Rover P5/P5B (1958 – 1973) Review

June 1952

First work began on the P5 project

A mock-up of the small Rover P5 project of 1952-1954. No running prototypes were made.

The Rover P5 story started in the early 1950s, but the car then visualised turned out to be very different from the one that was launched in 1958. Maurice Wilks has envisaged the car as a ‘light P4′ with, what was called, ‘floor-cum-chassis construction’. Other requirements were that it had to be as well-built, and as refined as previous-generation Rovers. Also, that it had to be cheaper to buy – at around £650 – and to manage 30mpg. To achieve these goals, it was felt that the car’s weight had to be kept down to 22cwt – and Gordon Bashford, working alongside Robert Boyle, worked on a monocoque base unit design to realise this.

The structure, which was hoped would be rigid enough to accept open coachwork, was to be designed as a single unit with all inner panels such as the floor, front and rear bulkhead and door post stressed. The outer panels, which would be completely non-stressed skins, were to be simply bolted on. And like the P4, the doors, bonnet and bootlid would be made of alloy.

This project was Rover’s first attempt at a monocoque design, and as Gordon Bashford later explained: ‘There was no computer aided design in those days, of course, so all the stress engineering had to be done by mathematical dexterity and testing, particularly pave testing.’ The wheelbase of the car was originally set at 103-inches compared with the P4′s 111-inches, but did vary at the whims of Rover’s marketing department.

May 1955, and the P5′s really starting to take shape now (above and below).

The Rover P5 was a product of free-thinking, and among the advanced concepts used in the design were independent rear suspension and four-wheel Lockheed disc brakes. During this period, Gordon Bashford became responsible for Rover’s forward planning, and devised some amazing alternative P5 concepts – including front wheel drive, rear engines, de Dion-axled cars, rear mounted transmissions, four wheel drive; and a car with the gearbox mounted under the seat… None of these cars progressed beyond the drawing board; although some of the ideas did find their way into the later P6.

By the mid-1950s, enthusiasm for the small P5 was waning. Such a car had the potential to be a big seller, but at the time, Rover would have had difficulty finding the space at Solihull factory to manufacture it. The authorities had denied the company planning permission to expand; a situation unimaginable today. So the company was forced to rethink. It was decided that as a high volume, low profit car was out of the question, a low volume, high profit prestige car to compete with the likes of the Jaguar MK VII would need to be developed instead.

September 1955

Rover P5 project grown to become the firm's large new flagship

With this, the P5 began to put on weight and grow larger. The wheelbase expanded to 108-inches, then 110.5-inches. The width grew to 70-inches, while it put on weight up to 27cwt. An element of cost control came into play, and the suspension system was revised to incorporate an ordinary beam axle at the rear – but the twin wishbones and laminated torsion bar at the front remained.

Frontal styling seems fixed by September 1955.

The car also had a box-section front subframe, which carried the suspension, steering, engine and gearbox. This was attached to the rest of the vehicle by six rubber bushes, and although it was complex, Gordon Bashford thought there were benefits in terms of servicing (it could be dropped from the car for easy access) and refinement, he later revised his opinion. The reason for this change of heart was that the subframe added excess weight.

The man credited with styling the Rover P5 is David Bache who had arrived at Solihull in 1953. His first attempt at the P5 design resulted in a low-slung sports saloon, and as expected, met with the disapproval of Maurice Wilks. Bache’s first major styling exercise had been to create a revised Rover P4, and many of the styling cues he chose for the P4 proposal ended up being carried straight over onto the P5.

April 1957

P5 styling finalised

April 1957, and the styling is complete. Note the Road Rover model in the background.

Once the saloon had been completed, Bache also designed a Coupé version of the P5, although that didn’t appear until 1962. In prototype form, it was certainly interesting, as it did without a central door pillar and featured frameless side windows. However, problems of excess wind noise during the development, and the fact that the Coupé bodyshell wasn’t as stiff as the saloon’s led to the reinstatement of the B-pillar – and the elegantly slim-framed doors for the production version.

In terms of powering the P5, the original plan of introducing it with a new engine were soon put on hold. The V6 had been axed (because of costs and production issues), and Rover decided that enlarging its existing 2.6-litre inlet-over-exhaust inline-six would be a far more expedient option. The man charged with this task was Jack Swaine, who later recalled: ‘At the time, the inline six was a 2.6, and unless we Siamesed the bore, we couldn’t increase the capacity with the bore sizes that existed. So, we shifted the bore centres again, and were able to do this by by making it a seven bearing engine. We had the two intermediate bearings on the four-bearing engine, and we could use narrower bearings by going to seven, and shuffled the bore centres along the length of the block in effect.’

All this work resulted in an engine capacite of 2995cc. Roller-type cam followers were fitted to improve breathing, and the enlarged power unit produced 115bhp gross (105bhp net) at 4500rpm, and the torque figure was a stately 164lb ft at 1500rpm.

October 1958

Rover P5 launched

Launched in 1958, the Rover P5 made quite a splash

The Rover P5 saloon was unveiled at the 1958 Earls Court Motor Show, and was generally well received. Although once road testers got their hands on it, there were criticisms of its sub-standard noise suppression as well as the notchy gearchange – closely derived from the P4. The P5′s weight had now ballooned to 32cwt, so performance testing realised some unimpressive figures – a top speed of 96mph, with 0-60mph covered in a yawning 16.2 seconds.

Steering was a little on the heavy side, too, although this was rectified in 1961 with the arrival of the Mk1a, which had the the option of a Hydrasteer power assisted set-up. And despite the simple rear suspension, the ride was was universally praised.

August 1959

First improvements introduced

The P5 sold well to the older driver, but Rover was keen to distance itself from this gentlemanly image, and constantly modernised it throughout its production career. The improvements arrived rather soon after launch, in August 1959, putting right many of the original car’s wrongs. Front disc brakes were fitted (making stopping a less stressful affair), and the engine was revised – an impressive new version of the 3-litre engine finally meant that the P5 had enough power to top 100mph; all thanks to the technical input from Harry Weslake.

August 1961

Launch of Rover P5 Mk1a

In 1961, the Mk1a, with that power steering upgrade appeared.

August 1962

Rover P5 Mk2 launched

It was at this point that the memorably handsome Coupé version was unveiled, adding an element of glamour to the previously upright P5. There was a premium, though – the Mk2 weighed in at an extra £200, although the buyer had the advantage of standard power steering (it was previously optional), a rev counter and four additional gauges on the already well-stocked dashboard.

However the 3-litre inlet-over-exhaust was at the limit of its development – as smooth as it was – and it’s unlikely that the P5 would have survived much beyond 1967 in that form. Rover had previously looked at replacing it with both five- and six-cylinder versions of the P6 2000′s engine, before that fabled chance encounter between the company’s managing director, William Martin-Hurst, and a discarded engine at a boatyard in 1963…

January 1964

Rover 'discovered' the Buiok V8

Hurst allegedly ‘discovered’ the light alloy 3528cc engine at Mercury Marine in Wisconsin quite by chance – previously, the all-aluminium engine had powered the Buick-Oldsmobile Y-Body ‘senior compact cars’, and had been turbocharged to produce over 200bhp. However, the power unit, known as the Buick 215, was destined for a short life Stateside – being dropped from the GM range in 1963 (it was launched in 1960, and had suffered cooling problems in use) after the US car manufacturers returned to cast iron for its engines (improved casting techniques and thin wall construction lessened the weight penalty), following concerted pressure from the American steel industry.

Legend has it that Hurst measured the engine, and decided to have it there and then, although in reality it’s more likely that Rover management was already well aware of the power unit. In January 1964, Rover’s US operations management, J Bruce McWilliams, had been tasked with finding a possible replacement for the P5′s engine. McWilliams was visiting Mercury Marine, continuing talks about the possible sale of Rover Gas Turbines to the company, and discussions turned to the possible use of the Buick 215. He realised that it was the ideal replacement for the inlet-over-exhaust engine – both light, compact and smooth, and after discussing the possibility of using it with Martin-Hurst, decided to approach GM, and campaign to release it to the British company.

By January 1965, a reluctant GM had sold the tooling for the Buick 215 to Rover, and the process of productionising the power unit at Solihull began. Retiring Buick engineer Joe Turley moved to the UK to act as a consultant, and a rapid development programme to modify the P5 to accept it ensued. Because the Buick 215 was all-alloy, it was a whopping 200lb lighter than the P5′s six cylinder; and a mere 12lb heavier than the P6′s four-cylinder unit. It was a win-win situation.

The P5 was the first Rover to use the V8, and as the car had a wide engine bay, it presented few problems to the engineers. Gordon Bashford later recalled, ‘As far as I can remember, the first P5 V8 was just a cut-and-shut job in the experimental shop. It was just a question of slipping the engine and removing any protuberances.’

The engine was revised for European tastes, as it was not designed to rev beyond 4400rpm, and featured improved manifolding with twin SU carburettors and improved rocker shafts. When installed in the P5, its power output was a generous 160bhp (net) at 5200rpm, and peak torque jumped to 210lb ft at 2600rpm – a considerable improvement on the 3-litre inlet-over-exhaust engine. Rover’s only gearbox able to cope with all this power and torque, was the automatic Borg-Warner Type 35.

October 1967

Rover P5B launched

The Rover P5B was introduced in the autumn of 1967 and ushered in a revised styling package. The saloon verison cost £1999, while the Coupé came in at £2097 – an increase of £60 over the ougoing 3-litre P5, and superb value for money. The sluggish P5 had been transformed into the fast P5B. Top speed was now 110mph and the 0-60mph time had been but to 11.7 seconds. There was no cost at the pumps, though, as fuel consumption remained unchanged over the outgoing model.

Motor magazine summed up the P5B Coupé in its 1967 road test quite succinctly. ‘The Rover is so well insulated from all sources of noise that a Jeeves-like calm nearly always prevails; even when the engine is at its most discreetly agitated, it emits nothing more than a purposeful hum. Most of the time the engine merely whispers the car along with the proverbial turbine like smoothness characteristic of good V8′s.’

With a lighter engine, the P5′s handling was massively improved, and Rover now possessed a formidable sporting saloon with which to fight the opposition at Jaguar and Mercedes-Benz. Rover had envisaged a production rate of 85 cars per week, but this was soon doubled in order to satisfy orders. The P5B soon became a favourite with government officials, and every Prime Minister from Harold Wilson to Margaret Thatcher used one.

P5 in its most desirable form – V8 powered with the Coupé bodyshell.

June 1973

Rover P5 ceased production

Unfortunately for Rover, Leyland then agreed to the merger with British Motor Holdings in 1968, to form the British Leyland Motor Corporation. The formation of this super-company brought Rover within the same stable as Jaguar, and as related in the P8 development story , after the P5B ceased production on the 22 June 1973, Solihull was forced to withdraw from this profitable sector of the market, making way for Jaguar.