- Volkswagen Group Procurement Nominates Strategic Partners
- WRC: Volkswagen Duos at the Front in the Finland Shakedown
The second generation of 4MOTION all-wheel drive is now available in the Golf
Permanent all-wheel drive for the powerful TDI and FSI models in the range
Wolfsburg, August 2004. With immediate effect, the new Golf also channels its power into the road via 4MOTION all-wheel drive. It’s available with a 1.9 TDI, 77 kW (105 h.p.) engine and a 2.0 TDI with 103 kW (140 h.p.). In only a few weeks, these will be joined by the powerful Golf 2.0 FSI with 110 kW (150 h.p.) as 4MOTION.
Once again, the Golf has proved to be Europe’s most successful car in the first half of 2004, and it’s now a front and rear-wheel drive car all rolled into one: As is generally known, the standard Golf is a front-wheel drive car – the safest type of drive train as long as the drive is “only” going to two wheels. When the other two wheels come into play in the Golf, an electronically controlled Haldex transmission unit splits the engine power between the front and rear axles.Other than the Audi A3, there’s currently no other directly competing model in the same class that’s available with permanent all-wheel drive – a system that offers increased performance and active safety not only on dry roads but also in the wet, ice and mud.
Latest generation of 4MOTION: Faster, quieter, easier to service and superior to rear-wheel drive
4MOTION all-wheel drive has been improved again in many aspects for use in the new Golf. Compared to the first version presented in the Golf in 1998, the second generation of 4MOTION operates with greater speed and sensitivity and is quieter as well. At the same time, it doesn’t need as much servicing (60,000 km instead of 30,000 km for the oil change and the filter only every four years). What’s more, the Haldex transmission unit mounted directly on the rear axle is now significantly more compact.
It’s a fundamental principle that all-wheel technology is advantageous particularly in the wet, ice and snow, and is superior to rear-wheel drive. However, even on dry roads, 4MOTION handles cornering forces better and therefore promotes active safety. The reason for this is well known: With 4MOTION, power can be transmitted variably to all four wheels using electronic control. This means each wheel gets the appropriate amount of power for the road and grip conditions prevailing there.
PULLING POWER:The Golf 4MOTION can hook up as much as 1800 kilograms
All-wheel drive also offers significant advantages when it comes to towing trailers: On inclines up to 8 percent, the new Golf 4MOTION is capable of towing 1800 kilograms of trailer load – that’s a significant achievement in this class. On inclines up to twelve percent the limits on the tow hitch are 1500 kilograms for the Golf 1.9 TDI and 1600 kilograms on the Golf 2.0 TDI.
OFF-ROAD CAPABILITY: Underbody guard for engine and gearbox as well as off-road package
Volkswagen offers an optional underbody guard for the engine and gearbox to protect them against branches and flying stones. In addition, an off-road package is available featuring a firmer shock absorber set-up and 20 millimetres more ground clearance. The all-wheel drive Golf reveals itself by the 4MOTION logo on the rear end, visible twin exhaust tailpipes and the special 4MOTION gearshift grip.
4MOTION in Detail
An electronically controlled Haldex transmission unit distributes the power between the front and rear axles
Electronically controlled: The most important technical element of 4MOTION is a latest generation wet-running (oil bath) multi-disc clutch.It’s called the Haldex transmission unit, since it was developed by Volkswagen in conjunction with our system partner for many years, Haldex, in Sweden.Compared to a straightforward mechanical Torsen differential, the Haldex transmission unit offers the decisive advantage that it can be electronically controlled.As a result, it harmonises perfectly with the anti-lock brake system (ABS), traction control (ASR), the electronic differential lock (EDS) and the electronic stability programme (ESP) – all of these assistance systems are installed in the Golf as standard.
Axles linked by pressure: As soon as there’s any difference in the rotation speeds of the front and rear axles, two annular piston pumps located within the multi-disc clutch itself are activated. These build up pressure in the transmission unit and thereby “link together” the two axles.They only take effect when the input and output shafts of the transmission unit are no longer turning at the same speed.After all, it’s only then that torque splitting is necessary.
At least ten percent always goes to the rear axle: The amount of torque transmitted can be varied by altering the pressure exerted on the clutch discs. This makes it possible to control the powerflow between the front and rear wheels. The transmission unit performs infinitely variable torque control (in fact, the driver scarcely notices what is happening) from zero up to full transmission – a 50:50 split of the propulsion power between the front and rear wheels. Normally, in other words when the car is driving straight ahead and there’s no difference in grip between the wheels, 90 percent of the propulsion power is sent to the front axle and ten percent to the rear. The only thing the driver really notices is that the Golf 4MOTION succeeds in retaining neutral handling characteristics and unerringly staying on course in practically any situation.
It’s all down to the CAN bus: The Haldex transmission unit is driven by the cardan shaft. The electronic control unit for the transmission unit gets all the important drive and engine information via CAN bus. This includes signals from the wheel sensors, the ABS and ESP as well as information about the accelerator pedal position and engine revs. Based on this data, the 4MOTION control unit regulates the level and trend of the hydraulic pressure that acts on the clutch discs.
Quick response time: “Commands” from the electronic control unit are carried out extremely rapidly by the transmission unit: The full pressure is applied after a rotation angle of only 45 degrees, in other words at the start of the first revolution after receiving the command in the form of an electronic signal. This generates the corresponding torque at the rear axle. Furthermore, the compact transmission unit is very robust; it can transmit up to 3200 Newton metres to the rear axle.
4MOTION better than ever: The details of the all-wheel drive have been made even more perfect than the 4MOTION system used in the fourth generation Golf. Here’s a review of the improvements:
– Clearly optimised low-temperature response characteristics and significantly longer service interval (oil: 60,000 km / filter: four years) by changing over to synthetic oil, doubling the oil volume and improving the oil flow.What’s more, maintenance is easier because access to the transmission unit has been improved.
– Reduced natural frequencies, no droning when stationary and a generally reduced noise level have been achieved by minimising the static basic torque and optimising the gearbox mounting.
– Compatibility with the ESP system has been improved by minimising the dynamic basic torque.
Four-link suspension for front and all-wheel drive: In addition, the Haldex transmission unit is now mounted directly on the rear axle. In contrast to the former Golf generation, the new Golf features the same innovative, new four-link suspension on both the front-wheel drive and all-wheel drive versions. Background: The previous model had a twist beam rear axle in the front-wheel drive configuration whereas its 4MOTION model featured multilink rear suspension for design reasons. The four-link suspension in the new Golf is hardly any more expensive than the twist beam rear axle and can be used across the range. As a result, the best system can be used for all propulsion types.
Four-Link Suspension for Front and All-Wheel Drive
FOUR-LINK SUSPENSION: Combining a high level of driving comfort with optimum handling characteristics
The key development objective for the current generation Golf in terms of chassis and suspension was clearly defined as follows: To achieve an alliance of cross-class driving comfort and ultimate handling characteristics that was as yet unparalleled in this class. Furthermore, the driving behaviour was intended to offer outstanding road safety and exact precision combined with a high level of agility. And this irrespective of whether the propulsion power was being sent to the front wheels or the front and rear wheels.
A suitably cultivated suspension-strut-type front axle with a lower A-arm and the completely new four-link suspension on the rear axle laid the best possible foundations for achieving these objectives. After all, these axle concepts made it possible to fulfil all the set objectives optimally – including the requirements on an all-wheel drive system.
Rear axle determines the driving behavior: The way a car handles when driven is significantly dependent on the configuration of the rear axle. It’s essential to use a complicated multilink design in order to achieve outstanding driving dynamics combined with a highly comfortable drive. That’s because the multilink suspension makes it possible to configure the longitudinal and transverse dynamics specifically and almost totally independently of one another.
Neutral driving behavior: Parameters such as the toe and camber of the wheels determine the transverse dynamics under the effect of force. To a significant extent, they are defined by the three transverse arms and their carefully adapted bearings. The longitudinal movement of the wheel is largely determined by the kinematics of the longitudinal control arms and the elastic properties of the high-volume bearings. The longitudinal control arms also carry the braking torque that arises. The axle is designed with slight understeer to boost steering agility and to improve stability when braking. Because its configuration is almost neutral, it offers very good straight-running properties even on very uneven road surfaces.
The longitudinal control arm mount is attached at the highest possible point. This high position of the bearing not only produces a pronounced anti-dive effect but also optimises tyre comfort. The steering performance of the axle also has a stabilising influence when longitudinal forces are applied: There’s a slight toe-in effect during braking. As a result, the tendency of the car to veer when braking on corners is reduced.
Neutral even when laden – with four-link suspension: The steering effect of the axle is designed to be unaffected by the load in the car. Although the requirements differ depending on the loading condition, it has been possible to achieve the best possible response thanks to the ingenious kinematic or elastokinematic properties: A slight toe-in on the outer wheel promotes agile and stable driving when the load is light. Increased toe-in at higher load ensures the highest level of driving stability is achieved. The high transverse rigidity of the axle combined with its tendency to understeer in response to lateral forces when the car is laden represent the optimum basis for high driving stability. Taken together with the 4MOTION drive, this amounts to a new dimension in active safety in this area.
Range of Golf Models
With the 4MOTION models, there are now 98 Golf versions available
With the introduction of the new 4MOTION all-wheel drive models, the Golf is now available in 98 versions.According to the principle of “As you like it”, this enormous choice spans nine engines, four gearboxes, two bodies, three equipment levels and two driveline versions.
The fifth generation of the Golf is available in a huge number of different models.The table of available combinations reflects the widely varied requirements of Golf drivers.By taking the 98 possible basic versions and factoring in the 171 different options in terms of paint colour and interior trim, it’s possible to arrive at 16,758 different Golf creations.
Driveline variants: The Golf is a front and rear-wheel drive car all rolled into one.The standard Golf is a front-wheel drive car; the safest type of drive train as long as the drive is “only” going to two wheels.Optionally and additionally, the TDI versions with 77 kW (105 h.p.) or more and the 2.0 FSI with 110 kW (150 h.p.) can be ordered with 4MOTION all-wheel drive.A Haldex transmission unit ideally distributes the power from the high-torque turbodiesel engines to the front and rear axles.Other than the Audi A3, there’s currently no other directly competing model in the same class that’s available with all-wheel drive.
Gearbox variants: The Golf has a six-speed gearbox as standard in all models with 85 kW (115 h.p.) or more.However, the trend towards six forward speeds is not just confined to the manual boxes.Both automatic gearboxes used in the Golf have six speeds as well.Petrol-engined models with 75 kW (102 h.p.) or more use a highly modern automatic with a torque converter lock-up clutch.The automatic gearbox in the TDI versions with 77 kW (105 h.p.) or more does not have a lock-up clutch and is probably the fastest and crispest automatic gearbox in the world at present. It’s called the Direct Shift Gearbox (DSG) – a technology that will also set the new Bugatti Veyron apart from the crowd.
Engine variants: As at July 2004, the new generation Golf is available with five petrol and four diesel engines (all Euro 4-compliant).The power ratings range from 55 kW (75 h.p., petrol and diesel) to 110 kW (150 h.p.).All the diesels have direct injection.The 66 kW (90 h.p.), 85 kW (115 h.p.) and 110 kW (150 h.p.) petrol engines are also supplied with fuel via direct injection (FSI).Incidentally, the best-selling engine is the 1.9 TDI with 77 kW (105 h.p.).
Equipment variants: The new Golf does not have a basic equipment level in the classic sense.Even the “Trendline” version offers safety, comfort and fun across the board.”Comfortline” and “Sportline” offer exactly what they say they do: the former concentrating fully on comfort and the latter fully on sportiness.The three lines are different in character, but resemble one another in terms of safety:Every new Golf comes with six airbags, ESP, active front headrests, three-point seatbelts on all five seats and a body structure that scored a five-star rating in the Euro-NCAP crash test.
|For more discussion on this story, click on the link to our discussion forums to the left.|