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.
It makes no difference if...
It makes no difference if you start at the front or rear of the car when installing the Kenny Brown suspension as long as you install the entire suspension. Stang-Aholics opted to begin at the rear, and here is the first step, removing the Third-link's upper mounting bolt, accessed under the rear seat in the passenger compartment.
It takes some fishing around...
It takes some fishing around to see the four mounting bolts holding the Third-link to the differential and chassis. Here, Ron Peter, Ryan's dad and major supporter (it comes with the job), guns off the fifth bolt, the one passing through the link and differential. Handling these bolts requires some muscle and hardware to gain access.
There's no way to get a camera...
There's no way to get a camera in where the Third-link lives, and in fact, the techs have a bit of a time seeing it themselves. Here the Kenny Brown link assembly is going it. It helps to have two folks, as one can pull down the gas tank a little while the other fishes the link into position.
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
Fitting the rear springs holds...
Fitting the rear springs holds no mysteries. Kenny Brown supplies an adjustable spring perch for the rather short Eibach rear coils, which gives some adjustability to the rear ride height, but count on about an inch of lowering.
Kenny Brown deletes the rear...
Kenny Brown deletes the rear sway bar at the Street Sport level, so the existing aftermarket bar was removed from Ryan's car. This is easy nut-and-bolt work.
Likewise, fitting the new...
Likewise, fitting the new H&R rear shocks is easy wrench work as well. With the car on a lift, you have the choice of either lowering the car or using a ladder to access the trunk and the upper shock nuts. The non-adjustable Street Sport shocks means they are ready to go out of the box.
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.
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
Kenny Brown lowers and straightens...
Kenny Brown lowers and straightens the rear lower control arms via new brackets. The bolt being tightening here requires a new hole drilled through the KB and stock brackets. This gives two bolts per bracket--the second bolt is hiding behind the wrench in this photo--so the bracket can't pivot.
Installing the new lower control...
Installing the new lower control arms is easy once the new brackets are in place. The arm’s length should be set to mimic the Ford arms that were removed; here Ron is double-checking that nothing moved during installation.
After removing the stock Panhard...
After removing the stock Panhard bar and its reinforcing strut, the beefier Kenny Brown strut is substituted in its place. Once this brace is fitted, new brackets are slipped into the stock brackets.
With the Kenny Brown Panhard...
With the Kenny Brown Panhard rod brackets in place, both sides are drilled, with one hole for a locating bolt. Note how the bracket has two holes for the Panhard bar, which provide some adjustability of the rear roll center.
With the two KB Panhard rod...
With the two KB Panhard rod brackets drilled and bolted to the stock brackets, the Panhard bar itself can finally be installed. Again, the bar should be the same length as the stock bar to begin with. Expect to have to push some to get the Panhard bar to line up with its mounting holes as the suspension swings sideways a bit at full droop when the stock bar is removed.
Step one in fitting the subframe...
Step one in fitting the subframe connectors is to temporarily clamp the straight bar to the jacking rail, then hold up the truss portion. The legs on the truss are purposely too long to accommodate chassis variations, so mark the truss for a snug fit to the jacking rail reinforcement, fire up the whiz wheel, and trim the truss to fit.