Development StoryThe development story of the Rover P5 (3 Litre) and P5B (3.5 Litre)...
Rover P5 (3 Litre) and P5B (3.5 Litre) Development Story. In the aftermath of the Second World War, Rover were riding-high on the success of the P4 and Land Rover (below), under the leadership of Spencer Wilks, with technical matters under the management of his brother, Maurice Wilks. Sales of the Land Rover in particular had far exceeded Rover’s expectations, providing the company with the funds to spend on expansion and development of advanced new cars.
Rover P5 and P5B Development
So, in the early 1950’s, Rover started to plan for the replacement of the P4 with the P5, which was specified to be lighter and cheaper to produce, and would be the first Rover with monocoque construction. It was hoped that the new car would sell for around £650. The design progressed with distinctly trans-atlantic influences, including an integral sun-shield over the windscreen, and a distinct kick above the front of the rear arches that echoed the P4. The monocoque design, with unstressed outer panels that bolted on, allowed a much lower floor which in turn allowed a much more streamlined overall design. The front suspension was to be torsion-bar and double wishbone, and the rear suspension was to be independent, with 4-wheel disc brakes planned – unheard of in the early 1950’s. Rover was also designing a V6 engine for the car, but development problems meant this engine was ultimately abandoned. As can be seen in the image below from 1954, the new car was to be quite a dramatic change from the upright and sober P4, reflecting Rovers growing confidence.
Rover P5 Mk IA
In October 1961 the Mk IA was introduced. This featured a great many detail improvements that were prompted by customer feedback and Rovers own testing, some of which was completed with Pressed Steel who produced the bodyshell. Items such as bumper mountings, boot sealing, heater and wiring harness. Body-wise the main change was the addition of front quaterlight windows. Mechanically, Hydrosteer power steering was added as an option to overcome the heavy standard setup.
Rover P5 Mk II
October 1962 saw the Mk II being introduced, with slightly more power from a new induction arrangement and a new head design (the Weslake head, named after it’s designer Harry Weslake whom Rover had asked to help with the engine improvements). This gave a welcome 16% improvement in power. Mk II cars also featured slightly revised suspension – it was lowered by around 1 inch, damping was adjusted and Polyurethane discs were added between the rear spring leafs to reduce friction and improve the ride. The interior was also improved with a slightly redesigned dashboard. The Coupe was finally launched at this time, with a 2 inch lower roofline and more raked rear screen, adding some glamour to the range for an extra £200, for which the buyer got standard power steering and additional instruments in the form of a rev counter, with other dials (Oil Pressure, Ammeter, Water Temperature and Fuel Gauge) being separated and slung under the main binnacle. There are actually numerous detail differences between the Saloon and Coupe as well (door locks, door trims, rear seat) although these were only obvious in a side-by-side comparison.
Rover P5 Mk III
October 1965 and the Mk III was introduced at the Motor Show, with more power again, a new Borg Warner Type 35 automatic gearbox, a change to negative earth electrical system, new front seats, an improved front tool tray that doubled-up as a picnic table, rear cup holders (in 1965!) in the centre arm rest, and a rear heater with separate control for rear seat passengers. Externally there was a revised grille, and a slightly revised side-trim which went all the way forwards to the front indicator, rather than stopping above the front wheel.
Finally, and most dramatically, the P5B was introduced at the British Motor Show in September 1967, featuring an all-new 3.5 litre V8 engine. The engine design had been purchased from Buick in the US, who were turning away from aluminium engine blocks back to steel, and had no need for the engine. Rover took the design and made many changes, and in the process created a classic engine that would go on to long-outlive the P5B. The new engine gave the P5B much improved performance, whilst also improving fuel consumption figures slightly. It gave Rover the opportunity to compete at a higher level, and gave a welcome bump to the P5’s decreasing sales. Aside from the new engine, there were other fairly significant changes: the front now sported two additional fog lamps below the headlamps, creating an even-more imposing front end, the car featured prominent ‘3.5 litre’ badging, and wheels were now chromed Rostyle, which many people thought were ‘a bit too much’ for a Rover, but for Rover were an inexpensive way to modernise the styling. Internally there was a large centre console housing additional switches for the fog lamps and heated rear window (when fitted) and a large ashtray. The Borg Warner BW35 automatic gearbox was standard. Both Saloon and Coupe were updated in the same way.
Rover P5 and P5B: The Complete Story
If you only buy one book about the Rover P5 and P5B, this is it. A full history on the development and life of each model, with incredible detail on the often minor changes through the models life. Rare photos are used throughout, and overall this book is well worth adding to your collection.
Rover 3 & 3.5 Litre Workshop Manual
Any owner of a P5 or P5B should buy this workshop manual. A reprint of the original Rover factory manual, this provides an in-depth guide to maintaining the P5 and P5B, from changing a bulb to rebuilding the engine. The level of detail is truly impressive, and it really is a must-have for any owner.