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Inside Look at Thomas Herb’s Wild 2012 Road-Race Ford Mustang
Über-Stang: What happens when German car specialists apply their expertise to an iconic American pony car?
Fall-Line Motorsports in Buffalo Grove, Illinois, is known for building championship-winning German race cars. Customers’ successes in professional and amateur racing is widely known in sports car circles. An impressive wall of trophies greets every visitor who walks through the front door.
Many of cars that Fall-Line builds are for customers of the nearby Autobahn Country Club. This symbiotic relationship between Fall-Line and the club results in some of the highest-quality race car builds in the world. So, when Autobahn member Thomas Herb commissioned Fall-Line Motorsports to apply its build philosophy to a Mustang, the result was bound to be impressive.
Herb reasons that even though his car ownership resume is filled with BMWs, his latest project was a Mustang for practical reasons.
“Back in 2011 I was racing in SCCA [Sports Car Club of America] and the BMW I was driving was uncompetitive in the T2 class,” Herb says. “We began to search for an alternative platform. The SCCA allowed the Mustang GT into T2 for 2012 and we thought it would be very competitive. It had a lot of power, and torque and could be just the car we desired. Unfortunately, the SCCA subsequently saddled it with additional weight penalties and a small engine air restrictor that limited its performance, so the car was not as competitive as we had hoped. After two very frustrating years and lots of development the team at Fall-Line and I decided to abandon the T2 class and build the Mustang into a full-blown race car. We made a few modifications, one at a time, until I was at Sebring in 2014 and blew apart my clutch—again. I decided that after we got the car back to Fall-Line, we’d go all-out.”
Besides offering open lapping sessions for members, the Autobahn Country Club sanctions its own independent racing series for members. Unrestrained by the SCCA’s T2 rules, the crew at Fall-Line could make modifications for racing under less stringent Autobahn Member Racing regulations.
Herb explains, “The Mustang received considerable upgrades that pushed it beyond club racing classes like in SCCA. As a member of the Autobahn Country Club, I wanted to build it to race in the GT Challenge series, which is a very competitive inter-club series that has everything from Porsche Cup cars, BMW M3s, Corvettes, Trans AM TA2, and many others across five performance classes. The Mustang is classed in GT4. We also race it with HSR where it is very competitive in its run group. Typically I am up against Porsches, BMWs, and Camaros.”
Autobahn Member Racing’s GT Challenge series is very much a “run what you brung” class, where cars are classed primarily upon a power-to-weight ratio. Sequential gearboxes, aero devices, and live-axle suspensions are factors that adjust the final value in an effort to balance the field as best as possible.
Fall-Line chose components that not only made the Mustang faster but more reliable under racing conditions. Case in point: Fall-Line equipped the Mustang with a Drenth DG500 sequential transmission. The Dutch company’s six-speed gearbox not only reduced lap times via quicker shifts but also is more durable than upgraded street ’boxes.
“For a race car, a sequential gearbox is an easy sell,” says Fall-Line’s co-owner, J.P. Novelli. “Over the course of a season, you can either keep rebuilding broken street gearboxes or you can use a bulletproof sequential. Over time, a sequential pays for itself.”
Surprisingly little was needed to adapt the Drenth six-speed to the S197 chassis. A billet aluminum adapter plate mates the Drenth six-speed to the engine via a SN95 T56 bellhousing. The talented Fall-Line fabricators built rear transmission mounts and an adapter to fit an OEM-replacement driveshaft from Dynotech. Asked whether the 7 1/4-inch, triple-disc Quarter Master clutch would act like an on/off switch, Novelli counters, “Nope. The clutch is surprisingly smooth.”
For power, Fall-Line tapped Hutter Racing Engines to build a maximum-effort Coyote engine. Hutter turned the wick up to the max and delivered a 600hp, 9,000-rpm monster to fit between the strut towers of Herb’s Mustang. Ed Senf of Engine Management Sales set up the AEM Infinity fuel injection system. A sensor in the sequential shifter handle tells the AEM module to either cut the ignition during upshifts or blip the throttle for smooth downshifts. Fall-Line’s Rob May did the final calibration on their in-house chassis dynamometer.
To make sure the Hutter-built mill is fed a steady diet of Sunoco 260 GT Plus, six fuel pumps were installed to suck the 104-octane gasoline from a 26-gallon, rear-mounted fuel cell. An endurance racing dual dry-break system was installed to hasten refueling for endurance events.
The tricks in the trunk didn’t end with the fuel system. Coolers for the gearbox and differential were mounted horizontally with fans that suck air from the interior via beautifully fabricated air horns and ducting through the trunk.
When we photographed Herb’s Mustang, it was about to receive a full military-spec wiring harness, so the AEM Infinity module was mounted to the engine—but in typical Fall-Line fashion, they applied temperature indicator labels to the module to make sure it didn’t get too hot. Future work is also planned to optimize the exhaust system, which currently features Kooks headers, H-pipe, and Borla mufflers.
The suspension is another standout feature of this car. Because of the freedom offered by the GT Challenge rules, Herb and Fall-Line chose a more radical—and race-ready—suspension solution from Griggs Racing. Up front, the entire OEM MacPherson strut setup was chucked in favor of a Griggs Racing SLA (short, long arm) suspension. The SLA suspension features improved suspension geometry and camber gain from a fabricated crossmember, fully adjustable control arms and antiroll bar, and billet aluminum uprights.
Out back, the suspension work continued. A Griggs Racing torque arm replaced the factory three-link setup, and the axle is located laterally via a Griggs Racing Watts link. Most solid rear axles are, by design, “straight.” While this maximizes straight-line traction, cornering performance is compromised because rear tires generate more cornering force with a couple degrees of negative camber. However, the pièce de résistance on Herb’s car comes from Australia: a “cambered” rear axle. Developed for Aussie V8 Supercars, the Race Products camber kit on Herb’s Mustang transfers torque from a Drexler limited slip differential via constant velocity joints and wedge-shaped spacers at the ends of the axlehousing to adjust the rear tires’ alignment. Herb is pleased with the benefits. He says, “The added rear camber really helps with the rotation of the car in corners and allows me to get the power down sooner as I transition through the corner.”
Custom-valved JRZ dampers by Fall-Line and Hyperco springs were built for all four corners. The front brake package specified large 378mm rotors clamped by massive six-piston Performance Friction calipers, while the rears featured four-piston Brembo calipers and 355mm rotors on custom-made brackets and hats. The brakes were housed inside 18x11 HRE forged aluminum wheels wrapped in 305/645 Pirelli slicks.
Herb “works” inside an all-business interior. A TIG-welded competition rollcage, Recaro racing seat, and Safecraft belts and nets were installed to keep Herb as safe as possible. When the AiM Sports MXL data-logging dashboard indicates 9,000 rpm, Herb pulls the billet aluminum Drenth sequential’s shifter handle. He steers the Flaming River rack with a suede-wrapped Momo wheel.
Speaking of driving, Herb gushes about the car’s performance. “It's fun! It has a lot of power and can really put it down. Running through the Drenth Sequential Transmission is a rewarding auditory experience. It has massive brakes to provide the stopping power. It is fun to take someone deep in to a corner and surprise them!”
But how does the Mustang compare to the other cars Herb has raced? “It is a very different driving style compared to my wide-body BMW,” says Herb. “The Mustang requires a little more patience. While the Mustang corners exceptionally well, you have to rotate the car through the corner before going to full-throttle.”
Herb says, “The best thing about the Mustang is the sound! American V-8 muscle—there’s nothing like it. It jumpstarts your adrenalin. Running down a long straight working up through the gears, taking it close to redline . . . It sounds awesome. It is a great feeling after a race when a corner worker or spectator comes up to me as says how much they liked seeing the car, but loved the sound it made.”
Herb goes on to say, “Most of the cars in the Fall-Line club race group have nicknames. I came up with Uber-Stang one day in a social media post, and it stuck.” It is a fitting name for an iconic American car built by German-car specialists.
Project cars are never done. What’s next on the list for the Uber-Stang?
“Fall-Line has really covered all the bases with this car, but this winter we will be replacing the dash and doors with carbon fiber pieces and installing a new AiM dash system and camera. In the spring my goal is to work with Fall-Line to further dial in the suspension and fine-tune the performance to get the Uber-Stang to the next level of performance.”
We can’t wait to see—and hear—Herb’s Uber-Stang at the next event.