Spec Mustang Turns Us Into Believers With Big Power & Great Handling

For the two hours before my first test session in a Spec Mustang, I lay in the bed of a rented truck trying to avoid the sun’s searing heat and catch a moment of shut- eye. Its reputation for being a bit brutal and the chance to drive it at the intimidating Sonoma Raceway made me much more excited than I’d been when testing the Spec E30 and the Spec Miata. Those cars rely on their nimbleness and cost-effectiveness. The Spec Mustang does not.

Well, for the stats it has, the Spec Mustang is reasonably inexpensive—and still probably within reach of racers of the aforementioned models. It’s fair to say the Mustang is just more in most departments; pricier, punchier, and porkier. It’s nearly 800 pounds heavier than a Spec E30, but I wasn’t worried. It’s also much more playful under power, and it has about twice the power of the BMW. As my friends would say, I was “super stoked.”

Spec Mustang

I was running on a few hours of sleep and the temperature was climbing to the expected high of 104 degrees Fahrenheit. I should have been regretting ever signing up for this, but I was still very excited

I had heard the Spec Mustang turn with an alarming urgency. According to those familiar with the car, with the right touch on the brakes, it changes direction shockingly quick. “Actually, all the others who’ve used this car have spun it in their first couple sessions. The funny thing is, it wasn’t on the power—they all spun it during turn-in,” says David Ray, founder of the racing class.

The Right Footwork

To make these cars turn, Ray hired CorteX Racing to build upon an already solid foundation. Most of the series’ current cars started their lives as school cars for Miller Motorsports Park. In that trim, they were fitted with Brembo F50 four-piston brakes and Tokico shocks and springs, rebranded Eibach sway bars, and an adjustable Panhard bar.

Filip Trojanek of CorteX developed a kit for the S197 chassis, though this was aimed mainly at HPDE driving. This used a set of true coilovers using single-adjustable Koni or JRi struts and rear shocks. This suspension provides a little more clearance than comparable suspension kits, so they capitalize on this by fitting larger wheels. Quickly, the formula for a V8-powered spec racer was underway.

Spec Mustang

The package includes large offset front struts, adjustable front anti-roll bar end links, bumpsteer kit, Watts Link, Stoptech brakes, Ford FR500 ABS module, slotted strut housing with CorteX camber slug kit, and a front swaybar. 

The package is pretty straightforward. The elements now mandated by the rulebook are large offset front struts for 18 x 10.5-inch oversized wheels and tires, adjustable front anti-roll bar end links, a bumpsteer kit, a Watts Link, Stoptech brakes, a Ford FR500 ABS module, a slotted strut housing with CorteX camber slug kit, and a front swaybar. Some choose to run a rear swaybar, but most don’t, as the car is willing to rotate with a simple rake adjustment. 

The Spec Mustang’s rotation is manageable, thanks to the benefits of the Watts Link. It compensates for the geometry changes as the rear’s links go through their range of motion. It also allows for adjustment of roll center.

“The loose handling characteristics are purely due to the driver’s preferences—it’s just the fast drivers have learned they are quickest when they set the car up as a momentum car (ie. loose) even though it isn’t that. If you take the rake out of the car and use the softer rear spring rate package, the car can actually understeer a lot. What’s great about the suspension is that it’s easily adjusted and can offer as much or as little oversteer as the driver feels comfortable with,” Trojanek elaborates.

Spec Mustang

A little oversteer, as we see here, is the quickest way around.

To study the changes made by this new kit, Ray and Trojanek took a pair of cars to Thunderhill Raceway in Northern California and tested them. Using AIM data loggers, they were able to compare the newly-upgraded car with one of the cars as they were run under Miller’s administration. The results were astonishing: nearly 2 seconds faster over a lap, and 10 percent better braking and cornering grip. Ray was sold and they brought on a few more interested parties.

Intentionally Little Adjustment

The range of adjustment is kept relatively narrow to keep the emphasis on driving. Two spring packages, two rear swaybars, an adjustable front bar, and tire pressures—that’s pretty much it. Even the gear ratios are factory. Fortunately, the motor’s torque offsets any gearing problems, moreso than a Spec E30’s engine can. That said, there have been some rule changes proposed recently to suit the Spec Mustang for use on longer tracks.

Compared to other Spec racers, the Spec Mustang holds a special tuning appeal. “These cars offer a little more adjustment than other comparable classes,” Trojanek says. “While a Spec Miata guy might prefer to just show up and drive, the typical Spec Mustang racer is a little happier to tinker on the car the weekend before the race.” 

That said, it’s not a vehicle for the engineering-obsessed. “You’ve got to remember, this is a Spec series, so you can’t really adjust too much. Thankfully, we found we could get the car to most drivers’ liking with only a few changes,” says Darrel Anderson, owner of American V8 Supercars.

“There’s no secret to getting these cars to work; you gotta’ drive them hard,” says Roger Eagleton, one of the fastest in the series.

“We found you have to give the car a good amount of ride height. This allows the suspension to do its work. Plus it keeps the nose from digging in under braking since rake is critical. Rake offsets the rear wing’s effect, which causes a little push at faster speeds, and generally helps rotation,” notes Ken Pedersen, Spec Mustang champion.

Fortunately, it’s not too challenging to get the car in its sweet spot. There’s not a lot of adjustment available and the accepted setups are fairly well-known. Still, there are some changes made for driver preference. Most of the front-runners opt for no sway bar at the rear. Some drivers opt for a slightly more neutral setup, but it’s fair to say that the fastest in the pack have learned how to live with a looser machine.

My Turn

When I got my turn inside, I was greeted with a spacious cabin with great visibility. As a bigger driver who feels cramped in a Miata, this is something I could get used to. It’s comfortable. Not just for its roominess, but for its ride quality and predictability. There’s a good amount of information coming through the wheel and seats. Honestly, the first few laps on a set of older Toyo R888s reminded me a little of rallycrossing, but at much higher speeds. 

Even with its tendency to spin the rear wheels, it wasn’t intimidating. It was fairly settled over crests, it was stable under braking, and the breakaway was, at least on those tires, never spiky. It’s just that it had a tendency to move around at the rear. I could always sense an impending slide. 

The funny thing about the Spec Mustang is that it gets you accustomed to sensations which might frighten you in other cars. A few laps in, while leaving Turn 6, I rolled on the throttle a little harder than I had up until then. The rear started to slide at a good 80 miles per hour, but it didn’t feel like an event. It was exhilarating, but not intimidating by any means.

The only thing which kept me from knowing the car better, aside from seat time, was a faulty ABS sensor that kept me from fully exploiting the brakes. I wasn’t able to experience the strength of the Stoptechs in the heavy braking zones, but I still got a sense of just how well the Spec Mustang belied its weight when trail-braked correctly. With the right rate of brake release into tighter corners, the Ford would yaw suddenly. It would happily point with little steering effort, and I could apply the throttle with much less hesitation. You expect that from a small car, but in something so large, it’s surprising.

Its pointier than its size suggests.

Truth be told, even if the brakes were functioning properly, I was still leaving a lot on the table in these all-too-brief sessions. Nevertheless, I was enjoying myself at 60-percent pace. Had I been driving a Miata or true momentum car, I probably wouldn’t have received the same adrenaline jolt, unless I’d been caning it everywhere and pushing braking points further. However, this Mustang had me chuckling contentedly with every slide at a relative trot. I was rolling on the throttle slowly, but every time I got to fully open the taps, that roar would flood the cabin and stretch a smile across my face. Plus, even at just over half-speed, I was kept pretty busy. 

Skills Conferred

And that’s why it’s such a step onward from a Spec Miata or E30. If the Miata forces its student to find mid-corner speeds and minimize scrub, the Mustang encourages the student to pick the perfect time to deploy the power with the right blend of propulsion and slip. When it does let go, there’s ample time to catch the slide. Since the car is always moving at the rear, it’s bound to teach its drivers how to do all the sideways stuff at a near-instinctive level in no time. 

Though some might think that all the power would make the racing boring, it doesn’t.

Thankfully, all that horsepower doesn’t ruin the wheel-to-wheel experience. Like the Spec Miata, the parity in equipment and emphasis on clean racing also force a driver to perfect their race craft.

“Once you get the hang of them, you learn that the cars are all evenly matched. It’s up to you to figure out how to race hard and clean. You have to typically pull off your passes under braking or in traffic, and we don’t condone leaning on other drivers. With a big car that has a tendency to move around a lot, you really have to get good at knowing how to position your car offensively or defensively without banging fenders or bumpers,” Eagleton elaborates.

Plans for A Populous, Cost-Effective Future

The power and the surprising friendliness of the platform may draw some, and the typical build cost of $30,000 probably isn’t out of reach for plenty of club racers. It seems the fear of greater consumable costs is what discourages a Miata or E30 driver from joining the SMG ranks. The series organizers are aware of this financial hurdle and have made strides toward finding a cheaper, more durable tire that still provides a reasonable amount of stick.

As for the other consumables? Though it differs from driver to driver, rotors should last roughly five weekends and pads can last anywhere from two to four weekends. In sympathetic hands, the engine and gearbox can last five seasons, though it’s common to get a top-end rebuild at the end of each season—the same interval at which most of the Eaton Truetrac differentials are given an overhaul.

There are some potential mods in the works which will help the Spec Mustangs branch out and stay competitive at faster tracks. The predicted cut in lap times with these, a 3.9 final drive and a lightened flywheel, looks like two seconds at the faster tracks. If this holds true, the newest iteration of the SMG (Spec Mustang Class) would run competitively in USTCC and SCCA T2.

Reduced running costs, growing class sizes, and a little more straight-line speed, why not? This should draw more into this burgeoning class. Once the new entrants spend a session or two in this newer, larger, slightly more expensive spec-series vehicle, they’ll learn it’s really just a friendly German Shepherd. A big canine with plenty of teeth, but a well-behaved one that won’t spontaneously clamp down on their ankle. The Spec Mustang, despite having this brutal air about it, was far more approachable than I’d anticipated.

About the author

Tommy Parry

Tommy Parry has been racing and writing about racing cars for the past seven years. As an automotive enthusiast from a young age, he worked jobs revolving around cars throughout high school, and tried his hand on the race track on his 20th birthday. After winning his first outdoor kart race, Tommy began working as an apprentice mechanic to amateur racers in the Bay Area to sharpen his mechanical understanding. He has worked as a track day instructor and automotive writer since 2012, and continues to race karts, formula cars, sedans, and rally cars in the San Francisco region.
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