Lost Mustang History: Ford Designs an SLA and IRS for the SN95 Mustang

The SVE Mustang King Cobra (1994) and the SVE Super Stallion (1997) were two Ford engineering exercises built to explore modernization of the SN95 platform by the addition of state-of-the-art SLA (short-long arm) and IRS (independent rear) front and rear suspensions. Ford knew that the SN95 platform, with architecture originally designed in the mid-seventies for the 1978 Fairmont, couldn’t remain competitive or leading edge in the market for very much longer, much less meet upcoming Federal safety (gas tank location) or crash (structural integrity) standards. The SN95 platform itself was simply was an update of the original FOX platform (an all-new platform designed for the 1978 Fairmont and 1979 Mustang, later used for the Thunderbird, LTD 2, Lincoln Mark VII, and several other cars). The SN95 is so closely related to the FOX platform that most SN95 parts easily bolt onto earlier FOX Mustangs.

Why is the story of the King Cobra and Super Stallion story important? Because these two cars, along with the MN12 based Mustang production prototype, the FR500 showcar, and doubtless other lost engineering exercises, are an important part of the history of the Mustang. They show that Ford had a much greater vision for the Mustang than what we eventually received in production. They also show that Ford’s budget – as well as the vision and acceptance of the top Executives, was the constraining factor (with the exception of Jacques Nasser, who personally sponsored both the 1999 Cobra and the 2003 Cobra – and said at the time of the 1999 introduction “Isn’t it about time we offered an IRS on the Mustang…!”). Those constraining factors continue to this day, and in the case of the current Mustang originally cost it use of the full DEW platform and then before production an IRS suspension developed for the (dumbed-down DEW) S197 platform.

Ford’s Special Vehicles Engineering (SVE) organization was at the time the internal engineering arm of the Ford Special Vehicles Team (SVT). SVT was purely a marketing organization at the time, and as of this date is a shell of its former self with basic engineering and testing carried out by the platform teams rather than a separate organization such as SVE. This change was introduced (with some internal controversy) because of the severe engineering and quality issues introduced by SVE re-engineering the cars as they saw fit, with much less rigorous engineering and testing before production release. Warranty issues were first seen in the 1994 Cobra (magnesium seat brackets and front suspension bushings, differing from the standard parts) and (as the SVT products further differentiated their engineering from the base products) in the 1999 Cobra horsepower and cooling recall. Clearly a “post-engineering re-engineering” methodology had to stop and Ford eventually put an end to it. But before that, the two SVE cars shown here were examples of just that type of “band-aid” engineering. Only the supercharged 4.6 DOHC engine persevered, and it had more than its share of severe quality and warranty issues (perhaps the worst ever for SVT) as well (as this author personally suffered thru).

Let’s review the King Cobra and Super Stallion (from our Ford Motor Company concepts, prototypes,. and show cars section – with over 150 examples), along with images from the time:

SVE Mustang King Cobra

The SVE Mustang King Cobra came first, almost at the same time the production 1994 Mustang was being introduced. Due to cost constraints, the 1994 Mustang was introduced with ye olde iron pushrod 4.9 liter OHV engine. This was not what was originally intended when the SN95 platform was conceived (which itself was only a last-minute substitution for an MN12-based Mustang originally intended for the 1991 timeframe). Ford had planned to use the “modular” 4.6 liter engines from the start, including the 4.6 DOHC engine introduced 1993 Lincoln Mark VIIII. However cost constraints held Ford back, so the old engine would have to suffice for the time being. Meanwhile, the future of the Mustang was being examined internally with the King Cobra. Images of the King Cobra - and it’s very existence – have never been released or discussed by  Ford. It was purely an internal prototype of the originally intended SVT Mustang Cobra – a plan that was considerably dumbed down (and delayed) before final production in 2003.

The supercharged 4.6 is related to that of the Mustang Mach III, with changes suitable for production use. You’ll note that the layout below is very close to that of the 2003-04 Cobra.

Elements of the 1996 Mustang 4.6 V-8 (SOHC U& DOHC) can be seen here including the use of the Hydroboost braking system, the pre-production air filter, and the placement of the fuse box and other underhood elements.

Many of the engineering elements of the future 2003 SVT Cobra can also be seen here – from the supercharger placement (although not the same supercharger), to the expansion tank for the intercooler, to the shape and location of the MAF, air filter, and air inlet. The battery, however, is located in the trunk – something that would prove impossible for the eventual production car. Note that the power steering reservoir is located where the battery would normally be found and that would also change by necessity.

There was also an emphasis on building in anti-lift geometry in the rear suspension. It was apparent that this car would have a very heavy engine up front, and this architecture was necessary for handling and braking ability. Anti-lift would be an important benefit of the final production 1999 SVT Mustang Cobra IRS suspension as well.

Features

• IRS with special attention paid to achieving low unsprung weight and anti-lift geometry
• SLA front suspension
• PBR fr/rr brakes w/specifically-tuned ABS
• Torsen differential
• Unique body components – hood for clearance, and functional side scoop to cool rear suspension
• Unique interior trim

The Mustang King Cobra shows that SVE had in mind a demonstration of its suspension ngineering capabilities.  As we know, none of these major engineering elements made it to production. Nor has Ford been able to actually offer such a front and rear suspension on a production Mustang. It’s a shame that SVE and Ford fell so far after showing what they were capable of here, and again later on with the FR500.

Specifications

SVE program managers included Al Suydam and Steve Anderson. Team members included Ron Smith and Eric Tseng.

A number of issues were encountered in the development of this car (and the related show car Super Stallion – which perhaps was one and the same car underneath?). The chief problem was excessive heat in the shocks – pushrod operated, and located in a “tray” in the trunk. The side vents cooled those shocks, but only to a degree.

Also, of course, was the entire issue of cost: since the SN95 hadn’t been engineered for an SLA up front and an IRS in the rear, production costs would be excessively high – especially for a short run of 8-10,000 cars per year. As it turned out, as we now know for the 2003 Cobra, the SLA front suspension was dropped, the IRS was totally redesigned to make it considerably more production-friendly, and the supercharged engine would continue in development for a few more years before finally appearing in 2003.

SVE Mustang Super Stallion

While the SVE Mustang King Cobra was originally an exploration of intended things to come, the Super Stallion was nothing more than a show car (introduced at the 1997 SEMA show). However, it did reveal to the public for the first time the front SLA and rear IRS development work that had been done. Several magazine articles of the time showed detailed photos of the front and rear suspension. Unfortunately, none of these unique suspension pieces would ever be seen again, much less in production. However, the improved 4-valve cylinder heads, the T-56 (previously seen in the Mustang Mach III show car), and the use of front Brembo brakes were an early indication of things to come on future SN95-based Mustangs.

The bodywork of the Super Stallion takes a step forward from the King Cobra by providing proper room for much-needed larger wheels and tires. Custom front and rear fenders provide extra width and opening size. The King Cobra, given the standard early SN95 fender wells, was left at a strange angle in order to get the needed wheels and tires under the car.

Possibly this car was simply the King Cobra underneath, with the new engine added. In any case, when the car was revealed, the production 1999 SVT Mustang Cobra with it’s entirely different IRS suspension was already well in the pipeline and would be shown to the press 6 months later. The reworked 1999 Mustang was the result of a 750-million dollar (over-)budget project, led by Janine Bay, including the cost of the design and production prep of the IRS that was used in production.

This car, and the King Cobra, showed that Ford engineers were trying to give the Mustang a world-class suspension, despite the desperately outdated and unbalanced platform – and the intent to replace it with an entirely new platform after the turn of the century (delayed until 2005). A prior “last shot” at improving the FOX platform had been seen in the FR500, although that car was never (despite press releases to the contrary) intended as anything other than a show car.

Specifications

• Engine:
  • 5.4L “modular” V8 with improved 4V cylinder heads and 16 injectors
  • Flex fuel compatible
  • Dual MAF and throttle body assemblies
  • Garrett (Allied Signal) Positive Displacement Supercharger w/Cockpit Controlled Disengagement Clutch
  • Garrett Air to Water Intercooler
• Borg Warner T56 6-speed
• Suspension:
  • Front: SLA Front Suspension w/Koni DA shocks
  • Rear: SLA IRS w/pushrod actuated Koni DA coil over shocks mounted in the truck
• Brakes:
  • Front: Brembo 4 Piston w / 13″ x 1.25″ cross drilled and slotted rotors
  • Rear: stock Cobra rear calipers w / 12″ x 1.0″ cross drilled rotors
• Wheels/tires:
  • Speedline 3 Piece Racing Wheels (18″ x 8.5″ Front / 18″ x 9.5″ Rear)
  • Goodyear 265/40ZR18 Eagle F1-GS Fiorano Tires

Engine Output

Development Team Members

• Steve Anderson – Program Manager
• Bill Lane, Kevin Lambert, Dave May, Primo Goffi, Al Oslapas, John Moore

Photos

Press Release