Stiffer is Better
Chassis alterations include 7 percent stiffer front springs, 13 percent stiffer rear springs, a smaller front anti-roll bar, and dampers with significantly tighter rebound control. In addition, the wheel size is larger at 9.5 x 19 inches to support Goodyear Eagle F1 Supercar tires providing a bit more grip with a more resilient ride. Conscientious tuning has yielded a car that doesn't beat you up over poor surfaces combined with stringent body motion control.
The live rear axle located by three trailing and one lateral (Panhard rod) links lives on in this uber Mustang. Crossing truly evil corner bumps, the un-sprung axle's momentum is a major handicap, but for most driving situations, there's no hardship involved with the rudimentary suspension system.
We measured a nicely balanced 0.97g stick in left turns and 0.96g in right turns. At the adhesion limit, the front tires chatter noisily wide of the line as the car's tail tracks obediently. With the stability control disabled, booting the rear tires loose to explore the drift zone is no challenge.
The recalibrated gas-pressure dampers do a nice job of managing pitch and roll motion except during hard braking and full-tilt acceleration. Also, during rapid left-right race track transitions, the GT500 exhibits a slightly top-heavy feeling.
Unfortunately, there is one circumstance where the GT500 trips. If excessive rpm is used during a drag-style launch from rest, the rear axle enters jack-hammer mode with violent hopping and intermittent rubber-to-road contact. The new axle ratio and added torque combo doesn't work as well as the 2006-2008 arrangement. That's an odd situation for a car that has such a devout straight-line, quarter-mile following. During recent tests of the new Camaro with an independent rear suspension--supposedly ill suited for drag use--we observed no such traction problem. To circumvent the axle tramp issue, the GT500's electronic stability system has a launch mode that automatically modulates the engine's throttle. It works as advertised.
Pinks Can Wait
What you really want to know is whether the GT500 puts the hurt on its obvious rivals - Camaro SS and Challenger SRT8. There's no doubt it wins the power to weight ratio calculation. While we have conducted a first round of acceleration tests, the results are so far inconclusive due to adverse weather and traction circumstances.
This much we can say with confidence: Stopping performance provided by four-piston Brembo calipers in front and ordinary sliding calipers in back is significantly improved. Cornering grip is not only higher but significantly better than both the Camaro and the Challenger. What the GT500 lacks in suspension sophistication, it more than makes up with well chosen chassis calibrations.
The acceleration we've measured so far spots the new GT500 right on top of both its predecessor and the new Camaro SS, but quicker than the Challenger SRT8. The run to 60 mph took 4.9 seconds on the way to a 13.3-second, 112-mph quarter-mile. That's disappointing for the hottest cannon in Ford's 2010 arsenal but surely not a final answer on this subject. As soon as the sun shines on a retest of the Shelby GT500, we'll update the record with more legitimate acceleration figures.