Pete Epple Technical Editor
April 5, 2010
Photos By: Marc Christ, Justin Cesler

As an associate editor of what I feel is the greatest car magazine available today, I am afforded the luxury to go racing on an almost weekly basis. Even though parts are swapped constantly and testing happens all the time, track and weather conditions can change greatly between test sessions, making inconsistent results.

At a recent editorial meeting, I threw out the idea to install a street/strip suspension and test it. Although we've done this before, this would be a track-side install. Even though I made much more work for myself, being able to perform a true A/B test with little variation in conditions was something I really wanted to try out. Over the past few months, we've made a few upgrades to Blow-By Racing's (BBR) '10 Mustang GT. With horsepower numbers well above stock, this Pony would be the perfect candidate for our trackside suspension swap.

Once our track day was set, the MM&FF staff sat down with the crew from BBR to layout our plan of attack. We wanted to add components that would give this Stang the flexibility to get all of the newfound power to the track efficiently, yet be comfortable enough to serve as daily transportation

Being that our test Pony has already produced respectable numbers on the strip with a completely stock suspension, it was time to see if further improvements could be made. BMR Suspension (Thonotosassa, Florida) manufactures and sells a full line of suspension components for the S197 that are designed for extreme street performance. When the decision was made to upgrade the Stang's suspension, BMR was a perfect fit.

"When you start throwing suspension parts at a basically stock Mustang, it doesn't always make you faster," explains Lee Spicher of BMR Suspension. "The improvements we (BMR) make will greatly raise consistency. The adjustability of BMR's suspension components also allow for a much more aggressive suspension setup than the stock parts." This is especially important for poor track or street conditions.

Prior to hitting the strip, the crew at BBR installed a few components that couldn't be done easily at the track. BMR's boxed subframe connectors will add all of the rigidity this Pony will ever need, but welding them in is not something easily done on jackstands in the pits.

BMR's adjustable upper control arm and mount were also installed prior to our track day. The adjustable piece is made of 15/8-inch tubing, with 0.120-inch-wall thickness, which is much stronger than the stock stamped-steel link used from the factory. BMR's upper control arm mount allows us to raise or lower the third-link mounting point to fine-tune the rear suspension geometry.

At The Track
Our day started with the '10 GT in stock trim and the stock 19-inch wheels on all four corners. The combination of a cold track (45 degrees in the morning) and stock street tires is not a recipe for traction. With a very mild launch and easy shifts, the GT spun its way to a best baseline run of 13.63 at just over 106 mph, with a 60-foot time of 2.28 seconds.

As we watched the car dance through Second gear for the first three runs (read massive spin), we hoped for a big improvement with better rolling stock. We swapped the stocks wheels and tires for a set of "big and littles" from Race Star Industries. The polished DragStars checked in at 15x3.75 up front and were wrapped in 26x4.5 Moroso DS2 rubber, with 15x8s in the rear using 275/50-15 Mickey Thompson ET Street Radials to claw at the track.

After a healthy burnout to bring the drag radials up to temperature, our test pilot was able to get much more aggressive on the launch. The benefit of sticky meats was apparent right from the hit, as the Pony bogged on the first launch, running a 13.91-second pass at 107 mph. With the launch rpm adjusted, the next passed yielded a much-improved 2.04-second 60-foot time, which lead to a 13.10-second timeslip at over 108 mph. The backup pass netted us a quicker 12.82-second e.t. at a similar 108 mph. Then it was time to tear down.

With the '10 resting comfortably on the tallest jackstands we could find, Chris Jones of BBR went to work unbolting the rear suspension. The first pieces to go were the stock lower control arms.

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After the stock stamped-steel arms were removed, we bolted in the relocation brackets from BMR. BMR's lower control arm relocation brackets lower the mounting point of the control arm either 1 or 2 inches at the rear housing. Lowering the control arm mounting point on the rearend alters the vehicle's instant center. If you draw an imaginary line through the mounting points on the body and rearend for both the lower and upper control arms, the point where these lines intersect is the imaginary instant center. Knowing where the instant center lies helps determines how quickly or aggressively the rear suspension will react on launch (and during braking), so it's a great way to control how hard a car will plant the tires. The shorter and higher the instant center intersection point, the faster and harder the car will plant the rear tires. The downside to this is the tire can also unload faster if it doesn't stay hooked.

Next we installed Blow-By Racing's billet lower control arms. These lightweight arms fortify the rear suspension and won't have as much deflection as the stock stamped-steel arms. We chose to install the control arms in the lowest position in the relocation bracket. This raised and shortened our instant center.

The Panhard bar is responsible for locating the rearend under the car from side to side. Because it's now too long, the stock Panhard bar pushes the rearend housing to the left side of the car as it's lowered. BMR's adjustable Panhard bar allows you to shorten the Panhard bar to keep the rearend centered under the car. We also added BMR's upper Panhard bar support brace for extra strength.

To complete the rear suspension, we swapped the rear shocks. Strange Engineering sent us a set of double-adjustable dampers, which offer the ability to independently adjust compression and rebound. This gave us all the tuneability needed to get down the track.

As Jones moved his attention to the front suspension, the stock struts and springs were unbolted. Strange Engineering is in the process of engineering brand-new coilover struts for the S197, so we helped with the R&D. The single-adjustable struts bolt into the stock location and use a 2.5-inch-diameter, 14-inch-tall, 200-pound specific-rate spring to support the front end.

The prototype Strange struts don't have provisions for the swaybar, so the swaybar had to go. BMR's radiator support brace does away with the stock swaybar anyway, and replaces the bulky factory support brace. The brace also helps take some weight off the nose. With the sway bar and factory brace removed, the BMR piece reduces nose weight by over 26 pounds. After setting ride height, we were ready to hit the strip again.

Before rolling into the burnout box, we took a few minutes to set tire pressures and adjust the shocks and struts. The rear double-adjustable shocks offer 10 settings for each adjustment. For our baseline, we set both the compression and rebound on the fifth setting. This gives the rear shocks a neutral starting point so we can gauge what adjustments are needed.

After tire pressures were set to 18 psi, the rear was ready to go. The front struts were set to full loose for the first pass, and we rolled to the line.

As the lights went green and the clutch came out, the rear squatted but there was considerably less movement (read lift) in the front end. Even though there was some wheelspin at the hit, the 1.96-second 60-foot time was marginally better than our earlier runs, and the 12.79-second e.t. was a step in the right direction.

After stiffening the compression and rebound by one setting on the rear shocks, we headed out again. With the launch technique altered a bit for the new suspension-taking the clutch out at 4,000 rpm as opposed to the 4,800 on the previous pass-our '10 GT launched hard to a best 60-foot time of 1.80 seconds and a best e.t. of 12.56 at almost 110 mph.

It was a great experience to help Strange Engineering with the R&D process for the new S197 coilovers. Being that we've worked with Strange many times before, we hoped the new coilovers would work right out of the box, but the valving in the struts was way stiffer than we would have liked.

"The S197 Mustangs are much heavier than the Fox chassis or SN-95 Mustangs, so the valving needs to be stiffer," explained JC Cascio, sales manager for Strange Engineering. "As the R&D process goes on and we get feedback, we can make changes before releasing the final product."

With our test coilovers back at Strange, we'll do more testing after some revalving. Check us out online at www.musclemustangfastfords.com for more test results with BBR's '10 Mustang GT.

All in all, it was a successful day at the track. After a few hours of work and a healthy amount of passes, we lowered our e.t.'s by over a second and picked up over 5 mph. Not bad for a day at the track!

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