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William Kimberley test drives the new Land Rover Discovery 3
The Land Rover Discovery does have a fan base, but it is one that is fairly thin on the ground. A fairly practical vehicle that hovered somewhere between a utilitarian workhorse and a respectable off-roader for the urban driver, it let a lot of people down with its poor build quality and niggling faults. However, with the new version, the Discovery 3, Land Rover hopes to set the record straight and start afresh.

There is no question that the Discovery 3 has a presence on the road – its overall bulk is reinforced by the slab-sided doors and the height of the bonnet. The real points of interest, though, are to be found inside and under the vehicle.

The Integrated Body-frame – a term that has been trademarked by Land Rover – architecture, is a stiff but lightweight frame that is attached to a resistant body structure incorporating the latest high-strength steels. The result, says Land Rover, is a car with precise road manners and “outstanding” off-road composure due to the vehicle being very taut and well balanced.

Rarely used in vehicle design, Land Rover has resorted to hydroforming to put the complex shape into production, the frame being specifically developed from the concept stage to incorporate hydroformed components. The process allows for single large components that would otherwise have to be made from multiple stampings to be produced to tight tolerances.

Attention to detail in designing the frame has led to a number of interesting features such as the rear drive shafts passing through the chassis frame rather than causing a “swan’s neck” as seen on other designs. Not only does this help keep the overall height of the vehicle in check, but also serves to protect the shafts when the car is being driven off-road. The end result is a frame that is structurally more efficient than a conventional chassis, being lighter in weight and providing a stable foundation for the new all-independent suspension.

The Discovery 3 uses double wishbones at both the front and rear with special attention being paid to the locating bushes that have been selected to provide the optimum balance between ride, handling and isolation properties. The entry-level models feature coil spring suspension while electronically controlled air suspension is found on all other versions. The use of smaller springs on the latter allows for more interior space for a third row of seats, making it a genuine seven-seater.

As with the Range Rover, the Discovery 3 features transverse cross-linking of the air springs in which air displaced by the upward movement of an air spring is transferred to the spring on the other side of the vehicle, forcing it down. The result is maximum ground contact by giving a level of articulation previously only achieved by beam axles. During normal driving, though, the cross-linking is automatically deactivated.

When it comes to stopping the vehicle, there are two different systems being used by Land Rover, although both feature ventilated discs all-round, with large, twin-pot sliding callipers on the front axle and single-pot callipers on the rear. The difference is that the V8 petrol version uses larger discs than those found on the TDV6 and V6 petrol models.

ABS is standard across the range as is Hill Descent Control, Electronic Traction Control and Dynamic Stability Control. Electronic Brakeforce Distribution is also incorporated to provide optimum braking regardless of the vehicle’s load. A first for Land Rover is the Electronic Park Brake that acts on a 210 mm drum incorporated in the rear brake discs.

The body structure itself is similar to that of a conventional welded monocoque assembly with two monosides, floor, roof and bulkheads. Each monoside assembly is contructed from a single large outer pressing that extends from the ‘A’ to the ‘D’ pillars and incorporates the sills and cant rails. The rear side window aperture is designed to mount the glazing that extends into the roof as a design feature replicating the outline of earlier Discovery models.

The outer pressings are reinforced by separate internal components. Some of these are pressed in high-strength steel while boron steel – which makes up two per cent of the total body weight by structure – is used for the integrated ‘A’ pillar front cant rail reinforcing member and for the ‘B’ pillar reinforcement. The bodyside structure also houses the curtain airbags.

The floor structure consists of three large pressings for the front, intermediate and rear floor areas with separate cross-member, reinforcement and mountings for the seats. The roof is braced by cross-members to preserve body strength and rigidity when the roof-glazing is fitted. The roof assembly includes reinforcement for the front header panel which helps to form the ‘safety cage’ of the vehicle. The two-piece tailgate, doors, ‘clamshell’ bonnet and front wings are separate, bolt-on assemblies.

When it comes to the powertrain, there is a choice of three different ‘V’ configurations: the TDV6 2.7 litre diesel for Europe and other selected markets, the V6 4.0 litre petrol engine for selected markets and the V8 4.4 litre petrol engine.

The common-rail diesel engine with piezo injection is the highly acclaimed one that made its debut in the Jaguar S-Type. It develops 190 ps (140 kW) at 4,000 rpm and produces 440 Nm (325 lb ft) of torque at 1,900 rpm. By using compacted graphite iron (CGI) for the block has enabled it to have a power-to-weight ratio of 1.32 kW per kg. The forged steel crankshaft is carried in four main bearings that are each cross-bolted with six bolts to provide a solid mounting and to control high-frequency vibrations. The crank is further supported by an aluminium ladder-frame attached to the bottom of the crankcase. The high-pressure die-cast frame is unique to the Land Rover installation in order to provide continuous lubrication at high-tilt angles. It incorporates baffle plates to prevent foaming of the lubricating oil and, being secured to the block by 18 bolts, creates a stiff, compact and lightweight bottom-end structure. Attached to the ladder-frame is a pressed-steel sump, again unique to the Land Rover installation. The oil pick-up optimises its operation at the acute angles encountered in off-road driving. Unlike the Jaguar engine, only there is only one turbocharger, a fully sealed unit to suit Land Rover wading requirements.

The 60 degree, 4.0 litre V6 petrol engine is used in a number of Ford sports-utility vehicles as well as the 2005 Mustang, but it has been extensively developed for Land Rover. In the Discovery 3, it produces 215 ps (161 kW) at 4,500 rpm and 360 Nm (265 lb ft) of torque at 3,000 rpm. Modifications have been made to the pressed-steel sump to suit the Land Rover installation, including a new oil pick-up pipe to ensure lubricant flow at acute off-road angles.

The alternator, air conditioning compressor and the power steering pump are all unique to the Land Rover installation and are mounted as high as possible to protect them in deep wading conditions. A new, electronically-controlled variable tract inlet that has been developed for the Discovery 3 is a major contributor to the improvement in power and torque delivery.

Other changes unique to Land Rover are a new, double-lip oil seal and slinger at the front end of the crankshaft to cope with Land Rover wading requirements while the engine is fitted with a new, Land Rover-branded acoustic cover.

The V8 also derives from Jaguar but with a slightly increased bore that sees is stretch from 4.2 to 4.4 litres. This increase in capacity, together with a new engine management system, sees the engine produce 295 ps (220 kW) at 5,500 rpm and 425 Nm (315 lb ft) at 4,000 rpm.

As with the V6 petrol, the sump has been re-designed to ensure lubricant delivery at all angles of operation while the oil capacity has been increased by 18 per cent, from 6.8 litres to 8.0 litres compared with the Jaguar engine. The oil pump has been completely re-designed with simplified porting resulting in improved lubricant delivery and the use of a pressure relief valve, replacing the over-pressure valve on the Jaguar engine. The modified pump is more efficient and takes less power from the engine. The front crank oil seal has also been modified with an additional sealing bead to meet static wading requirements while a mud and slurry finger and labyrinth have been added to prevent contamination. Engine ancillaries have been positioned as high as possible to avoid damage during wading and there is a new acoustic cover.

A six-speed gearbox is available with the TDV6 diesel engine only, the ZF-6S-53 unit having a unique case to suit Land Rover requirements. ZF also supplies the six-speed automatic transmission that is specified for all petrol versions and is optional on diesel engine models. 30 kg has been saved in a new transfer box.

Being an off-roader, the Discovery 3’s off-highway performance is highly important and benefits by being the first model to feature Land Rover’s Terrain Response system. This automatically selects the optimum settings for the vehicle’s dynamic control systems over a variety of on-road and off-road driving conditions at the twist of a chunky rotary switch mounted on the centre console.

It controls various key sub-systems such as the electronic management system (EMS), the automatic gearbox function, the electronically controlled centre and rear differentials and the four-corner air suspension. Critical to its overall performance is its relationship with ABS, Electronic Traction Control, Dynamic Stability Control (DSC), Hill Descent Control and, new for the Discovery 3, the electronically controlled centre and rear differentials.

The selection of Terrain Response alters the throttle map within the EMS to provide a different amount of torque for a given amount of pedal travel and a revised sensitivity of torque delivery from the action of the throttle pedal. This effect improves driveability and optimises the engine’s response to given terrain. In slippery conditions it gives a softer torque delivery while a more aggressive response is provided for sand driving. The gearchange points in the 6-speed automatic gearbox are also selected to suit the surface.

The electronically controlled centre differential and the optional slave rear differential are controlled by the Terrain Response for improved traction and vehicle composure on difficult surfaces while it can override the DSC in certain off-road circumstances.

With such demands on the vehicle’s electronics systems, Land Rover has paid a great deal of attention in this area resulting in there being four main elements to the electrical system. There are grouped depending on the speed of the transmission required and compromise a high-speed HS-CAN, medium sped MS-CAN, lower speed LIN-bus and a MOST – Media Orientated System Transport – network. The use of integrated networks means that data can be shared by broadcasting around all the vehicle systems so that the driver, for example, can be fed with information to the driver display from the chassis control units by using the HS-CAN, MS-CAN and MOST systems.

Altogether, this new Discovery represents a considerable leap forward for the model. It sets out to do what Land Rover is traditionally good at – engineering off-road vehicles – while remembering that so many of them never get further than mounting a kerb, so good road manners are essential. What could not be assessed in this review was the build quality which blighted the old model, but assuming that these have been put right, the Discovery 3 should help Land Rover assume its once-dominant position in the 4x4 world.