Four Models of Range Rover Engineering

The Range Rover is Now in its fourth generation, but the latest model is very different to its predecessor of 50 years ago. Range Rover World looks back at the engineering behind the model.

THE FIRST GENERATION AND ‘CLASSIC’ RANGE ROVER

Four Models of Range Rover EngineeringThe Range Rover started out as an incremental Land-Rover model, but its architecture was very different from its 1940s stablemate. Given a free hand in its development, the team led by Charles Spencer ‘Spen’ King came up with a vehicle that was dramatically advanced for its time with permanent 4-wheel drive and powerful V8 engines being in true supercar territory.

The chassis was a radical departure from the fabricated box-section of the Land-Rover. The longitudinal members were incredibly strong being formed from interlocking ‘C’ section pressings welded together. The considerable investment required more than paid for it self with the same basic chassis being retained until the model’s demise and then being continued in the Land Rover Discovery. The basic construction, albeit with a deeper section, was fitted to the Land Rover One Ten of 1983 which continued as the Defender until 2016.

While using similar beam axles as the Land-Rover, the Range Rover featured long-travel coil spring suspension, the front axle being located by leading radius arms, popularly known as ‘C Spanners’ from their shape, the set-up being inspired by examining the contemporary Ford Bronco. The rear axle was located by an A-frame that incorporated the mounting for a Boge self-levelling unit. The front springs were coaxial with the dampers while the rear dampers were separate, the right-hand facing rearwards with the left facing forwards to prevent axle tramp.

The coil springs endowed the Range Rover with superlative articulation for an unrivalled off-road performance as well as more refined highway manners compared with a Land Rover. Although it remained stable, this was at the expense of considerable body lean, a characteristic later ameliorated by the fitment of an anti-roll bar.

Among the Range Rover’s safety features were a dual-line braking system with disc brakes all round and an AC Delco collapsible steering column.

The driveline comprised the Rover 3.5-litre V8 fitted with low compression pistons and other modifications to suit the Range Rover’s intended usage. The 4-speed gearbox was integrated with the transfer box which had high and low range gearing and a centre differential, early models have a limited slip device with manual locking which was soon replaced with a simple locking system.

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The body consisted of a steel sub structure which incorporated the inner front wings. The floor comprised several steel pressings including the deep tunnel cover. The bonnet and lower tailgate were also steel. Other panels were aluminium. As with the chassis, this structure served the company well, being used on the later Discovery and slated for a 1990s Defender replacement.

As the model developed, the chassis was stretched 8 inches (200mm) for the LSE model which also introduced air suspension. The driveline was also progressively improved with more powerful engines, later including fuel injected and capacity increases. Diesel models were also introduced, first using a bought-out VM unit and later the in-house Tdi. Automatic transmission was also offered, early models using a Chrysler 3-speed gearbox, later with a ZF 4-speed. A 5-speed manual gearbox with separate transfer box was also offered with the latter acquiring a viscous coupled centre differential. The braking system was progressively upgraded to include ABS and traction control.

The body was progressively altered to cater for the four-door variant and again for the LSE. It also benefitted from an upgrade package as part of the Discovery programme which included a pressed steel floor. Later models were also fitted with side intrusion bars in the doors.

SECOND GENERATION RANGE ROVER (P38A)

Although the second generation Range Rover, developed under the code name P38A retained the body on frame architecture of the original, the technology behind it was very different.

The chassis was of box-section design formed from steel pressings using the latest alloys and of varying widths. It tapered inwards at the front to provide for an improved turning circle while the increased width from the mid-section rearwards added to stability as well as accommodating the spare wheel under the load space area and the air suspension reservoir.

The second generation Range Rover was equipped exclusively with variable-height air suspension which offered a variety of settings from a low ‘Access’ mode to and extended off-road height. The front axle was again located by ‘C Spanner’ radius arms, assisted by a Panhard rod. An anti-roll bar was also fitted. An innovative feature at the rear was the specification of composite radius arms combined with a Panhard rod, the arrangement giving passive rear-end steering.

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Engine choice comprised a BMW 6-cylinder, 3-litre diesel and V8 petrol engines in either 4.0-litre or 4.6-litre capacities. They drove through a 5-speed manual gearbox, which was standard on the diesel and 4.0-litre V8 derivatives or a 4-speed ZF automatic gearbox which was standard on the 4.6-litre V8 and optional on the 4.0-litre V8 and later, on the diesel. The transfer box was chain driven and used a viscous coupling to control slip between the axles. The transmission was controlled by an innovative ‘H-Gate’ arrangement.

The braking system featured ABS as standard with Electronic Traction Control as standard on the 4.6-litre, optional on other models. This originally operated on the rear wheels only but was later extended to all four wheels.

The monocoque body was a radical departure from its predecessor. The base structure was of double side zinc coated steel with only the front wing outer panels, door skins, and lower tailgate skin being in aluminium. The windscreen, rear quarter glass and tailgate glass were bonded to the structure to enhance rigidity. The body was attached to the chassis using compliant mounts to improve refinement by reducing vibration transmission into the cabin.

Four Models of Range Rover Engineering structure

The second generation Range Rover was earmarked for an early replacement, so modifications were sparse. The V8 engine received a package of refinements including a new inlet manifold and ignition system. While power output was unaffected, torque response was improved. A cast alloy sump replaced the pressed item, the change improving the engine’s refinement.

While the last second generation Range Rover left the production lines in 2001, it nearly got a second chance as the basis for the market segment later filled by the Range Rover Sport. Modifications included in the proposal included a coil spring suspension system.

THIRD GENERATION RANGE ROVER (L30/L322)

The launch of the second generation Range Rover coincided with the acquisition of the Rover Group, Land Rover’s parent company by the German car maker, BMW. Plans for a facelift including a BMW 12-cylinder petrol engine were scrapped and a new programme, code named L30, was instituted using Range Rover engineers working alongside German counterparts who were also involved with vehicles including the BMW X5 and 7-Series.

With body stiffness the key to performance and refinement, the monocoque architecture of the new generation of Range Rover offered a step change compared with previous models. The foundation structure, which incorporated the rear wings, was of zinc coated steel, also used for the upper and lower tailgate. Advanced stamping technology enabled the signature ‘clamshell’ bonnet to be pressed in aluminium, which was also used for the front wings. The doors were entirely constructed in aluminium, including the side intrusion bars, and incorporated a mixture of pressings, extrusions and castings. The suspension was mounted on steel subframes using hydroforming techniques allowing complex shapes while avoiding the need for fabrication.

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Once again, the only suspension offered utilised air springs but for this generation, it was independent all round using a MacPherson strut at the front and double wishbone at the rear. To ensure maximum articulation when off road, the springs were connected side to side, air passing through an electronically-controlled valve to mimic the action of a beam axle when conditions demanded.

The foundation ABS braking system was enhanced by an Emergency Brake Assist (EBA) feature and the adoption of the Hill Descent Control (EDC) system, first seen on the Land Rover Freelander and subsequently on other models including BMW’s XS.

Power came from a selection of BMW engines, a 6-cylinder, 3-litre diesel and a 4A4-litre V8 petrol. A 5-speed automatic transmission was offered for both engines coupled to a 2-speed chain-driven transfer box with inter-axle slip controlled by a Torsen® automatic differential. The rear differential was mounted on the sub frame while the front was attached to the engine sump.

The Ford Motor Company acquired Land Rover in 2000, shortly before the launch of the new Range Rover. This led to the specification of Ford-derived engines including a 4.2-litre V8 supercharged petrol engine. Later petrol offerings included a 5.0-litre V8 in naturally aspirated and supercharged forms. The BMW diesel was replaced with a 3.6-litre V8. The engine changes were accompanied by changes to the transmission including a 6-speed automatic gearbox with some markets later being specified with an 8-speed unit. The transfer box was fitted with an electronically controlled multi-plate clutch centre differential to enable the specification of Land Rover’s Terrain Response system.

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