Front suspension uses a third spring set up to tie the front and rear suspensions together. Roll hoops were revised for the 2007 RS Spyder, along with some other minor tweaks. (Photo: Porsche) » More Photos

Most noticeable, and contrary to popular rumour, the ‘wing’ elements mounted just forward of the dash bulkhead aren’t laptop holders for the data engineer. Rather, they are used to influence and focus the direction of the air as it travels to the rear of the car, rather than to serve as an additional wing element only to produce downforce. In fact, Steinhauser insists they aren’t there for downforce at all: ‘This is no wing profile as it is symmetrical. It is not adjustable or considered as an aero element.’

The front wheel pods now carry a more pronounced and open profile, akin to what was pioneered with the Lola 257 P675 car, and use a small vertical wing profile within the pod flow path help to keep air attached and concentrated as it exits from behind the front wheels. The height of the front bodywork covering the suspension has also been lowered, with a small bubble allowing space for the front rockers. Mirror position has changed too – both now being cockpit mounted. Sidepod height has also been lowered, with the transition from the sidepods to the rear wheel arches elongated and smoothed. Treatments behind the rear wheels with external ramps are also changed from the 2005/2006 car.

Porsche still retains a twin-element rear wing, but has sculpted the rear wing downwards from its twin post mounting points. The diffuser is to ACO regulations for size, with multiple strakes. Up front, the venturis have provisions for the addition/removal of strakes as necessary (and mechanics can be seen changing strakes at the track as more or less frontal downforce is requested).

As brakes have become a big area of development for size, weight and multiple pads, Porsche has left this system alone for the ‘07 RS Spyder. The same six-piston AP monobloc calipers and carbon discs (380mm front/355mm rear) are retained, used with single AP carbon pads. Even the practice of enclosing the discs with carbon shrouds (as also seen on the Audi) to better route thermals has been rejected, as Steinhauser explains: ‘The RS Spyder is significantly lighter than LMP1 cars. This influences brake performance and our necessary cooling.’

With the aerodynamic re-work, the resulting emphasis on tightly sculpted surfaces delivered an inevitable loss of free space to access the major components at the front of the car. To access the front damper/torsion bar arrangement, the front bodywork must be removed, followed by the carbon crash structure/splitter. To get to the power steering unit or to make a front anti-roll bar change, the removal of a third piece, a carbon enclosure, is required.

Although ease of access is sacrificed, the benefit of the lowered packaging is yet another detail Porsche maximized. Compared to its rival Acura, Courage and Lola LMP2 competitors, the transverse mounting of the dampers and third spring is a unique solution on the Weissach machine, providing a lower centre of gravity. While one might suspect a modest negative aspect of this arrangement suspended ahead of the front axle centerline, it actually has a positive effect in balancing the weight distribution of the rear-engined car.

Suspension development has remained largely unchanged since the Spyder's introduction; it's so good, the design and kinematics are still superior to the rest of the LMP2 entries. (Photo: Marshall Pruett) » More Photos

Torsion bars are used on the RS Spyder, connected to four-way adjustable ZF Sachs dampers and blade anti-roll bars. The front anti-roll bar is a unique split unit, with two separate pieces linked together at the blades by spherical bearings. The blades, housed inside the left footwell of the car, are a challenge to access in a timely manner. Rear suspension is affixed to a carbon structure carried atop the gearbox. Suspension adjustability has been retained from the first generation RS Spyder, with camber, toe, anti dive, anti squat, ride height and wheelbase available for alteration. Shims of varying yet specific thicknesses are used to adjust camber, toe, geometry and wheelbase.

WORKS OF ART
Of the many ornate parts on the car, none is more impressive than the front suspension rocker arms. Serving multiple purposes, and designed to withstand a multitude of forces acting in every direction, the piece is a work of art. Connecting a front pushrod to the damper, the third spring damper, the anti-roll bar and the torsion bar together, the unit begs further explanation. Sadly though, Porsche wouldn’t be drawn on its construction material or peak torsional force limitations, though Steinhauser did concede that a front rocker takes ‘five weeks procurement time’ from start to finish.

As pioneered in open-wheel racing in the early ‘90s, the RS Spyder employs a smart ‘third spring’ arrangement, not always a common feature on prototypes. The third spring, using dense plastic or phenolic ‘packer’ shims to set the desired compression of the third spring damper, ties the front and rear suspension together to limit the car’s critical dynamic ride height, allowing it to maintain an optimal aerodynamic platform without recourse to heavy damper springs. Depending on the circuit, the RS Spyder will run with or without a spring installed on the rear third shock.