Tom Wilson
January 27, 2014
Photos By: Courtesy of Ford Motor Company

Mechanically Speaking

So, what sort of Mustang did Ford build after polling the Mustang universe? The short answer is they modified the existing car until nothing old was left. As such the '15 Mustang, while still clearly referencing the '05-'14 Mustang architecture, is an all-new device.

Addressing this more thoroughly is Dave Pericak, Chief Nameplate Engineer and a man we'll be hearing much from as he's the highest-ranking person dedicated to the Mustang inside Ford: "…This is a clean sheet of paper. Of course, we had a basis to learn and launch from, but as we have evolved there is nothing carryover on this car. It is as clean as a clean sheet gets. All the parts are brand new."

Not one to quibble with the man who birthed it, but if you search long enough in the powertrain, there has to be a bolt, bearing, or crankshaft making the trip to the '15 Mustang unchanged. So let's give Dave his deserved poetic license, as he explains.

"We used a lot of the known basis of the S197. There is a lot of goodness in that car, and we've continued to tweak and evolve it over the years. We used that to launch the new designs and get where we are today."

"The car is so much more capable, and so much more precise," he said. "It is really going to shock you in a good way as to how much we have raised the bar in a good way through the design."

At this early stage Ford has not let loose with all the fundamentals, specifically weight and cost, but what can be seen says much about what remains hidden. Most fundamentally, the '15 Mustang retains the existing 107-inch wheelbase, has wider front and rear tracks, and as Ford confirmed, employs an independent rear suspension. That means a larger footprint than the today's car, which, barring exotic materials (extremely unlikely and none seen so far) or aggressive component design and machining (possible in places), means increased weight. An IRS suspension is traditionally heavier in this class of car than the out-going live rear axle, and so we're not counting on a lighter car.

Balancing that is a touch more horsepower, and when queried on weight, Mustang honcho Dave Pericak responded enthusiastically that the development team had met all performance goals and was "extremely enthusiastic" with the new car's performance—and thought we would be too. But he didn't say anything about weight.

That said, check out the '15 Mustang GT performance goal—beat the Boss 302! If that doesn't get your attention, we don't know what will. And that's not to match it only in raw stopwatch tests, but including the more subtle benefits such as precision and balance. In fact, the fleet of aspirational vehicles taken along on every Mustang development drive included the Porsche 911 and BMW M3, as well as the Boss 302. This is indeed aiming high, and given the engineer's happy faces and eagerness to spill all that the marketing folks would allow, it appears the target has been hit, or looks like it's going to be hit.

To meet these lofty goals the Mustang structure is more rigid with increased use of high-strength steel, increased gusseting (especially around the radiator support), and wears a stronger, stiffer, and lighter front crossmember. Greater precision and world-class handling were clearly on the agenda, and the chassis was made all new accordingly. Of course, the new chassis is stressed and packaged to work with the all-new IRS. Such provisions go deep, as the IRS packages completely differently than the outgoing live axle. It uses a subframe mounting system for the differential, which is based off of the familiar 8.8, and it feeds loads into the unibody at much different points than the live axle.

Just to be clear about it, there is no provision for a live axle anywhere in the '15 Mustang lineup, and for better or worse, we've doubtlessly seen the last live-axle Mustang from Ford. Insiders say retrofitting a live axle to the 2015 will not be easy. All but dedicated, mega-power drag racers will likely learn to live with the IRS.

Asked why Ford dropped the live axle, Dave replied with a little laugh, then said, "It's just time. I think it is really important as you decide to take the vehicle global, I think that's something important to that strategy.

"We've done a lot with the solid axle, we've taken it a lot farther than most people ever thought you could, we love where we've been and what we've done, but looking forward and taking the car global, I think that's key to the strategy, to have the independent rear suspension. And, you know, when we decided to do it, we did it right. I mean, this independent rear suspension is a world-class suspension, and we're pleased with how it's performing."

Performance Packs

Ford is offering a pair of Performance Packs for the new Mustang, the better for performance duty and the hardcore crowd. These promise eye-opening performance; the GT Performance Pack is said to definitely out-lap the Boss 302 on track and a Performance Pack 2.3 Ecoboost promises to combine exquisite balance with pleasingly torquey street oomph.

GT Performance Pack
• Torsen differential
• 15-inch, six-piston front brakes
• Cross-axis ball joints in IRS
• Monotube shocks
• Staggered fit tires: 255 front, 275 rear
• 19-inch wheels
• Front-end stiffening: K-brace, stut-tower brace, grille-opening reinforcement brace, cross-axis joint on lateral link
• Brake cooling via undercar diverter (not ducting)
• Larger radiator
• More aggressive spring, shocks, and sway bars

2.3 Ecoboost Performance Pack
• Larger radiator
• 14-inch rotor, four-piston front brakes
• Upgraded axle (no Torsen)
• Summer tires, 255 all around
• Chassis stiffening
• 145-mph top speed
• More aggressive spring, shocks, and sway bars