2015 marks the 50th anniversary of the first Shelby-badged Ford Mustang, the 1965 GT350. With an all-new Mustang having hit the streets last fall, 50 years after the original, the first true GT350 since the 1960s is now in the final stages of development and it promises to be truer to the spirit of that first model than any of the cars to wear that badge since.
In 1964 as Ford was launching the Mustang onto to the market, it was an immediate sales success but Ford also wanted to give the car some real performance credibility as well. They were already collaborating with Carroll Shelby on the Cobra program and bringing him to help with development of the GT40 so it was natural to let them take a crack at beefing up the Mustang. Shelby’s mandate was to transform the pony car into something that could win SCCA B-production. Needless to say, Shelby succeeded brilliantly with Ken Miles driving the first GT350-R to victory in its debut outing at Green Valley Raceway in Texas on Valentine’s Day, 1965.
The original prototype GT350 and GT350R from 1965
While most Shelby-badged Mustangs that followed evolved into big-engined muscle cars, the GT350 was a lean, mean sports car tuned to win on road courses. It retained the 289-cubic-inch small-block V8 with improved breathing that pushed output of the street GT350 to 306-horsepower while the race cars got between 325 and 360-hp. Ever since Ford revived its relationship with Carroll Shelby for the 2007 GT500, the supercharged, high-powered Mustangs have been more adept at sprinting down a drag strip than around a road course but that all changes this summer.
Where the GT500 was all about maxing out the engine and then giving it enough brake and tire to keep things under control, the engineers responsible for transforming the 2015 Mustang GT into the new Shelby GT350 took a different approach, starting at the wheels and working there way up in an attempt to create the most track capable Mustang ever. From the early look we got at the car in the Ford Performance engineering garage, this is definitely not just a wheel and stripe package, but a thoroughly re-engineered car.
The new Mustang’s double ball-joint front suspension trades the iron knuckle for a version cast from aluminum with revise geometry
The crew formerly known as SVT had a vastly improved Mustang to start with when work began on this car several years ago, but even the all-new independent suspension system got a thorough going over. Up-front, the double-ball-joint strut setup gets aluminum knuckles to replace the iron versions used on lesser ponies. Since they had to engineer and cast a new part anyway, they took the opportunity to revise the geometry. The mounting points for the ball-joints have been spread further apart and relocated to reduce the virtual king-pin offset.
The base GT350 gets 295/35R19 Michelin Pilot Sport tires on 10.5-inch wide alloy wheels at the front which have also been spread further apart than other Mustangs. The revised strut linkage geometry are claimed to work with the new rolling stock to provide drivers with improved steering response and feel on either the street or track. At the rear, 305/30R19s are mounted on 11-inch wheels. The rear geometry remains approximately the same as other Mustangs, but that doesn’t mean changes haven’t been made.
The front carbon fiber wheels on the GT350R feature a plasma arc-applied ceramic coating to protect them from the heat generated by the immense brakes
Knocking things up a level for the GT350R is the first production application of carbon fiber wheels by a major automaker. These lightweight, yet strong wheels save a total of 50 pounds per vehicle, all of it unsprung mass which aids both handling and ride quality. These wheels are half an inch wider at each corner, 11-inches in the front, 11.5 in the rear, mounted with Michelin Pilot Sport Cup 2 tires with a compound unique to the GT350R. In a car of this performance caliber, the brakes can generate a remarkable amount of heat, especially at the front corners. In order to protect the wheels from this heat, Ford has adapted the Plasma Transfer Wire Arc process that they developed for the 2011 GT500 cylinder bore coating to apply a ceramic coating to the inside of the front wheels.
One of the advantages claimed for the carbon wheels in addition to their light weight is their durability. According to Adam Worth, Ford Performance suspension, wheel and tire supervisor, the carbon wheels can withstand similar impacts to aluminum wheels, but even if they crack, the properties of the resin means that the cracks don’t propagate the way they do with aluminum. Under similar conditions, the aluminum wheels will eventually lose air while the carbon wheels keep going.
The GT350 gets symmetrically wound rear coil springs for more consistent at the limit responses
During testing, the engineers noted a slight difference in the behavior at the rear end from left to right in extreme conditions. They eventually traced the difference to the rear coils which are normally identical and interchangeable. As the coils compressed and stretched on each side, they applied a longitudinal reaction force in opposite directions on each side which yielded a slightly difference response in left and right turns at the limit. The solution was to produce a new coil for the left with an opposite twist from the right coil. This in turn necessitated a new casting for the lower control arm with a matching pocket for the spring. It doesn’t seem like it should make much difference, but that’s the sort of attention to detail that drivers will notice when they draw out everything the GT350 is capable of.
While the GT350 is engineered to be the most track-capable Mustang ever, it also has to work on the street as a daily driver. In order to achieve a no-compromises balance between these two extremes, the GT350 has the first-ever Ford application of magnetorheological dampers (MR dampers). This is not new technology, having been invented at GM in the early-1980s, with the first production application coming in 2002 on the Cadillac STS. Since then the technology has been used by Ferrari, Audi, Acura and Range Rover as well.
The MagneRide dampers add about 10 pounds in total system weight, but that is more than compensated by the handling and ride improvement
The GT350 uses the third-generation MR dampers which feature dual electromagnetic coils to energize the iron particles in the damping fluid. The dual coil setup which debuted on the 2013 Camaro ZL1 reduces the response time to change the damping rate from the already fast 20 milliseconds to just 7 ms. As the fluid is energized, the viscosity is changed resulting in real-time continuously variable damping that can yield a comfortable ride on real world roads as you drive home from a weekend track day. The MR dampers are standard on every GT350.
At the track, robust and consistent braking is just as important as the ability to go and turn. Ford engineers developed the braking system for the GT350 in-house and then worked with Brembo to manufacture the parts. Six-piston monoblock calipers get a grip on the massive 15.5-inch front rotors while four-piston calipers clamp the 15-inch rears. While you might expect to find carbon-ceramic brakes on a car of this performance caliber, Ford Performance director Dave Pericak claims that the metal rotors used on the GT350 provide fade resistance equal to composite parts.
The two-piece rotors have aluminum hats and iron friction surfaces
While that may be true, these rotors are still heavier than carbon ceramics but even here Ford has done some interesting stuff. The outer friction surfaces of the rotors are cast from iron while the central hat that mounts to the hub is cast from aluminum. However, unlike similar parts from Brembo and other manufacturers that have these parts bolted together, Ford has a unique construction.
Radially-mounted, brass-coated, steel pins slide into holes around the interior of the iron ring. The assembly of friction ring and pins are then placed into a mold where the aluminum hat is cast in-place. This construction allows the friction surface to expand and contract independently of the hat as the brakes heat and cool while minimizing the heat transfer to the hub. The use of fixed rear calipers precludes the use of the integrated parking brake used on other Mustangs so the rear rotors also feature a drum-in-hat parking brake.
The most obvious change to the GT350 is the front end. The Shelby actually has completely unique bodywork from the A-pillar forward with wider aluminum fenders with functional heat extracting vents behind the wheel arches. The entire front fascia and hood are also unique to this variant. The grill leans forward a bit more with a more prominent lower splitter which aids in generating downforce at speed. The hood is more than an inch lower than those on other Mustangs and lacks the central power dome. In addition to cooling air for the engine, the grille also provides airflow for the standard oil and transmission coolers. The openings in the lower front provide air that is channeled to the front brakes while slots at the outer edge feed the air curtains that flow across the face of the wheels to reduce drag. A standard differential cooler is also included at the back of the car. Underneath the lowered front fascia, Ford has integrated a carbon fiber radiator support structure that this 24 percent lighter than the steel version used elsewhere.
Erick Zinkosky, lead development engineer explained that because this car will likely be used extensively at tracks around the country, the team tested at least 15 different tracks through the course of 2014. One of those of course was the Nurburgring Nordschliefe where spy photographers caught the car in July of last year. Before the car is signed off for production, it must go through a 24-hour durability test at the track. Before starting the test, their top driver sets a benchmark time and then the rest of the team must lap consistently within three percent of that lap time for the full 24 hours. During the test, the only items that can be changed in addition to fuel are wear items such as tires and brake pads. If anything else breaks or they are unable to meet the lap time bogey, the car fails.
All of this attention to detail in the development of the dynamic components of the new GT350 bodes extremely well for this car. Combine it all with the new 5.2-liter flat-plane crankshaft V8 and this certainly has enormous potential and Carroll Shelby would likely have been very proud to have his name associated with this car. However only the street and the track will confirm that and I can’t wait to try it out in the near future.
