Suspension

Suspension  - Overview - Volvo S40

The advanced, independent suspension system employs spring struts at the front, the geometry of which has been carefully calculated to provide quick and precise steering response, enhancing the car's sports appeal. The rear suspension is a sophisticated multi-link system. This permits a small degree of passive rear wheel steering when cornering, which helps to maximise stability and control. Anti-roll bars also feature at both ends.

DSTC, EBD and EBA

The Volvo S40's carefully honed mechanical set-up is supported by the DSTC (Dynamic Stability and Traction Control) system, which is standard on every model. This prevents wheelspin or the risk of skidding by either braking the wheel that has lost traction (up to 25 mph) or, at speeds above 25 mph, by reducing engine power and using extra sensors to detect the onset of a skid. The system then automatically slows the appropriate wheel to restore control. It ensures that the driven wheels get exactly as much power as they can transfer to the road.

All Volvo S40s benefit from ABS brakes with EBD (Electronic Brake Distribution) and EBA (Emergency Brake Assist) which senses an emergency stop and automatically brings the car to a halt in as short a distance as possible.

Driving Dynamics: Steering, Brakes and Transmissions

The Volvo S40 uses an electro-hydraulic power steering system that has been developed to optimise driver feedback and response. This helps the driver to place the car accurately on the road and to assess the available grip.

Ventilated disc brakes are fitted at the front. The disc size is adapted to engine power and wheel rim size, up to a diameter of 16in (16.5in for D5). As you'd expect from Volvo, an anti-lock braking system is fitted as standard and this is joined by EBD (Electronic Brake Distribution), which constantly distributes braking power between the front and rear wheels to ensure maximum retardation regardless of the road conditions or how the car is laden.

Every Volvo S40 is also equipped with EBA (Emergency Brake Assist). This system automatically senses when an emergency stop is required and adjusts the braking pressure so that the car comes to a halt in the shortest possible distance.

The 1.6, 1.8, 2.0 litre petrol engines, 1.6 diesel and 1.8F are mated to the latest generation of Volvo's five-speed manual gearbox, which has a triple synchromesh to provide faster, more positive changes.

The T5 engine uses the six-speed manual gearbox that was developed for the high-performance Volvo S60 R and V70 R. The ratios have been carefully matched to the engine's characteristics so as to combine strong acceleration with a high top speed. The gearbox has a triple synchromesh and a reassuringly direct shift action.

The Volvo S40 2.0D is fitted with a six-speed manual (although not the same unit as that fitted to the T5). The ratios have been chosen to complement the diesel's 320 Nm of torque and to provide effortless pull throughout the engine range. The S40 2.0D is also available with the new Volvo Powershift transmission which was introduced as an option in early 2008, this six-speed unit features twin wet clutches to provide the gear changing comfort of a fully-automatic transmission with the performance of a manual gearbox.

Operating as two parallel manual gearboxes, Powershift has twin wet clutches that work independently of one another. One clutch controls the odd gears (1, 3, 5 and reverse) while the other handles the even ratios (2, 4 and 6). The two clutches operate alternately with one engaging while the other disengages, like a slip clutch. This means that at the same time as the engine gets full power and maximum thrust in first gear, second gear is placed ready to be engaged. And when second gear has been engaged, third gear is readied, and so on. This gives a continuous flow of power without any disruption in power delivery or any torque loss. This results in extremely fast and smooth gear changes whilst maintaining acceleration allowing 0-60mph to be reached in 9.1 seconds and boasts a top speed of 127mph.

Apart from gear changing comfort and high performance, Powershift also contributes to delivering improved fuel efficiency. The Powershift Automatic offers an impressive combined fuel consumption of 47.1mpg and a CO2 figure of 159 g/km in the Volvo S40.

Powershift gives the driver an automatic transmission that permits sequential gearchanges, just like with Volvo's Geartronic transmission. The difference is that with Powershift even manual gearchanges take place without any time or power losses. Also, unlike a conventional automatic transmission, Powershift does not need a torque converter, planetary gears or multiple wet clutches, there is also none of the added torque losses that these features bring.

The D5 turbodiesel comes as standard with a six-speed manual, with Volvo's five-speed Geartronic transmission available as an option. The Geartronic system is fully adaptive - it automatically adjusts its shift patterns according to an individual's driving style and can be shifted into 'manual' mode if required. Geartronic is also available as an option on the flagship T5.

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