corvette but was shocked at how poorly a stock example performed. "One day I saw a '58 advertised, so I went over to check it out," he says. "It looked like sex on wheels sitting in the guy's driveway. Then I took it for a test drive and got such a disappointment. It drove like a truck-a '50s truck. Driving special cars just warms my core, but this car left me cool as ice."

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As fate would have it, McMahon's search for the perfect Vette led to a different '58 model. "I went to Portland, Oregon, to buy a '67 Mustang GT500," he says. "After I bought it, the seller told me about his next-door neighbor's '58 Vette. He took me over to meet him, and I offered to buy it. Two months later, he told me to come and get it."

According to McMahon, the garage-banished '58 roadster had left the factory painted in Regal Turquoise with white coves and a Charcoal interior. But when he found it, the body was sandblasted back to fiberglass, and the front clip was completely missing. He immediately thought of a comment he made to himself following his inaugural ride in a C1 some months earlier: "Wouldn't it be great if a '58 Corvette drove like a new one?"

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Fortunately for McMahon, Paul Newman of Newman Car Creations in Paso Robles, California, had shared the same thought and gone so far as to develop a solution. He explains: "McMahon's complaints about C1 Corvettes were similar to so many others: lack of control, poor ride, brakes not suitable for today's traffic, and engine overheating. Our advice to him was to have us engineer a complete C4 Corvette suspension to his '58 frame. Forged-aluminum, independent front and rear suspensions with power rack-and-pinion; modern, lightweight composite springs; sway bars; performance shocks; and disc brakes will stand a classic Corvette on its nose."

McMahon was sold on the idea, and in mid-2002 he delivered the chassis to Newman for modernization. The project consisted of stripping the frame of its original components and modifying it for a rebuild utilizing C4 parts. Newman suggested a custom fiberglass spring from Vette Brakes & Products, Bilstein shocks with a custom valve rate, and a '96 Corvette steering system for the front. For the rear, he prescribed a VBP transverse spring, another pair of custom Bilsteins, and a Dana 44 differential with 3.42 gears. Polyurethane bushings would be used throughout.

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The Corvette's original drums were deemed unacceptable for providing modern braking power, so front '04 Z06 calipers, rear '96 C4 calipers, and Disc Brakes of Australia (DBA) 4000 slotted rotors at all four hubs were selected to take their place.

Whereas most customers would have allowed Newman to install the components, McMahon wanted to handle the reassembly himself. In September 2002, using the modified frame, suspension components, body shell, and a freshly sourced front clip, he loosely assembled the Vette and shipped it to Australia. Upon its arrival, he embarked upon what would become a 4,000-hour restoration to turn his '58 Corvette into a modern-driving rocket.

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Working with George Athan of Mirrorfinish in Moorebank, McMahon designed and implemented the chrome and polished metal that can be seen under the hood and on the suspension components, driveshaft, and differential. "Athan and I worked together on most of the aluminum and steel items," he says. "I would do the rough work, and he would finish it off."

Next, he commissioned Chad Parrish of Mustangs R Us in Castle Hill to restore the body to its original beauty. Parrish labored 500 hours on the Vette's fiberglass panels, straightening them to perfection and widening the rear quarters 35 mm on each side to allow for larger wheels. Upon McMahon's orders, he then sprayed the body in two new shades: black followed by silver for the coves.

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Creating a suitably stout Corvette required an engine significantly more aggressive than the 283ci SBC that powered the '58 when new. McMahon went with an LS6 assembled by Aussie engine builder Thornleigh Cylinder Head Service. Thornleigh preserved the stock block and crank but slipped in Eagle forged-steel H-beam connecting rods and a set of forged Diamond pistons. Bolted to the block are AFR 205cc Mongoose heads with 66cc combustion chambers, Yella Terra Stealth rockers with a 1.7 ratio, and Comp 918 springs. An MTI B1 cam moves the valvetrain steadily with 221/221-degree duration, 0.558/0.558-inch lift, and a 114-degree LSA. The compression ratio is 10.5:1.

Ignition is sourced from an LS-series coil-near-plug system feeding ACCEL 10mm wires and A/C plugs. A custom cold-air induction system and a ported GM throttle body route air into a stock LS6 intake. Exhaust gases are evacuated through mild steel, ceramic-coated headers with 1.75-inch primaries, 2.5-inch polished stainless-steel pipes, and Hi-line stainless mufflers.

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Back in the United States, Howell Engine Developments in Marine City, Michigan, reprogrammed the ECU to make the LS6 function properly in its new home. According to Howell's Troy Brown, "The most important piece of the puzzle was to make sure that the vehicle antitheft system was taken out. We then eliminated smog requirements, fuel-pressure sensors, rear O2 sensors, and any other nuisance codes within the computer. In addition, we reprogrammed the spark and fuel tables to accommodate the AFR heads and hotter cam installed in the motor."

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Dyno testing by Stillwater Automotive Services in Silverwater, Australia, showed the '58 to be worth 395 rwhp, more than twice the output of the original 283. When McMahon feels the urge to unleash his Vette's potential, a Hurst shifter easily slams the six forward gears of a Tremec T56 manual that is custom-mounted to the chassis. "The T56 is a perfect addition to the drivetrain, and I love how the Hurst chrome shaft and white gearshift ball look just like the original '58 Corvette," he says. Allowing the Vette to make good use of all its newfound power are 17-inch PS Engineering wheels shod in Z-rated Daytona whitewalls.

The '58's cabin is worthy of accolades, too. McKenzie's Motor Trimming of Fairfield, Australia, recovered the original thrones in red leather and added a custom steering wheel, red-and-silver door panels, A/C, cruise control, satellite navigation, aircraft seatbelts, a Custom Autosound stereo unit (made to look like a factory unit, natch), a six-disc CD changer in the deck, and a Sony 4-inch rear speaker.

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The toughest part of the interior was the gauge restoration, and for that task, McMahon again took on the challenge himself. "I made a new lens with kph rather than mph for the speedometer," he says. "Then I fitted an X-box that converts the speed pulse from the gearbox and drives a short mechanical cable that attaches to the back of the original speedo. For the tachometer, I used a VDO gauge in the original housing and the original fascia. I fitted a voltmeter inside the original amp gauge casing and made the front fascia appear like the original. The oil and temperature gauges are original."

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Final assembly was performed by the owner, with electrical, brake, and engine details worked out by Andy's Restorations of Taren Point. According to McMahon, the results are "fair dinkum" incredible. At the Australia Summernats 2007, the '58 took on 1,200 competitors and received both Top Convertible and Top 20 Finisher honors.

But this is one Vette owner who has not found car shows to be his true calling. The real prize for him is the satisfaction he receives from having created a unique masterpiece combining vintage style with modern engineering. "The reason I built this Corvette was because I wanted the intellectual and engineering challenge it presented," McMahon says. "I thoroughly enjoyed solving complex issues on how to make the parts fit this car, and I ended up with a Corvette that is a trophy in itself. Owning the car is great, but building it was the best treasure."



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