Matt Rawlins
March 1, 2000
Contributers: Matt Rawlins

Step By Step

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Here’s the ’99 Cobra just before it entered the shop for its suspension makeover. The price for this suspension kit is still undetermined as of this writing, but it is expected to sell for about $1,400-$1,500.
Here’s the complete Kenny Brown suspension kit which includes a set of double-adjustable Koni Yellow dampers, Kenny Brown variable-rate coil springs, Hotchkis Delta caster/camber plates with strut boots, and Kenny Brown’s Extreme Matrix subframe connectors with jacking rails.
Note the wimpy factory subs that were on the Cobra on the right. Can you say, sub-flex-a-lot?
The first step was to remove the factory subframe connectors which come only on convertible Cobras. These connectors, made from mild steel, are a lot weaker than Kenny Brown’s heavy-duty units. Just swapping out the subframes should make a huge difference in the chassis’ stiffness.
Phil Gizzi begins by removing the rear wheels to access the independent rear suspension.
Removing the rear spring coils can be dangerous and difficult. Here, it took the work of two people and the use of a crowbar. The crowbar is actually one of the only tools that is perfect for dislodging coil springs. The end of the crowbar slides underneath the coil and the perch it sits on. With a mighty arm, the coil should, ideally, pop out gently. We don’t recommend trying this maneuver at home, however.
Once the coil spring was removed from the passenger side we measured it up next to the Kenny Brown rear spring—what a difference.
Once both springs were installed, it was time to swap out the rear shocks. Unlike the Fox-bodied Mustangs where all you had to do was lift the hatch area and pop out the round plastic shock cover to access the location, the newer SN-95s, as with this ’99 Cobra, require you to access the shocks via the trunk area. To do so, you first need to remove the lining in the trunk.
When the shocks are being installed, don’t forget to also install the special washer that comes with the kit. The washer is placed between the shock and the lower arm of the IRS. The other side of the rearend can now be done exactly the same way. Reinstall the trunk lining and zip it all up.
With the rear finished, the front can be lifted and the front suspension supported by a floorjack in order to remove the coil springs. Again it’s important to be extra careful when dealing with springs.
Check out the difference between the stock (left) and Kenny Brown coil.
Since we are installing a set of Hotchkis caster/camber plates in the Cobra, we need to remove the old plates first and then put the new ones in along with the new Koni struts. Removing the old plates is just a matter of loosening up a few bolts and chipping off the old metal tabs on the strut tower.
The new Hotchkis plates are a definite must when you’re spending this amount of money on your suspension. It would be a real crime not to arm your front suspension with some sort of aftermarket caster/camber plates which increase suspension travel (horizontally) and allow you to fine tune the tire position in relation to the pavement.
Don’t forget to install these offset steering rack bushings which are included with the kit. Their job is to keep the steering geometry the same as stock, or as close as possible to the way it was before. Whenever you lower a vehicle with tighter, shorter springs, the steering geometry will change as well, unless you include the bushings or adjustable tie-rod ends which alleviate the difference.
The strut tower brace plays a big role in the front suspension. By triangulating the front of the car, the steering input feel is increased by creating a juncture of three points, two on either side of the strut towers and one along the firewall.
The Extreme Matrix subframe connectors can now be added to the mix. They don’t necessarily have to be done last, but since they take a little longer to do we saved them for last. First, the actual Super Subs are bolted on where the factory subs were, then the jacking rails are welded in along the side. Once those two pieces are secured, the middle section (looks like a wide M) of the extreme matrix subframes can be wedged in between. But before the middle section can fit, it must be measured and cut as necessary.
The cutting can be done in about 20 seconds with a cutting wheel like the one used here—one reason why you should have a professional shop install these subs.
With everything fitting snugly, Phil puts on his welding outfit and mask and goes to work. He makes sure to weld at all critical joints and points where the pieces meet and stress will be added.
After about 10 minutes of welding, the final product is a masterpiece. Although this photo shows the bare metal color of the sub system, GRC painted it black with some engine paint in order to keep rust out and let it blend in with the rest of the underpinnings. The owner off this ’99 Cobra will definitely be pleased with the stiffer chassis.
After all is said and done, the guys took the Cobra out for a test run on the street to see if the rear wheel hop was in fact eliminated. Happy faces and wide grins told the story. No more bunny jumping and unwanted flex for this ’99 snake.

If you happen to be one of the many new, unhappy owners of a ’99 Mustang Cobra, chances are you have been, or will be, experiencing two negative reactions with the car. This isn’t a ’99 Cobra-bashing story, but rather a Cobra-aiding story. So don’t write us letters saying we here at 5.0 hate the new IRS Cobra, because we don’t. It has a great new look and tons more sophistication than any other Mustang in the past.

There are, however, some problems—the two most obvious being the lack of advertised power (which is being addressed by Ford and should be under control by the time this hits the newsstand), and the car’s rear-wheel-hop problem. If you’ve driven an independent-rear-suspension vehicle before and driven it fast off from a dead start, chances are you’ve experienced wheel hop. Basically, it’s the act of the rear wheels rapidly bouncing up and down on the pavement like a basketball.

This is bad for a few reasons. For one, it doesn’t create a smooth and comfortable ride for you or your passengers. Granted, wheel hop, at least with the ’99 Cobras, doesn’t happen just in any type of daily driving, but even so, it shouldn’t be happening at all. The biggest complaint has been that the rear tires hop like a rabbit during a launch no matter how low or high the rpm. Apart from being uncomfortable, wheel hop also keeps the tires from being able to firmly plant themselves to the pavement. For all you weekend warriors who like to go to the dragstrip, this isn’t a good thing. Traction rules at the strip, and without traction your e.t.’s go higher than a hot-air balloon in hell.

We know the IRS Cobra was designed more for cornering than it was for the dragstrip, but it would be nice to have a car that can corner beautifully and still keep most of its tire tread on the asphalt during a launch. If Japanese and European sports cars can do it, then so should ours. Thankfully we have aftermarket companies like Kenny Brown Performance who take on challenges such as this to create a system that will benefit all.

According to Kenny Brown Performance, its new suspension kit for the ’99 Cobra will drastically reduce wheel hop. This is accomplished by creating a much stiffer chassis with the subframe connectors and control the wheel hop with their coil springs and double-adjustable shocks in the rear (which already come correctly valved from Kenny Brown).

To get the inside story on the Kenny Brown fix, we went to GRC Performance in Mission Viejo, California. There, Phil and Umberto Gizzi— owners of the shop—tackled this project head on. Follow along as we show you how to get your ’99 Cobra stiff and stable.