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2007 Ford Shelby GT500 Convertible
Serious fun.

By Matt Delorenzo • Photos by Jim Fets
ROAD & TRACK



The look of the Shelby GT500 is purposeful, almost menacing in a way. The nose is bluff, taller because of a domed aluminum hood that shields a 5.4-liter V-8 topped by a supercharger. To help move air through the engine compartment, the grille and lower intakes are larger and there are additional extractors in the hood surface. The maw looks even more gaping since the standard Mustang pony has galloped off to parts unknown, replaced by a coiled serpent that now nests off to the side.

A new chin splitter accentuates the Mustang's shark-nose look, and that aero aid is complemented by a rear diffuser and deck spoiler. Pull two latches and push a button, and the three-layer canvas roof retracts. It's time to get down to business.

Highly bolstered sport seats with a retro stitch pattern and Cobra logos fit like a glove. A leather-clad steering wheel with convenient thumb grips also sports a snake on its hub. The instrument panel is stock Mustang, and yet something's different-the tach is now on the right, closer to the shifter. The graphite faces with white lettering have a small SVT logo, which tips you off to the car's pedigree. That logo is a programmable shift light, another thoughtful touch to go along with the aluminum-accented pedals and gearchange.



Twist the key and the 5.4-liter V-8 rumbles to life, sending its bass notes down a 2.5-in. exhaust that features an X-pipe and dual tips. Goose the throttle and an Eaton M122 supercharger (upgraded from the previous-generation Cobra's M112 blower) pumps 10 to 12 psi into the combustion chambers. Seated next to me is Jay O'Connell, chief technical engineer of SVT, who says coyly that both horsepower and torque are somewhere between 470 and 480, though final numbers are still pending. For argument's sake, we'll say 475 bhp and 475 lb.-ft. of torque.

Depressing the clutch takes no more effort than on a stock 300-bhp 4.6-liter V-8 Mustang GT. That's because instead of a single plate, the Shelby GT500 has a dual-disc clutch coated with a cerametallic coating. Each disc is only 215 mm in diameter, as opposed to the stock 240 mm, and two of them offer much more surface area and less inertia, allowing the engine to spin up freely. "The cerametallic material is like racing brakes versus base brakes. The material can hang on for much higher temperatures and stand a lot more abuse," O'Connell explains.



I dump the clutch to prove his point. With traction control off, the rear 18-in. P285/40 Goodyear F1 Supercar tires light up, the car steps out slightly but quickly comes back in line while the free-revving engine hammers off the rev limiter. O'Connell smiles and notes that the wider rear tires (compared with the P255/45 radials up front) help keep the rear end in check.



The Tremec 6-speed, with its beefed-up gears, triple synchros in 1st and 2nd, and high multiplication in 1st thanks to a 2.97:1 instead of a 2.66:1 ratio, provides quick, snappy shifts. This is the same gearbox found in the Dodge Viper, but thanks to some changes in the linkage, it feels less balky and much more precise in action. The 3-4 upshift still takes slightly more effort to snick positively into place, but overall, the gearbox's action is intuitive.

After the scorching burnout, we roar up a steep incline on Ford's Hill Course at its Romeo, Michigan, proving ground. Under full throttle, the throbbing exhaust pulses compete with the whine of the supercharger. While not as raucous as the blower on the previous-generation Cobra, there's no doubt that the GT500 is operating under forced induction. Roll out of the throttle, watch the boost gauge drop to zero and the noise all but disappears. Motor around at lower speeds, and the extra boost noise is barely noticeable.



While the GT500 is similar in concept to the hairy GT500KRs of yore, its execution is decidedly civilized. The first impression is that of a tractable, easy-to-drive sporty car with linear power delivery at lower speeds. That linear feel masks the beast beneath-the GT500 is ready to rock when you jump on the accelerator.

Even though the iron-block Triton V-8 and its peripherals including supercharger, intercooler and beefed-up transmission add nearly 300 lb. to the curb weight (much of it on the nose), the GT500 feels remarkably balanced, almost lithe. True, the convertible loses some structural rigidity, but the blow is softened by its improved weight distribution. The coupe, which tips the scales at less than 3900 lb., is about 150 lb. lighter than the convertible, the extra weight attributed to the top mechanism. At just over 4000 lb., the convertible carries this extra mass mostly behind the driver.

In addition to being slightly less nose-heavy than the coupe, the convertible is slightly softer in springing and damping. This not only improves ride, but also compensates for the lack of stiffness inherent with a convertible. Still, O'Connell says that body engineers have gone through the structure and shored up several joints and seams to compensate for the extra weight of the powertrain. These improvements have been incorporated in the base coupe and convertible, making all Mustangs better as a result of the development of the GT500. In addition to those body improvements, the GT500 sports a strut-tower brace that ties both sides of the engine compartment together.



These improvements contribute greatly to the solid feel of the convertible. There's no cowl shake, shimmy or rattles usually associated with an open-top vehicle. The convertible feels a little more fluid than the coupe, but even over tar strips and other road imperfections, the body is solid.

With slightly more effort needed than in the stock GT, the steering is accurate and nicely weighted, although off-center feel could be a bit crisper. O'Connell said additional tuning will sharpen that response by launch. Needing no extra work is the braking. Larger 14.0-in. front discs are clamped by 4-piston Brembo calipers, while 2-piston calipers work on the rear 12.4-in. discs. The brake pedal feel is positive, with firm feedback making it a breeze to modulate the stopping power.

The overall driving experience of the GT500 is pleasant in normal driving and exhilarating when you're on it. The handling is fairly neutral until the massive power is tapped to induce power oversteer. Lift the throttle and the back end settles into place. The predictable nature of the suspension is owed to its simplicity. While the previous Cobra had an independent rear, SVT decided to work with the car's stock live axle setup, refining it to match the characteristics of the car. O'Connell said a modular approach to an independent rear (on the previous car, the independent rear bolted into the same space as the stock axle) would have added weight, cost and still would not have had the optimum geometry because of the packaging constraints. The GT500 is no Ford GT, but it doesn't try to be. And buyers who will be looking to race the car will find that upgrades to the live-axle rear setup will be easy and inexpensive.



There's that word, inexpensive, which is really the charm of the GT500. Although pricing has not been set, word is that the coupe will start at around $40,000, with the convertible costing approximately $4000 more. There's not much out there that offers this kind of performance for so relatively little money. Ford is banking on it and hopes to find 10,000 buyers a year starting June 6. Serious business, indeed.

Ford Shelby GT500 Convertible


List price est $44,000
Curb weight est 4000 lb
Wheelbase 107.1 in.
Track, f/r 62.8 in./63.0 in.
Length 187.6 in.
Width 73.9 in.
Height 54.5 in.
Fuel capacity 16.0 gal.
Engine & Drivetrain
Engine type superchrgd dohc 4-valve/cyl V-8
Displacement 5409 cc
Bore x stroke 90.2 mm x 105.8 mm
Compression ratio 8.4:1
Horsepower (SAE) est 475 bhp @ 6000 rpm
Torque est 475 lb-ft @ 3500 rpm
Fuel delivery elect. sequential port
Transmission 6-speed manual
Chassis & Body
Layout front engine/rear drive
Brake system discs/discs
Steering rack & pinion, pwr assist
Suspension, f/r modified MacPherson struts, coil springs, tube shocks, anti-roll bar/live axle, 3-link, Panhard rod, coil springs, tube shocks
Wheels aluminum alloy, 18 x 9 in.
Tires Goodyear F1 Supercar; 255/45-18 f, 285/40-18 r
Performance Claims
0–60 mph 4.5 sec
0–1320 ft (1/4 mile) 12.9 sec
Top speed
(electronically limited) 155 mph


5 Questions with Carroll Shelby



R&T: What is your involvement with the Shelby GT500 program?

Shelby: That's hard to decipher. It's got my name on it. I got talking to John Coletti and Edsel Ford about the Ford GT, and then got talking about what a Mustang should be. We just sat around and brainstormed. Time has passed for old hot-rodders like me who just went out and built cars. Now you have all these young hot-rodders, like [SVT Director] Hau Thai-Tang and [SVT Chief Technical Engineer] Jay O'Connell, who can build it for you. All I look at is setting objectives for what you want the car to be. And, of course, I drive it and give them a few suggestions. I'm really high on Hau and Jay. They have made something that will be very desirable for the price.

R&T: Besides the open top, is there anything different dynamically in the convertible versus the coupe?

Shelby: It's 150 pounds heavier on the rear end; you can feel that when you start approaching the limits. It helps the weight balance a little bit, and it starts oversteering earlier. That doesn't make a difference to the average guy. Because of the extra weight, it will be a little slower on acceleration. I like the coupe better for handling, but I also love the convertible; it will stay tight a lot longer. No one has built a convertible with this kind of performance for the dollar.

R&T: Some feel the car should have an independent rear suspension, like the previous-generation Mustang Cobra — what do you think?

Shelby: That's bull. We proved a long time ago that for ordinary driving and going around a skidpad with a straight rear axle, you can do it as well as you can with an independent rear. It takes a lot of engineering, weight and cost to do an independent suspension. By not doing it, we took $5000 out of the car.

R&T: What do you see as the competition for the GT500?

Shelby: For horsepower, performance and price, I don't see anything out there. It will be like the Mustang comes out and in four years there might be a Camaro or something. Still, I don't know anywhere you can get nearly 500 honest horsepower with four seats. I think it's way ahead of the competition.

R&T: Is there room in the Ford line for a sports car positioned between the Mustang and GT?

Shelby: Yes, but I see with all the financial problems, it will be probably be built outside the company. I like the Shelby GR-1 concept we did. I would like for Ford to do that, but with the problems they have it's not likely to happen any time soon. Still, I have a few concepts I'm pushing with them.
 
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