Rover P6 engineering

In all considerations, the Rover 2000 has to be one of the best engineered cars in the whole wide world. From basic structural concepts to provisions for passenger comfort and safety, it ranks head and shoulders above the ordinary, the mundane and the mass-produced. The Rover 2000, it would seem, is a custom-designed sports sedan, manufactured in quality.

The term "sports sedan" lends the key to understanding why the 2000 is as it is. The chassis/body/powertrain concept is more that of an out-and-out sports car than it is that of a multi-passenger family sedan. In fact, the Rover´s chassis and suspension probably are far more exotic than most similarly-priced sports cars. If it weren´t for the fact that the 2000 has four doors, it could successfully be called a sports car.

The sports car attitude begins at the ground, where Rover shoes its 2000 series cars with radial-ply tires. No messing around with excuses about how suspensions are incompatible with such harshness-production tires; Rover just up and equips the car with the best kind of tires for all-around driving. There´s no problem with suspension because that is designed in harmony with the tires. Of course, Rover uses 165-14 Dunlop SP 41 radials, and places them on 14 x 5-in. rims. Why radials? Longer wear, as much as three times longer, even under "enthusiastic" driving conditions, may be expected. Better steering and stopping responses are insured, whether the roadway traveled is wet or dry. And better fuel economy is gained because the radials have less rolling resistance than do similar-sized conventional ply-tires.

Then, for stopping, Rover lays on disc brakes at all four wheels. The discs are solid rotors with dual opposing-cylinder calipers. Where most European cars have disc-drum or all-disc systems, too, Rover goes the extra step and puts the rear discs inboard, at the differential end of the half-shafts, where size isn´t dictated by the wheel diameter and where cooling is better. Unsprung weight, i.e. wheel, tire, driveshaft etc. is thus reduced, an important factor in the design of any light, high performance vehicle. The front brakes are outboard, at the wheels, where they, too, can cool best. The handbrake on the Rover is mechanically actuated, operating on the rear wheels, and is separate from the normal braking system. The dash light which reminds the driver that his parking brake is on also is circuited to signal him when fluid becomes low in the hydraulic reservoir.

The suspension systems really boost Rover out of the sedan class. The rear is fully independent, as should be expected for this type of car, but it uses the De Dion system whereby wheel-to-pavement relationship is precisely maintained under all conditions. The De Dion tube is hollow and lightweight and extends across the chassis behind the wheels. The outboard ends of the tube curve around to form the hub-carriers. The chassis-mounted differential drives the wheels through articulated half-shafts. Wheel geometry is further maintained by Watts link leading and trailing arms. The forward arm mounts the coil spring/shock absorber unit.

As might be expected, the front suspension is just as unusual as the rear. Though the layout is in general a MacPherson strut type, it has its own Rover-inspired application. MacPherson strut front suspensions are very popular with European designers these days because they are low in weight, give good geometry without a lot of ironwork projecting here or there and are reasonably economical to build. The major flaw in the MacPherson concept is that it requires an inordinately high fender line because the long strut carries its coil spring at the upper end. It also tends to raise the roll center higher than some designers like. Rover engineers and stylists got together and developed a new system. The MacPherson´s lower A-arm and long strut were retained, for their light unsprung weight, but the coil spring was moved back to the firewall where it is compressed by means of a bell--crank off the strut. This transfers some major loads off the front fender and substructure sheet metal to the firewall/cowl area which, in unit body construction, is the strongest portion of the car. An anti-roll stabilizer bar is also incorporated at the upper end of the suspension, for lessened body lean during cornering maneuvers. The steering system is worm and roller, with the gearbox also mounted on the firewall. The resulting short steering column shaft precludes the necessity for the collapsing device now included on most other cars sold in the U.S.

In all, the front sheetmetal of the Rover 2000 is particularly well designed for passenger protection as well as for good looks. There are no extra rigid members necessary in its construction, and in crash situations the Rover front end will crumple predictably rearward, absorbing the kinetic energy of the impact. The firewall bulkhead is even designed to deflect the engine unit downward in the event of a head-on collision instead of directly into the passenger compartment.

The body itself is unitized as this gives the most strength with the least weight. The cowl-to-rear seat back portion is the strongest, for optimum passenger protection, with the front and rear ends "softer" for impact absorption. The fuel tank location is integral with the body design, being located behind a steel bulkhead behind the back seat and over the differential. This keeps the tank out of the rear fenders and out from under the trunk floor, both areas highly susceptible to damage and subsequent tank rupture during impact deformation.

The safety/protection theme is carried throughout the car, though the Rover´s best sales feature is the fact that the car is so overdesigned that the ordinary driver cannot possibly get into trouble from overdriving. It is completely forgiving in its handling characteristics simply because it is so well designed. A safe car, we maintain, is one capable of being driven safely, no matter what the conditions are, and the Rover 2000 certainly falls in that category.

The interior design reflects thoughtfulness toward its customers. Seats are contoured for optimum driving and riding comfort for four good-sized adults. The front seat backs are infinitely adjustable for rake through a friction-locking device that also prevents their forward fall on hard deceleration or impact. The seat backs also are padded for protection. Arm rests and visors are padded, too, and the normal glovebox is supplanted by two huge bin-type lockers which tilt out of the dash to contain all the odd paraphernalia of family driving. The shift lever for either the manual or automatic transmission is located on the driveshaft tunnel console, and this console extends forward and upward to house the radio and controls. Padding here is a bit sparse.

The instrument panel has the look of careful design with the speedometer placed as high and far away from the driver´s eyes as is possible. Why? Shifting the eyes from road to speedometer calls for refocusing, and the task is made quicker and easier by the more distant speedo face. Controls and switches are laid out horizontally across the face of the dash and these projections, we feel, need better protection and/or location to prevent passengers from being pitched into them on impact. This is academic if the fine shoulder harness is used.

The basic power of the Rover 2000 comes from an upright, water-cooled four-cylinder engine of 1978 cc (120.7 cu.in.) displacement. The overhead camshaft power plant has perfectly "square" dimensions with a bore and stroke of 86 mm each. This gives it fairly high-revving capabilities, and its 99 horsepower peak comes at 5000 rpm. The twin-caburetor TC version, which also has higher compression and a hotter camshaft, boasts 124 bhp at 5500 rpm. Both engines utilize side-draft SU carburetors. The overhead cam is internally chain-driven and lubricated by engine oil.

Rover offers two transmissions with the 2000, one for the 2000 TC. The standard unit is a four-speed all-synchromesh manual-shift transmission which carries ratios of 3.63, 2.13, 1.39 and 1.00:1. The optional transmission is automatic, available only on the 2000, and is an adaptation of the Borg-Warner-three-speed. This has a torque converter with three forward speeds in a planetary gearbox. Naturally, the automatic gives up a bit on performance to the four-speed, but makes up for it in convenience.

Final drive for the Rover 2000 is 3.54:1 which with the 165-14 tires gives the car some 19.5 mph for every 1000 engine revs. This is just a bit short-geared for a car with such high potential cruising ability, producing 3600 rpm at 70 mph freeway travel. The engine is stout, with main bearings between each crank throw, and is fully capable of coping with such speeds without undue stress.

The best summation we can give on the Rover 2000´s engineering qualities is to repeat the remark we overheard at a press showing. A noted German car fancier was examining the 2000 and lapping up its mechanical sophistication, when he turned to a friend and said: "It looks like it was designed at Mercedes Benz!"

ROAD TEST / USA June 1968

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