Tom Wilson
October 26, 2012

To hit the high points, the Street Sport kit uses weld-in subframe connectors, and new control arms on the front and rear suspension. The subframes come out of the box in two pieces and are trimmed to fit the chassis, tack-welded together in place, fully welded on the bench, and then the assemblies are welded to the chassis. The rear suspension is a pure bolt-in affair, replacing the Third-link above the differential (requires partially lowering the gas tank and accessing under the rear seat), plus the two lower control arms. A new Panhard bar is installed, along with relocated pickup brackets.

In front, the lower control arms are replaced and one of the attach point holes enlarged--there's some blacksmithing involved here as welded-on captive nuts must be chiseled off. The springs and shocks are replaced all around, of course. There is no rear sway bar--Kenny says he has the rear roll center so low that a rear bar is not needed in the Street Sport kit--and Ryan already had an adjustable front sway bar on his car, which was deemed correct for the application by Kenny, so it was left in place.

A few weeks after the install, we met with Stang-Aholics and Kenny Brown at Buttonwillow Raceway Park. This was our first look at the Kenny Brown Gen-IV parts in action and we were impressed. Ryan's car was purposely set up in street trim, with less spring and shock rate than optimum for hardcore track duty but with an easy street ride for daily driver duty. This is how most street cars are set up--and should be set up--and it's also the most forgiving for the neophyte track driver.

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Nevertheless, the Kenny Brown augmented chassis proved friendly, with excellent stability, a surprisingly sharp turn-in, some understeer at mid-corner, and enthusiastic grip for hard acceleration on corner exit. There was good precision throughout the lap, and always a sense of confidence and predictability--traits rewarding to the beginner and accomplished track pilot alike.

The newer and less aggressive drivers on hand were well-served and happy with the street spring and shock settings, while the hard chargers only needed a smooth touch to extract good speed from the combination. The plush action of Ryan's car didn't surprise us, as Kenny Brown has traditionally gone for compliance over resistance in his suspension tuning. (The deleted rear sway bar is a good example).

All suspension tunes have a limit, and as is proper, the limit with Ryan's car was understeer, felt mainly in the high-speed sweepers. In the big open turns, the front tires gave up first and you had a choice of forcing the issue with the throttle--which would quickly over-heat the front tires--or show a little patience and maintain a lighter throttle, letting the big, heavy street car arc through. That said, the basic balance of the chassis was good, so fiddling with the spring/shock tune, or definitely a small rear swaybar, would trim the understeer out. In other words, the GT-4 suspension worked as advertised: smooth on the street, grippy to the spring/shock limit at the track, and ready to respond to more aggressive tuning should the owner opt for it. 5.0

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Horse Sense: Yes, Kenny Brown the car builder is Paul Brown, father of the World Challenge champion. Interestingly, the Browns each forged their own way in motorsport with near total independence from the other, although they collaborate when possible.

Suspension Heritage

Kenny Brown can trace his current Mustang offerings through four levels of development. Here's how they break down:

  • '87-'92 AGS Gen I (Saleen-R & Fox Mustang)--Revised front K-member geometry
  • '93-'00 AGS Gen II (Fox Mustang, SN-95 Mustang)--Fixed-strut front geometry, TracKit plus rear geometry
  • '01-'04 AGS Gen III (SN-95 Mustang)--AGS tubular K-member and control arms, AGS rear IRS module
  • '08 AGS Gen-IV (S197 Mustang)--AGS tubular K-member and control arms, AGS Three-link live axle rear geometry

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