The ’15 Mustang’s much ballyhooed independent rear suspension is described by Dave Pericak
To make the worst kept Mustang secret official, Dave confirmed the '15 uses an independent rear suspension. He described it as a "world-class, integral-link suspension designed specifically for Mustang... it improves stiffness and reduces compliance for more precision." Few details are available other than the IRS geometry has double the anti-lift under braking and two times the anti-squat during acceleration than the outgoing suspension for flatter handling. Also, it is based on the 8.8-inch differential, and expect to see all the good options available for the Boss 302 to reappear in the '15 Mustang GT—such as the Torsen limited slip. Furthermore, Ford is fine-tuning differential construction so the V-6 car's diff will be lighter and the V-8's stronger but heavier. Dave confirmed the GT gets monotube shocks at the rear as well.
A major part of the Mustang chassis story is that after the IRS was designed, the design team concluded they absolutely needed to widen the rear track 70mm. The front suspension had been widened by 15mm early in the program for performance reasons, and after much discussion, was not widened again when the rear was. This decision to widen the rear track was driven strictly by styling concerns says Dave (his chassis team met all of the handling objectives without the wider track), but it did mean a major effort revising the already designed IRS and everything it influences outward late in the program. The commitment to make this work for the better of the car shows the dedication of the whole Mustang team to the cause.
A MacPherson strut front end was retained for the new Mustang, but it is absolutely all new, including the front subframe (K-member) which is stiffer, lighter, and stronger. This allows for smaller diameter, better-riding sway bars because the front end twists less. Overall, the chassis is stiffer by an unspecified amount as well.
You might assume that the front suspension shares some hardware from the prior Mustang, bu
An exciting front suspension development is double-ball-joint geometry at the outer end of the lower control arm. This is a definite step up in suspension design from previous Mustang practice—it's more of a BMW trick—and it delivers increased precision through reduced wheel load lever arm, improved road feel, and wheel-rate stiffness. Not without its challenges such as cost and increased steering friction that demand careful engineering to reduce, this was still one of those improvements everyone wanted but management thought too pricey until a blind back-to-back test was arranged. The double ball-joint was approved immediately.
Put together, the front and rear suspensions yield "an extremely well-balanced vehicle," Dave said. He stopped short of stating the new GT will out-lap the Boss 302, instead saying he wasn't "making a promise, but [the development team] are on track to do that." To our ears, the message was Ford is emphasizing handling on the new Mustang, a most welcome development.
Another double-ball-joint advantage is increased room to package larger brakes—a definite need on the '15 as the stoppers range all the way up to 15-inch discs. In fact, Dave's enthusiasm peaked when describing the brakes. "All this hardware combined with the booster improvements and the pedal-ratio improvements gives us a braking system that we have just never had on Mustang before. It is absolutely phenomenal and confidence inspiring. It is really, really exciting."
So far, only the basic specifications for the front brakes are known, but they do point to a quantum leap in braking performance, especially when factoring the gains from the flatter-reacting suspension.
Entry level in the V-6 and 2.3 Ecoboost models is a two-piston floating caliper atop a 12.5-inch rotor. All Mustang GTs and 2.3 Ecoboost with the Performance Pack sport 14-inch rotors under fixed four-piston calipers that Dave characterized as similar to but more capable than today's Brembo package. He said the calipers are larger, stiffer, and generate more torque than today's four-piston units, and the whispered word is this is actually the best performing brake package.
Of course, there's more. Mustang GTs with the Performance Pack move to those pizza-pan, 15-inch rotors with fixed six-piston Brembo calipers. Again these calipers are larger, stiffer, and boast 15 percent more pad surface area than today's Shelby GT500.
Also mentioned, all Mustang calipers are aluminum, and the rear brakes have been increased in overall size and thermal capacity. Up front, the large brakes on the Performance Packages are cooled by under-car air diverters as well. These are similar to brake cooling ducts, but use fixed panels to scoop and flip air to the front brakes. There are no brake-cooling ducts in the front bodywork.
The tire manufacturers, compounds, and other details were not finalized at press time, but tire sizes were. Base 17-inch and 18-inch fitments wear 235 tires; 19-inch wheels get 255 tires; the 20-inch option comes with 265 rubber. All tire fitments are square—the same size at all four corners, except for the 5.0-liter Performance Package, which gets 275s at the rear on 19-inch rims.
When Can You Buy One?
Ford spokespeople were adamant Mustang will be sold world-wide unchanged from U.S. specification unless local regulations demand otherwise. The sequential taillights are banned in some countries, for example, rear foglamps can be required, and there will be righthand-drive models (late availability).
Because Mustangs are a rare, premium sports car overseas, Ford can charge more for them there. Asked if this was a significant financial gain, and thus helpful in getting some of the high-specification hardware through the approval process, Ford said no.
While there may have once been a plan to offer the '15 Mustang on the car's exact on-sale 50th anniversary—April 17, 2014—that is not the case. First deliveries are now planned for the last quarter of 2014, although orders could possibly be placed by the time you read this. Coupes will appear first, with the convertibles slightly delayed, perhaps two months.
All Mustangs will be built at the usual Flat Rock, Michigan plant. Expect fewer standalone options—Ford says that even with the additional engine, the ordering process will be less complex than with the current car.
Pricing, of course, will be the last '15 fact released. We feared Ford would make the car so capable and urbane that it would migrate above its populist roots, a well-anticipated question by the Ford team. Dave's response: "(We're) not ready to share the price, but we are happy where we ended up." Keeping the Mustang affordable was mentioned as a key goal by more than one team member.
Ultimately, even after our limited exposure to it, we are more sure about this new Mustang than any other in our 26 years of professional experience with the marque. Normally it takes us months to warm to a new design, but we've been excited by the '15 from the instant they slid the sheet off it in the design studio courtyard—when we felt a bit guilty for having doubted if Ford knew their car well enough to "get it."
Well, Ford definitely gets it. The personality looks spot-on with performance we didn't dare dream of.
We can't wait to bring it to you in all its variations.