FACTfile - Alfa Spider 2006

Ride and handling

The new Alfa Spider has a wheelbase of 2528 mm, 175 mm shorter than that of the Alfa 159, with which it shares platform and suspension designs.

The suspension system is the outcome of an extensive and thorough development process aimed at achieving the highest possible levels of driveability and handling appropriate to a sporting marque, combined with optimum travelling comfort.

It combines a proven, high double wishbone front set-up with a new, sophisticated multilink rear configuration, the combination generating smooth, accurate steering response, exceptional stability and controllability – even when close to adhesion limits, and first class body control allied to remarkable comfort over all road surface conditions.

The 3.2 JTS versions of the new Spider further benefit from Alfa Romeo’s Q4 four-wheel drive system; a mechanical system enhanced by cutting-edge electronic technology to guarantee the smoothest possible power delivery and optimum traction under all driving conditions.

Front suspension
The Alfa Spider’s high double wishbone front suspension is an improved version of the set-up so successfully employed on the Alfa 156, and then further revised on the new Alfa 159. Its design is based on that universally employed in motorsport, offering precise control of wheel movement and affording the new Alfa Romeo outstanding dynamic performance allied to extremely sensitive, accurate steering.

Engineering improvements to the aluminium upper and lower arm set-up include an increase in the size of the coaxial damper spring to improve its capacity to absorb poor road surfaces, the use of a pair of dry friction sliding bushes to the aluminium upper arm for strength, reliability and a more progressive action, and a relocation of the steering axis closer to the centre of the wheel for improved cornering response. Additionally, the suspension is now connected to the chassis via a closed geometry frame, which is stiffer than the previously employed crossbeam.

From a dynamic viewpoint, the high double wishbone layout combines long wheel travel with outstanding control. This configuration offers the Alfa Spider maximum tyre grip, improved traction under extreme conditions, a self-alignment effect proportional to the lateral acceleration applied in a corner, superior steering precision and sensitivity, graduated steering wheel effort up to adhesion limits and the minimisation of pitching under extreme acceleration or braking.

Rear suspension
At the rear, the Alfa Spider employs a new multilink suspension system to maximise driveability, handling performance and ride comfort. Through a combination of transverse and longitudinal links, the system facilitates extremely precise wheel movements in the vertical plane, whilst limiting longitudinal and transverse displacements to maintain optimum wheel positioning under load. Pitching is reduced, and maximum stability under braking is ensured by the reduction of any tendency to understeer.

Key features of the new multilink configuration include a higher anchorage point of the longitudinal link to facilitate a longer, more flexible suspension stroke, an enlarged bi-tube spring damper unit for improved ride comfort, and an aluminium upright with a high rigidity hub supporting the connection bushes for both camber and longitudinal
links. In addition, the new set up features a rear hydraulic bush to optimise filtering of poor road surfaces, and a high yield steel crossbeam isolated from the bodyshell by four flexible bushes to dampen high frequency vibration.

Steering
All Alfa Romeos are renowned for their direct, lively and responsive steering feel. The Spider is no exception, and is fitted with hydraulically power assisted, speed sensitive steering which achieves a highly effective balance between low speed maneuverability and high speed accuracy and feel. With just 2.25 turns lock-to-lock and a ratio of 12.7 degrees of steer for every degree of steering wheel input, the new Spider offers the most direct steering in its class.

The telescopic steering column is divided into two sections for comfort and safety. The lower section is collapsible to ensure that steering wheel position is maintained relative to the driver during an impact. The upper section offers both reach and rake adjustment to the driver. A steel bracket and a rigid magnesium mount prevent vibration.

Careful matching of the steering geometry to the wheel arch volume has facilitated high steering angles even with the largest tyres fitted, affording the new Alfa a turning circle of just 10.7 metres between kerbs.

Q4 four-wheel drive
The 3.2 JTS engined versions of the new Spider are equipped, as standard, with Alfa Romeo’s Q4 permanent four-wheel drive system. Q4 employs three differentials, with a self-locking Torsen C unit at the centre of the system, which in normal conditions divides drive torque by a ratio of 57% to the rear wheels and 43% to the front – the rear axle bias promoting sporting handling appropriate to the marque.

Torque split between front and rear axles is constantly modulated by the central Torsen differential on the basis of available grip, with a maximum available bias of 72% to the front, and 78% to the rear. Modulation is mechanical and continuous to guarantee the smoothest possible power delivery, and the system is further enhanced by the full range of electronic stability controls to guarantee optimum traction and performance under all driving conditions.

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Passive and aktive

Safety

The new Alfa Spider is at the top of its category in terms of active, passive and preventive safety. It meets preventive safety needs with an adjustable cockpit that adapts perfectly to drivers of any size. The combination of a height adjustable driver’s seat and reach and rake adjustable steering, allied to an extensive glazed area, allows the best possible view of the road ahead.

User-friendly ergonomics allow drivers to operate all instruments and controls without taking their eyes off the road. And the new Spider’s excellent all-round visibility is further enhanced by the availability of rain, dusk and demisting sensors.

Passive safety
Within an all new bodyshell designed to provide maximum torsional rigidity yet absorb impact with maximum efficiency, the new Alfa Spider is fitted with five standard airbags, whilst height adjustable front seatbelts with pretensioners and load limiters, anti-whiplash front seat head restraints, three-point rear seatbelts, anti-submarining front seats and an FPS Fire Prevention System are all fitted as standard.

Airbags
The new Spider is equipped with no less than five airbags; 60 litre driver and 120 litre passenger dual-stage front airbags, driver knee airbags and front side airbags. Their operation is controlled by an electronic control unit that evaluates crash severity via a number of sensors located throughout the car.

Fire Prevention System
The FPS includes a cut-off valve and an inertia switch which immediately locks the electric petrol pump. This prevents fuel loss in the case of impact, roll-over or damage to the fuel lines. The fuel tank is formed in a plastic resistant to mechanical stress and fire. Special care has been taken over the location of key components within the engine bay, electrical system, fuel system and brakes to minimise the risk of damage. The new Alfa Spider’s interior trim is also flame resistant.

Active safety
The new Alfa Romeo’s servo assisted braking system features two independent crossover hydraulic circuits to ensure prompt, linear braking and minimal stopping distances. Spider versions powered by the 2.2 JTS engine are equipped with 305 mm ventilated front discs and 278 mm solid discs at the rear. The 3.2 JTS V6 version features larger, 330 mm ventilated discs and powerful, Brembo, four piston monobloc aluminium callipers at the front, with 292 mm ventilated discs at the rear.

The new Alfa Spider is equipped, as standard, with a comprehensive range of state-of-the-art electronic braking, traction control and stability systems: ABS anti-lock braking is combined with Electronic Brakeforce Distribution over all four wheels and Hydraulic Brake Assistance, whilst a sophisticated Vehicle Dynamic Control unit enhances cornering stability.

VDC is further augmented by Anti-Slip Regulation to limit wheelspin during acceleration, Motor Slip Regulation to modulate braking torque when changing down through the gears, and a unique Hill Holder function to facilitate smooth hill starts.

ABS with EBD and HBA
The Alfa Spider is fitted as standard with a Bosch 5.7 anti-lock braking system, one of the most advanced units currently available. The system incorporates an electronic brakeforce distributor with four active sensors, four channels and a hydraulic control unit with 12 solenoids. Because the active sensors can themselves process a wheel input signal, rather than passing it on to the control unit, the system can both activate more quickly and detect speed signals far closer to zero.

The active sensors are less sensitive to interference from electromagnetic fields and road surface heating and, because they can detect very low speeds, augment the efficiency of the satellite navigation system by allowing more accurate updating of data on the route covered by the car.

EBD distributes braking action over all four wheels to prevent them locking, and ensures full control of the car in all situations. To reduce brake pad overheating, the system also adapts its operation to both grip availability and brake pad efficiency.

Though primarily conceived to automatically increase brake force when insufficient brake pedal loading has been applied during an emergency stopping procedure, Hydraulic Brake Assistance can even help experienced drivers who have applied the correct amount of pedal pressure, by reducing braking attenuation time in all cases (the time between initial pedal loading and maximum brake circuit pressure).

VDC
This innovative switchable Vehicle Dynamic Control system is activated under extreme conditions when vehicle stability is at risk, helping the driver to control the car. As befits a true Alfa Romeo, however, VDC is a sporting system that does not interfere prematurely, allowing the full satisfaction of driver control to the limit of critical conditions. It can also be disengaged at the driver’s command.

The Spider’s VDC continuously monitors tyre grip in both longitudinal and lateral directions. If the car starts to slide, VDC cuts in to restore directional stability. It uses sensors to detect rotation of the car body about its vertical axis (yaw), lateral acceleration, and steering input. Comparing this data with computer generated parameters, the system establishes whether the car is cornering within its adhesion limits or if the front or rear wheels are about to lose grip.

To restore the required trajectory, VDC generates a yawing movement to counter that responsible for the vehicle’s instability by braking the appropriate wheel individually, and reducing engine power via the throttle.

Exceptionally smooth brake modulation and engine power reduction are key attributes of a system designed by Alfa engineers to maintain outstanding performance and driving satisfaction throughout its operation.

ASR
Anti-Schlupf Regelung (Anti-Slip Regulation) is an additional feature of the Alfa Spider’s VDC system, designed to limit wheelspin in cases of low road surface grip. This sophisticated system works at any speed and prevents the driven wheels from spinning by adjusting torque according to the grip coefficient detected at the time of slip.

The system recognizes loss of traction via the ABS sensors, and activates two different control systems to restore grip: in the case of both driven wheels spinning it reduces engine power via the throttle. If only one wheel spins, however, it is automatically braked; the resultant effect similar to that of a self-locking differential.

ASR not only optimises vehicle safety in conditions of minimal or constantly varying degrees of grip, but also greatly reduces mechanical stress to the differential and gearbox through effective control of low speed take-off and traction.

The system is activated automatically whenever the engine is started, but may be deactivated via a switch on the centre console. A flashing warning light indicates ASR operation, whilst a second light illuminates to indicate system faults or irregularities. ASR deactivation is required when snow chains are fitted to allow for their effective use.

MSR
The new Spider further benefits from Motor Schleppmoment Regelung (Motor Speed Regulation). MSR cuts in when a gear is shifted down abruptly under conditions of low grip, restoring torque to the engine to prevent skidding as a result of wheel lock-up.

Hill Holder
Also integral to VDC, the Alfa Romeo’s Hill Holder system helps drivers pull away smoothly from an upwards-facing hill start. Operating via the ESP longitudinal acceleration sensor when first gear is engaged and both clutch and brake pedals are pressed, the control unit maintains front calliper pressure for about 1.5 seconds after the brake pedal is released to eliminate the risk of rolling backwards and ensure a smooth pull away. Hill Holder does not operate when setting off downhill in first gear, but does so when reverse is engaged and the driver wishes to back uphill.

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