Duncan Russell looks at the development of four wheel drive and Ferguson Research. (Duncan’s article from From Journal 64, Spring 2010 has been kindly updated by Bill Munro (author of “Traction For Sale”) in October 2023, the update is below……..

Prior to the article here is an interesting video of the Ferguson flat-4 engine; It’s the only fully-operational Ferguson flat-4 engine, demonstrated at the launch of Traction for Sale at the British Motor Museum, Coventry on 12th May 2019.

The engine has a single overhead cam par bank, driven by a toothed belt. This is believed to be the first known application of a belt drive to a camshaft, though not in a production engine

Bill Munro looks at the work of Harry Ferguson Research in the field of full-time Four-wheel drive.

During the 1930s, racing driver Fred Dixon was saddened by the growing number of deaths caused by road accidents and he hatched an idea to design a super-safe family car with four-wheel drive and four-wheel steering. When he raced at the Ulster TT, his car was garaged by Harry Ferguson and the two men would discuss Dixon’s ideas at length.

Dixon’s fellow racing driver, Tony Rolt acquired an ERA racing car in 1937 and he engaged Dixon as his racing mechanic. Intrigued by Dixon’s ideas, Rolt put up some money to form a company, Dixon-Rolt Developments Ltd to pursue the work and in a workshop behind Dixon’s house in Reigate, Surrey they built a prototype, which they called the Crab. It had four-wheel drive and four-wheel steering, but it could not be steered and braked at the same time. Clearly, much more work needed to be done. Rolt was a serving army officer and when war broke out in 1939, he was sent into action in France, was captured in the retreat to Dunkirk and ended the war in the infamous Colditz Castle. When he returned to England, he met up with Dixon and the two restarted work on the Crab.

The ‘Crab’, Dixon and Rolt’s first attempt at a 4WD Vehicle.

Rolt knew that Dixon-Rolt Developments needed capital. Harry Ferguson had won £9m in a landmark patent infringement case against the Ford Motor Company and in 1952, Rolt approached him to see if he would be willing to invest in their company. Instead, Ferguson bought the company and renamed it Harry Ferguson Research Ltd. New premises were found in nearby Redhill and design engineer Claude Hill was recruited from Aston Martin. A second prototype was developed, numbered R2, with a vertically mounted 4-cylinder Scotch Yoke engine at the rear. After testing it at Abbottswood, a pressed steel body was built for it. However, Dixon’s original four-wheel drive system didn’t control wheelspin, as it needed to do. Thinking hard on the problem, Harry Ferguson said, “what’s wanted is a diff that diffs when it should diff, and doesn’t diff when it shouldn’t.” He gave Claude Hill the task of making that a practical reality. Hill devised a mechanically controlled centre differential that locked when wheelspin was detected and immediately unlocked when traction was regained. That was the heart of what was, at first called the Ferguson Principle.

Meanwhile, Ferguson moved the company to his tractor factory in Coventry, which Dixon disagreed with and he left the company. At Coventry, a new four-wheel drive prototype, R3 was developed, fitted with a fibreglass estate car body and a flat-4 engine of the company’s own design. The plan was to offer the complete package to a major motor manufacturer to build under licence, in the same way that the tractors had been built, but no manufacturer was willing to take up the offer.

In 1954, Ferguson, having parted company with Massey-Harris was obliged to move Harry Ferguson Research out of the Coventry works. A temporary home was found at Chipping Warden airfield, where a further research car, R3F was built, using a platform chassis and the R2’s body crudely modified to accept the totally different mechanical components. This was registered as RPE 4, though later, erroneously referred to as R4. It is now on display at the Coventry Transport Museum.

Ferguson R3F, an interim research car using the body built for R2 and using a Ferguson flat-four engine, mounted on a platform chassis.

A total of three prototype road cars were built, two estate cars and a saloon.

Ferguson Research Car R3F as it is today, on display at the Coventry Transport Museum

Ferguson built new premises at Siskin Drive, Coventry in 1956 and there, in 1959 work began on a fourth generation Research Vehicle, R4, with a similar platform chassis to that of R3F and an estate car body designed by Giovanni Michelotti. A year later, work began on what is perhaps the most famous Ferguson four-wheel drive car of all, the Ferguson-Climax Grand Prix car, P99.

Ferguson R5 Estate car prototype; One of two Ferguson R5 Estate cars built. Both survive, in the possession of the Coventry Transport Museum

The Ferguson P99 with Stirling Moss at the wheel, testing at British Grand Prix 1961.

P99 conformed to the new Formula I regulations for 1.5 litre cars, but all this generation were rear-engined and P99’s handling advantage was much less than it was with the older front-engine cars. P99’s racing programme was run by Rob Walker Racing and its first race was the British Empire Trophy Race at Silverstone, with Stirling Moss as the driver and Jack Fairman as reserve. However, brake failure forced retirement. It was entered for the 1961 British Grand Prix at Aintree. After practice, Moss, prioritising his championship chances, considered that the car was not developed sufficiently to be a serious contender and started the race in a Lotus. Jack Fairman started the race in very wet conditions, but after the car developed a misfire, which was fixed, Moss took over and brought the car up to second place. However, he was black-flagged because the car had been push-started. Moss drove P99 in the Oulton Park Gold Cup race in 1961 where the damp conditions suited the four-wheel drive and Stirling won by some considerable margin. It was the first and only Grand Prix win by a 4WD car.

Sadly, Harry Ferguson did not see P99 compete. He died in 1960 and the chairmanship of the company passed to his son-in-law, Tony Sheldon. A further research model, R5 was developed, as an estate car with a 2-litre overhead cam version of the flat-4 engine. Two examples were built, the grey R5/1, which later was fitted with a Paxton supercharger, and the blue R5/2. Both survive in the Coventry Transport Museum warehouse.

Tony Sheldon scrapped Harry Ferguson’s original plan, to offer a complete vehicle package and instead the company began developing a range of systems that could be offered to car makers for fitting to their existing cars. At the time, only one maker, Jensen took up the offer, introducing the 4WD Jensen FF (for Ferguson Formula). This was also the first production car to incorporate the Dunlop Maxaret anti-skid braking system, which was now an integral part of the Ferguson Formula.

In 1969, GKN bought into Harry Ferguson Research and acquired the rights to mass-produce the four-wheel drive systems, which promised to bring down the cost of the four-wheel drive systems dramatically. However, when a plan to build a four-wheel drive version of the new Ford Capri using GKN-built components fell through, Tony Sheldon pulled the plug on the research work and in 1971 the company was closed.

Just before the closure, a new type of control system for the centre differential, the Viscous Control, or VC was invented, which was far cheaper to build than the old mechanical unit and totally reliable. Tony Rolt believed this was the route to success and with Sheldon’s blessing formed his own research company, FF Developments Ltd. In the late 1970s, after several attempts to sell the system to the motor industry, American Motors took up the Ferguson Formula, with the VC, for its new all-wheel drive Eagle. This was the first mass-produced car with full-time four-wheel drive, beating the Audi quattro to market by a matter of weeks. Ford then took up the system for the Sierra and Scorpio 4×4 and Ferguson’s four-wheel drive system, in various guises was adopted by many makes around the world, including Volvo, Audi, Subaru, Lamborghini and Volkswagen. In 1994, FF Developments was bought By Ricardo Plc and is now Ricardo’s Driveline and Transmission facility.

P99 is now in the custody of the Rolt family. It was raced in historic events until 2017 but is now only driven in demonstration events.

Originally published in Journal 64, Spring 2010, Duncan Russell – updated by Bill Munro – October 2023