07-12-06: Here in the States we are still driving Ford Mustangs with a live axle rear suspension design that’s a half century old. Since the mid 1990’s Ford enthusiasts have been wondering when Mustang would ever move into the now, and offer a modern independent rear suspension (IRS).
The SN-95 Mustangs were designed and launched without it. Then came the 1999-2004 SVT Cobras equipped with a cobbled together, half measure of an IRS that performed poorly. It gave IRS a bad name with owners and bean counters alike. While early S-197 Mustangs were planned to have IRS, bean counters won out and we once again were stuck with an “ox cart” rear suspension. All the while, Ford buyers in Australia have been enjoying world class IRS for years in a wide range of Falcon, Futura, and Fairlane models from mundane to insane.
Ford Australia’s latest version of the IRS found in the current Falcon is a world class design with multiple links, heavy duty construction for the rough roads in OZ and a growing list of accolades from the automotive press. With rumors that this system will find its way into future American Ford models, possibly even the Mustang, we thought we’d have a look at it.
Called “Control Blade IRS“, the package is based on a similar system used in the European Ford Focus and Jaguar's X-type. It has one beefy trailing link, two lateral links, and a toe-control link. All of those components are mounted to a lightweight drop-in sub-frame. Ford's Australian division chassis development manager Alex de Vlugt said, "The great benefit of Control Blade IRS is that it's been designed to separate suspension functions, allowing an optimal tune for varying conditions."
The stout forward trailing link, or control blade, is strong enough to keep unwanted wheel motions to a minimum. Further, the use of a stamped steel arm that connects to a cast upright keeps weight down. Along with the multiple lateral and toe control links, this unit has excellent resistance to wheel hop. In fact Ford Australia already has tuning in place for high horsepower applications with the BOSS 290 Falcons which come with a snarling 5.4 liter DOHC power plant.
In addition to being more flexible and compact for design and packaging, the Australian IRS is also cost conscious for Ford. This is course has always been the excuse for the Mustang being without IRS. In Australia they see significant savings by outsourcing its manufacture to well known American component supplier, Dana Corporation. They build the complete IRS package at their own facility adjacent to Ford Australia's Campbellfield vehicle assembly plant.
In fact, Dana actually did much of the design for the system. Through the co-location of Dana engineers in Ford's product development facilities, Dana and Ford were able to collaborate on the design and development of the independent rear suspension system. The collaboration has achieved significant cost savings. "By being involved in the early stages of the design and development of this system, we were able to capture potential synergies and identify and address issues earlier in the product development process," said Steve Hanley, vice president of Dana's Systems Integration Group.
The finished system consists of 78 components from 27 suppliers. It weighs slightly more than a live axle and its related components but the un-sprung weight which affects handling is dramatically reduced. We applaud Ford’s recent announcement that the Australian division will be involved if not completely chartered to develop the next generation of rear-wheel drive cars for the American market. Thus, the Dana IRS package is likely headed for a dealership in the States at some point in the future. We hope the Mustang finally gets its due.