A History of the Rover P4
in celebration of its 50th Anniversary 1999

By Roverdom Editor Kevin Philips

The all-new post war Rover finally materialised in 1949, designated P4. This model represented a new departure from traditional Rover design with the bonnet, wings and body no longer being considered separate entities. It consisted of a full-width body shell with straight sides and contour lines pressed into the panels. At the rear, the boot balanced the bonnet to give the new look "going both ways" appearance, the new model being loosely based on the 1947 American Studebaker.

The new car appeared in September 1949, its new and curious frontal aspect causing many a broken heart among devotees of the "classic" Rover style exemplified by the P3's and the models of the later 1930's. The P4 however was quite up-to-the-minute in styling and a car that was to create a brilliant future for the Rover Company.

The P4's chassis was a development from that of the P3 but with a fu]llength frame upswept over the rear axle. The P3's independent front suspension in its final form was retained at the front while the familiar semi-ecliptic springs took care of the rear. The steering was Burman recirculating ball-type, also from the P3. In these essentials, the P4 chassis remained unchanged for the full 15 years of its production run.

The first P4 was the Rover 75, sporting a six-cylinder engine of 2103 cc with a one-piece lightweight alurmmum cylinder head and manifold, chromium-plated cylinder bores and an external wipac oil filtration system. Twin SU carburetors were fitted and an oil bath air cleaner, the engine now giving a slight increase in power, plus greater flexibility through increased torque compared to the power plant originally fitted to the P3.

The 75 was joined in September 1953 by the four cylinder "60", developing 60 BHP from a 1997cc spread-bore engine and the six cylinder "90" developing 90 BHP from 2638cc also in a spread-bore engine. Both engines used a single SU carburetor, the 60 breathing through a conventional oil-wetted gauze air cleaner, while the 90 (and export 60's) sported a Vokes paper-element air cleaner. The 90's compression ratio was raised slightly in 1954 and again in 1955 to give it 93 BHP, which was retained until the end of its production rim in 1959.

In September 1955 for the 1956 model year, the "75" also received a spread-bore engine. This new engine developed 80 BHP from 2230cc and ran a single SU carburetor and Vokes paper element air cleaner. Export models retained the oil bath air cleaner. The spread-bore engine evolved due to the number of changes required to the basic inlet over exhaust engine design in order to create the 90 engine. The amount of over-boring

required to extract the extra 15 BHP led to siamesed cylinder bores and piston ring scuffing if the cars were driven really hard.

The answer was the spread-bore design in which the cylinder bore centres were re-positioned within the block to leave more metal between each bore and ultimately to provide better cooling.

September 1956 presented the two new models for 1957, the "lOSR" and "lOSS". Both used a high compression version of the 90 engine with twin SU carburetors developing 108 BHP.

The lO5R was available in both standard and deluxe versionS, the standard model being basically a 90 with Roverdrive automatic transmission. The higher performance engine was required to offset the loss of power soaked up by the Roverdrive transmission. The deluxe model was basically an automatic version of the high-spec 1055, but without the performance or economy.

The lO5R remained in production for the 1957 and 1958 model years with a total of only 3,540 cars being produced.

There are several theories for the early demise of the Roverdrive automatic transmission. Some cars did not perform as well as they could have, while others ran trouble-free for many years. They became a Rover agent's headache as it was a major operation to set up and adjust the control linkages correctly. The engine performance was well down compared with the other models of the P4 range and the fuel consumption of the 105R was dismal, at a time of petrol rationing after the Suez crisis of 1957.

The Roverdrive transmission had been tried during development of the new P5 Rover to give an automatic option, but it was prone to overheating when coupled to the 3 litre engine. Rover abandoned further development and settled for the Borg/Warner DC 3-speed unit for the new 3 litre.

The lO5R had not been a success for Rover. At Sohhu.U, it had been universally disliked and its acceleration was considered pathetic. Its sister however, was a totally different story. The 1055 (the "S" being for sporting) was designed as a high performance luxury saloon. Its twin carburetor 108 BHP engine gave it a cruising speed of 90 mph, its occupants travelling in total luxury. The 1055 had virtually every optional extra fitted as standard, including: twin fog-lamps, front side lamp reflectors, chrome wheel rim em.bellishers, individual front bucket seats, cigar lighter, radio, overdrive unit and foot rests for the rear seat passengers. It also had more powerful servo assisted brakes that were very efficient even at the higher cruising speeds that these cars were capable of.

The lO5R deluxe and 1055 by virtue of their high-spec fittings became the ultimate P4 with no other model being finished to such a high standard.

Indeed, all later P4's became somewhat overshadowed by the new P5 3 litre cars.

The end of 1958 saw both the lO5R and 1055 dropped and the line up for 1959 included the new P5 3 litre as well as the 60, 75, 90 and 105 models. The 105 was basically a lOSS but without the high-spec fittings unless specified; which many were. These continued until September when the entire P4 range was dropped in favour of two new models.

The two new models for 1960 were the 4 cylinder 80 and the 6 cylinder
100. The 80 was a 4 cylinder replacement for the 60 and was the only P4 not to use a variant of the inlet over exhaust engine. The new engine fitted to the 80 was an overhead valve unit of 2286cc similar to that installed in the Series 2 Landrover. This had been developed from the Landrover's diesel unit of 2052cc and developed 77 BHP and was fitted with a solex carburetor and oil bath air cleaner.

The 100 featured a new 2625cc inlet over exhaust engine which was essentially a short-stroke version of the new 3 litre engine. This latter engine had been a further development of the spread-bore 90 engine with the cylinder centres again re-positioned~ a seven-bearing crankshaft and roller cam followers in place of the original pad-type. The 100 developed 104 BHP and was fitted with a single SU carburetor and oil bath air cleaner.

The 80 and 100 were supposed to be the last of the P4 range of cars. Rover engineers had been working on the P4's replacement since 1956 and that car - the P6 or Rover 2000 - was originally scheduled to enter production in 1961.

The P6 project was delayed in 1960 due to delays in obtaining planning approval for a new assembly plant at Solihull. It soon became clear that this problem would not be settled overnight so work was temporarily suspended, eventually delaying the programme by two years. By October 1960, the decision had been made to extend the P4 programme by two years and this would require another two models being developed at minimum cost in order to achieve this.

The new models became the 95 and 110 and were introduced at the London Motor Show at Earl's Court in September 1962, alongside the new 3 litre MkII saloon and 3 litre coupe models.

The four cylinder engine was discontinued altogether with both new models being based on the 100. The 95 was broadly similar to the 100, using a slightly less powerful 102 BHP version of the six cylinder 100 engine but with a 3.9:1 rear axle and no overdrive.

The new 110 benefited from mechanical development work that had been carried out to improve the P5 3 litre. A short manifold version of the 3 litre's Weslake head was fitted to the 100 engine, increasing power from 104 to 123 BHP. This gave the 110 the highest top speed of any P4, although its acceleration was closely matched by that of the 105/1055 model.

After the introduction of the 95 and 110, design and development work on the P6 continued in earnest, with the car going into full-scale production from September 1963. It was clear the P4 was nearing the end of its production life, but what if the public didn't take to the new 2000? Had Rover learned from the public backlash when the P4 replaced the P3 back in 1949?

The very first 75's had a hydro-mechalliCal braking system but this only lasted for the first year with an all-hydraulic drum system being offered for the 1951 model year. The braking system was gradually improved with servo assistance being offered for 1956 but initially only on the 90 equipped with overdrive. Servo assisted brakes were standard on the 105R and 1055 models. From 1960 onwards, all models had servo assisted girling disc brakes on the front.

The original gear lever fitted to the 75 was a column change unit, but this was universally disliked and a floor change conversion was offered by Gethin's, the Rover distributors in Birmingham. Rover finally gave in to customer pressure and fitted a floor-mounted gear lever for the 1954 season, coinciding with the introduction of the 60 and 90 models. The long cranked handle was designed to leave legroom for a third passenger on the front bench seat and was adjustable to suit the driver's reach. This design remained unaltered to the end of the P4 production and was also fitted to the first of the P53 litre cars.

The P4 gearbox featured the Rover freewheel, but a Laycock DeNormanvi]le overdrive unit was optionally available on the 90 for the 1956 model year and on the 60 and 75 for 1957. Both the lOSS and 105 models had overdrive as standard. 1959 was the last year that freewheel was available.

The standard rear wheel axle ratio was 4.3:1 but in 1955 a rear axle ratio of 3.9:1 was fitted to the non-overdrive 90 which became quite common. The early 80 and 100 models were built without overdrive, but this was fitted as standard shortly after production began, so there were only a few 80 and 100 models built without freewheel or overdrive. The 95 had a rear axle ratio of 3.9:1 with overdrive not being an option on this model. The 110 had overdrive fitted as standard.

The basic body shape of the P4, particularly the passenger cabin, did not alter between 1949 and the end of production in 1964. Body shells were built by Pressed Steel at Cowley with door, bonnet and boot lid panels of Birmabnght aluminium alloy.

The first P4 75 had the 'Cyclops' front, consisting of a 15 bar radiator grille with chrome trimming around the headlamps and air intake grilles. The chrome trimming disappeared and the 15 bar grille was replaced by an 8 bar grille before the end of the first year of production. The 8 bar grille, while not as pleasing on the eye, was more practical and helped to solve the problem of overheating that the early cars were inflicted with.

The 'Cyclops' front on these early cars eventuated due to the lighting regulations in effect at the time in Britain. In essence, they required that the offside or driver's side headlamp should be extinguished when the lights were dipped, leaving only the nearside or kerbside headlamp to illuminate the side of the road. For some time, Rover had added a low mounted "pass lamp" that illuminated the road ahead without dazzling oncoming drivers, and it is this lamp that gave the early P4's their nickname of 'Cyclops'. Maurice Wilks had wanted to integrate this lamp within the lines of the body but it is probable that he had been influenced by the lines of the 1947 Tucker Torpedo.

The central passlamp was illegal in the USA and P4's built for the American market had a special cover fitted over this lamp. This cover had the number 75 cut-out which allowed the light to shine through which enabled the car to be identified at night.

By the end of 1951, the British lighting regulations had changed and this allowed the front end of the P4 to be updated. The new chromed grille bore a triangular grille badge similar to that of the P3 and was a classically simple yet very effective piece of design. It would remain in use on the P4 models until the end of production 1964, albeit slightly modified over the years. A version of it would also be used on the new PS model which was introduced in 1958 and eventually went out of production as a V8 engined P5B model in 1973. So distinctive was the design that it was re-introduced on cars built by the Rover Group in 1991 and today all Rover models are identified by this grille.

Small changes had also been made to the rear of the car for the 1952 model season. The small oval rear window had given way to a wider one and the number plate box was now rectangular, replacing the original square one. The overall result was that the car now looked wider and lower from behind and the spare wheel was now accessible through a flap beneath the bumper.

Two-tone paint schemes first appeared during 1953, but were limited to two; these being dark grey over light grey or dark green over light green, the upper colour covering the roof panel only.

For 1954, the home market 90 models were distinguished by a fog lamp mounted on the left-hand side of the front bumper, and by a 'Rover 90' in elegant script on the bonnet sides and boot lid. The enameled grille badges bore the appropriate model designation - "60", "75" or "90".

In 1953, Rover recruited David Bache who initially became an intepreter of chief engineer Maurice Wilk's ideas. He had worked at Austin's Longbridge plant, completing an engineering apprenticeship before moving into styling. Shortly after joining Rover, he was entrusted with the overall styling of the forthcoming PS project, with some of his ideas being tested as part of the upgrading and remodelling of the P4 range.

For the 1955 season, there were two pressing issues that had to be addressed. The first was that customers were complaining that the boot of the 1952 - 54 models was too small, and the second was that the existing rear lights needed to be modified to incorporate amber flashing direction indicators and red reflectors.

David Rache attended to these concerns in his 1955 model design which raised the boot line giving a consequential increase in luggage space. Also incorporated was a much wider wrap-around rear window and new tail lights consisting of stop/tail lamps, reflectors and amber flashing direction indicators. The front side lights were given larger lenses and became direction indicators while new side lamps were fitted to the top of the front wings, placed in chromed housings.

By the 1957 model year, the PS design was being flnalised and the front end revision for the P4 would reflect the new PS stylings. The 1957 models, introduced in September 1956 featured raised leading edges to the wings with amber indicator lamps incorporated within them. The side lamps were relocated hall-way down the wing fronts which were also restyled as part of a general tidying up of the frontal area. The 90 for 1957 had now also lost its distinguishing fog lamp.

The big news for 1957 was the release of the lO5R and loss models. These were last-minute surprise announcements on the eve of the Earls Court Motor Show in October 1956 and did not actually enter production until the end of the year. Both featured a twin carburettor, high compression version of the 90's 2.6 litre six cylinder engine with a new cylinder head that featured larger inlet valves for better breathing. The two SU carburettorS mounted on a water-heated inlet manifold fed the front three and rear three cylinders respectively, and there was a new exhaust system with larger-bore pipes than on the 90. The end result was 108 BHP at 4,250 rpm which allowed the 1055 to reach 100 km/li from a standing start in just over 15 seconds which was a very respectable performance for such a big heavy saloon in the mid-fifties.

1958 would see the production of two new models - the Series II Land Rover intended for launch in April, and the P5 3 litre saloon in September. The Suez crisis had hit sales of P4's hard during 1957 but now that petrol rationing was over, it was time to revita]ise interest for 1958. This was achieved by introducing a striking new two-tone colour split along with a wider variety of two-tone combinations with the colours being separated.

by a thin chromed strip running the full length of the car. At first this was only fitted to cars with two-tone finishes, but early in 1958 it was made standard on all cars, except that mono-tone cars lacked chrome strips on the leading edge of the front wings.

These changes did appeal to the buying public with the 1958 season being much better for Rover. Sales of all models except the 105R were up but it was becoming clear that the 105R was not proving to be the success that Rover had hoped for. There was nothing that could be done in the short term to alleviate its failings of high cost and poor performance3 and so Rover decided to withdraw it at the end of the 1958 season. This was not the end of an automatic P4 however, and there would be one last attempt to create such a car, although it did not go into production.

1958 had been the ultimate year for the P4 with the 1055 being Rover's flagship model until September, when the P5 3 litre was released. From this time on the 3 litre would always take centre stage with the P4 model range being severally reduced over the remaining years of production.

The 1959 model year brought the introduction of the new P5 3 litre and the P4 models received a facelift to underline the family resemblance. New bumpers and over-riders, together with a recessed radiator grille and new-style "Rover" nameplate, all followed the P5 pattern. At the rear a broad chromed embellisher strip was fitted above the rear number plate which made the cars appear lower and wider from behind.

The model range was now also reduced from five to four models. The 1 05R was dropped in order to protect sales of the new 3 litre with the automatic option and the 1055 was stripped of some equipment and reduced in price, again to protect sales of the new 3 litre. The lOSS now became a 105 and had lost the twin fog lamps, wheel rim embellishers, cigar lighter and individual front seats that had all been standard on the lO5S. These options however were available at extra cost.

Most cars of all models for 1959 were supplied with overdrive and this would be the last year for the traditional Rover freewheel which went out of production at the end of the season.

The 1959 model year was not very good for Rover with sales of all six -cylinder P4 models being only two-thirds of the 1958 totals. Sales of the new P5 3 litre were also disappointing, but this had got off to a slow start resulting from production difficulties. The four cylinder 60 however did much better with sales actually increasing during 1959.

September 1959 brought the next stage of P4 development which was the inevitable result of rationalisation of the Rover assembly lines.

A new petrol version of the Land Rover overhead valve four cylinder diesel engine had been available for the Series II Land Rover since April 1958 and it was this engine that would power the new P4 model that would replace the 60 and 75 models. This engine of 2.25 litres developed 77 BHP and went into a new P4 model that was designated as the 80.

The new 3 litre PS engine had been in production since the middle of 1958 and it seemed prudent to develop this new engine for a new P4 model rather than continue to produce two different six cylinder engine blocks. A new short-stroke version of the 3 litre engine was built comprising 2625cc developing 104 BHP that went into a new P4 model designated the 100. This new car replaced the 90 and 105 models, and buyers wanting the performance that had been available in the 105 were steered towards the new 3 litre PS.

Also new for the 1960 model year was girling disc brakes on the front wheels with the traditional drum brakes on the rear and the brakes on all cars were now servo assisted.

The option of overdrive had proved very popular from when it first became available and Rover decided to standardise this option on both the 80 and 100 models. This decision was made after production had started and a small number of early 80's and 100's were built without overdrive, having the 3.9:1 rear axle.

The 80 and 100 models could be distinguished from their earlier siblings by the dished wheels and recessed-centre hubcaps that were also fitted to the P5 3 litre. These models still had grille badges incorporating the model number but only the 100 carried its name in chromed script on the boot lid and bonnet sides.

As mentioned earlier, the P6 Rover 2000 was originally scheduled to enter production towards the end of 1961 which would allow for a years production of the P4 run -out models with the final P4 production being the middle of 1962. With the delay of the P6 project, new P4 models were introduced in September 1962 and there was now no longer a four cylinder model available.

The new Rover 95 was basically a de-tuned 100 developing 102 BHP offered without overdrive and a rear axle ratio of 3.9:1.

The new 110 consisted of the 100 engine but with a version of the 3 litre's Weslake head and developed 123 PHP. This model had overdrive fitted as standard and breathed through a paper element air cleaner leading to a 2 inch SU HD8 carburettor. This engine had to rev to 5000 rpm to achieve its maximum power and developed its maximum torque much further up the rev range at 3000 rpm compared to the earlier engines at 1500 to 1750 rpm.

With the development of the 110 engine, it is interesting to compare the road performance test carried out by "The Motor" motoring magazine in July 1957 for the lOSS, with the same test also carried out by "The Motor" in January 1963 for the 110. A comparison of the results shows that the lOSS was slightly quicker and also more econonucal than the 110.

Both the 95 and 110 models carried chromed model identification script names on their bonnet sides and boot lid but the grille badge was now the standard 3 litre badge so did not carry the car's model number. The 110 was also distinguished by its full size stainless steel wheel trims that had been introduced on the 1962 season Mk 1A 3 litre cars, but the 95 retained the original 100 recessed centre hubcaps with optional chrome wheel trims.

From March 1963 the Birmabright alloy panels that had formed the doors, bonnet and boot lid were replaced by heavier steel panels which added some 75 kg to the weight of the car. One theory for this is that it was considered more important to divert the supplies of alloy for the new PG which had it's bonnet and boot lid made from alloy.

The interior of the P4 remained basically the same over its fifteen-year production run, but minor changes and improvements were carried out, usually at the request of customers.

The original cars had rectangular instruments and push button interior door handles. These were changed after the first season to the conventional lever-type handles. The instrument panel was also changed for 1951, now sporting conventional circular dials with the clock repositioned centrally in a new facia rail.

The clock was now visible to the rear seat passengers as well as to those in the front, the upgrade resulting in a handsome and restrained facia panel that would be retained in its essentials for the next decade and a half.

The original hand.brake was a simple vertical lever located to the right and ahead of the driver, but this was also modified for 1951 and again for 1953 when it gained its "shepherd's crook" configuration.

The 1952 season cars gained a full circular horn ring in place of the half ring of earlier cars and an organ-type accelerator pedal now allowed more sensitive throttle control. On the dashboard, the low-fuel warning light was now replaced by a switch that gave access to a reserve supply of petrol via a solenoid valve in the fuel line. Rotary switches also replaced the earlier push-pu.U type and a more powerful heater was installed. The windscreen was now served by more powerful wipers that had an ingenious sell-parking facility.

From the start of production the bench seats had been trimmed in plain leather and this remained unchanged through the 1955 season. For 1956, pleated seat coverings and optional individual front seats were introduced. For the 1958 season, the seats were again improved with the pleated seat coverings being given padded rolls at the edges. These were covered in plain leather and gave better support for passengers. The woollen head lining that had been prone to staining, was replaced by a washable plastic one, available in two colours.

For 1959, interior changes reflected the new PS model. A padded roll was added to the wood-grain facial rail and new chromed handles were fitted to the glove box lids. A new style of clock was also introduced with a chrome bezel containing two adjusting knobs.

The 80 and 100 models were fitted with a key operated starter switch in place of the push button type and the later cars were given coat hooks and twin ash trays for the back of the bench front seat.

The introduction of the 95 and 110 models resulted in a new instrument panel which shared with the latest Mk II 3 litre models its clearer instrument faces and the large amber light that warned that the handbrake was on or that the brake fluid in the reservoir tank was low. Green direction indicator tell tales were set into the speedometer and the fuel, temperature and ammeter gauges now had a voltage stabiiser which prevented their readings from fluctuating. Spade shaped switches replaced the rotary type and a three-position main lighting switch now incorporated parking lights. The 110 was fitted with a new windscreen wiper switch that also operated the electric washers.

A new two-position switch replaced the petrol reserve solenoid valve and switch. This new switch operated the main and reserve petrol pumps that consisted of a double-ended fuel pump. This also had the advantage of providing a "back up" pump if the main fuel pump should fail while on a trip.

During production of the 95 and 110 models, reclining front seats were available as an option but the front bench seat was still fitted as standard. Crushable sun visors replaced the translucent plastic type during the 1963 season and a picnic table/utility locker was also offered as an optional extra, although this was extremely rare. Towards the end of production, Rover 2000 style courtesy light switches replaced the later P4 type during 1964 because their more positive screw fixings were more reliable than those fitted from 1959.

The Rover 95 and 110 models had been developed in order to extend the P4's life until the new P6 2000 would be ready. Rover wanted a years overlap of the P4 and P6 models to cover all eventualities and to maintain sales until it was clear that SolihnU's radical new creation would be a true success. It appears that Rover had learned that the public response does count when a new model is launched. They wanted a "bet each way" when the P6 was announced and this explains one reason for the 95 and 110 models being known as Mark I models. Should the new 2000 not be a

success, a revitalised 95 and 110, to be known as the Mark II version, could be quicldy brought into production to uphold Rover sales.

Sales of the 95 and 110 held up well during 1963 but once the new Rover 2000 appeared in October, sales of the P4 slipped badly. It now appeared that the P6 would be the success that Rover had hoped for and there would now be no need for the Mark II development of the 95 and 110.

The 95 and 110 remained in production through the early part of 1964 and for a little over six months the public had the choice of P4, PS or P6 models. Once the new 2000 found its market niche, there was no real point in continuing with P4 production.

The final P4 cars were built in the last week of May 1964, passing through the despatch department at the beginning of June.

The P4 was given a fitting send-off at a special "last of line" ceremony, the final P4 produced being a home-market 95. Unfortunately the Rover company records and photographic archives do not establish exactly which car was truly the last P4 or the date it was built. It is thought that the final build day was the 27th May and that the last car built had chassis number 760-03293, a burgundy 95. The cars did not always come down the assembly lines in chassis order; instead each car was allocated a line number which did run in sequence and this indicates why it is thought that the last car numerically was not the last car built. The last car numerically had chassis number 760-03297. This car was a charcoal 95 and appeared in the official company photograph of the "last of the line" ceremony. These final 95's received no special treatment and were sold off like all others and sadly no longer exist.

The final 110 built had chassis number 765-04340 and was a home-market car finished in pine green.
Over the northern summer of 1964, the old P4 assembly lines were ripped out and replaced by desperately needed assembly lines for Land Rovers. The very last P4 cars reached their new owners over the next few months, with a few remaining unsold until the beginning of 1965.