Chevron

Racing Cars from Lancashire

At any British race meeting these days one is tempted to ask where sports-car racing would be without the marque Chevron. Most of this year’s international and National British Group 4 meetings have featured a battle between Chevrolet-powered Lola T70 models, while an even more determined race has ensued in the 2-litre Class. Invariably it has been a Chevron-B.M.W. which has triumphed, in spite of the occasional intervention of a couple of Porsches, and the result has been a win for a private Chevron owner, John Lepp, in the 1969 R.A.C. Sports Car Championship.

While the Porsche opposition on the Continent has been far more effective, the Chevron GT has invariably acquitted itself well with a power deficiency of up to 40 b.h.p. The forerunner of the GT model was introduced as long ago as 1966, when the rear-engined concept proved far superior to the basically road-going Lotus Elans which were being raced in sports-car events at the time. The Chevron GT has been consistently successful with only minor changes since that time. What perhaps is even more remarkable is that in spite of a deluge of orders for the car, Chevron owners have nothing but praise for the factory staff, and in particular the founder of the Company, Lancastrian Derek Bennett.

Bennett, an instinctively clever designer with far less formal training than one would imagine, has also produced race-winning single seaters, and has recently announced a new Chevron GT car which bristles with ingenious technical features. At the beginning of September it won a decisive International victory in the hands of Redman at that most challenging of all circuits, the Nürburgring.

Bennett’s first contact with motor racing was not strictly “legitimate”, for he was attracted to the dirt-track Midget racing with which North West speedway owners were experimenting in 1956 and 1957. The somewhat rough and ready J.A.P.-powered design which he produced was successful enough to pay for itself, but that particular form of racing never proved very successful with its promoters, so Bennett turned his attentions to road-racing and the 1172 Formula in which so many other prominent racing-car designers, including Broadley and Chapman, served a form of apprenticeship. Unlike the latter two, Bennett continues to take part in races, and his comments from the cockpit have helped to ensure that every Chevron sold is instantly raceable.

The 1172 Special was a great success, even if it didn’t pay for itself, but a subsequent attempt at a front-engined Formula Junior car cost a lot of money. It was not until two years afterwards, in 1965, that another self-designed racing car was seen from the Bennett drawing board. However, Bennett’s driving ability was seen at the wheels of various GT and single-seat racing cars, including Lotus and Brabham designs. A Lotus Elite which held the Oulton Park class lap record for a while in Bennett’s hands had adjustable rear suspension designed by its driver, who was anticipating a feature common to every type of racing car these days.

1966—The Chevron GT

The first Chevron actually to carry the name was an open two-seater with cycle-type wings. Designed to compete with a newly announced development of the Lotus 7 in Clubman’s Formula racing, it was of the regulation front-engined configuration. The space-frame chassis incorporated independent rear suspension, like the new Lotus (of which only one example was ultimately built), and many people considered that this gave the car an unfair advantage. Other, wiser, souls put down their names for replicas, and there are still half a dozen Clubman’s Chevrons winning races for this newly-revived form of car.

Bennett was running a general motor repair business as well as undertaking the construction of cars and tuning racing engines, and his Salford premises became somewhat cramped under the influx of work, so he moved during that year into the Bolton cotton mill where the Chevron factory remains today. Needless to say, another move is proposed, once planning permission has been obtained, for the existing site simply cannot cope with the construction of cars, crash repairs and engine building, all of which are executed at the Chevron factory itself.

In addition to winning the first-ever race to fall to a Chevron, at Kirkistown in 1965, Bennett was taking part in Libre races with a Brabham sponsored by the VIP petrol company, which has its headquarters in nearby Eccles, and he had been tempted to build his own single-seater as the next project. The field was of course well covered by Brabham, Lotus, Lola and others, so instead he turned his attentions to a rear-engined GT car. Not only was its chassis immensely robust, but the elegant bodywork was also a Bennett design and the car created something of a sensation in the paddock at Oulton Park when Digby Martland arrived—unheralded—with it at a club meeting in July 1966. Martland’s faith in the new design was more than justified and he went on to collect race victories, lap records and admiring glances all over the country. The this first Chevron GT was fitted with a 1,600-c.c. Lotus-Ford twin-cam engine and a Hewland Mk. 5 gearbox, but the second car used a 2-litre B.M.W. power unit, with which the model was eventually homologated in 1968, Chevron having convinced the F.I.A. that 50 cars had been built, while the Formula Two-type Hewland FT200 gearbox also supplanted the Mk. 5 variety.

A feature of the GT car was a form of chassis reinforcement by means of spot-welding steel sheet on the outer and inner extremities of the chassis frame in the area of the driver’s compartment. The resulting box-like structure has caused some observers to dub the Chevron a monocoque design, although this is not strictly correct. Nevertheless, this method is immensely strong, as many drivers have unwittingly proved in numerous racing accidents.

Various improvement and modifications have culminated in the latest version of the GT car, which is known as the B8. As racing cars go, it is remarkably easy to drive. It is not just a club-racing special, either, for it has taken part in every major long-distance race on the Calendar, including the Targa Florio, Mugello, and even the American contributions to the World Championship of Makes. Suspension layout is entirely “classic”, with wishbones at the front, upper and lower links and trailing arms at the rear, utilising proprietary front uprights and a cast alloy Chevron pattern at the rear. Brakes are outboard all round and the only alternations which Bennett has seen fit to incorporate over the three years since 1966 are calculated to take advantage of wider wheels and tyres or to comply with F.I.A. safety regulations.

More than one privateer has seen the Chevron chassis as an ideal basis for a special one-off sports car. Among the first were two of the patrons of the sport. John Bridges has had considerable success in British racing with a Chevron GT powered by the Cosworth FVA Formula Two engine and last year he became a Director of the Company. A semi-works team of Formula Three Chevrons was run by John in 1968 under the name of his garage, Red Rose Motors in Chester. David Bridges, who has raced various Brabham, Merlyn and Lotus cars in the past, commissioned yet another special Chevron, this with a 2-litre Tasman B.R.M. V8 engine, in 1967, and although it was very promising in theory, in practice the transmission was never very reliable until the car was completely rebuilt by another privateer early this season, since when it has shown considerable speed. In 1968, an even more exciting Chevron GT was ordered by the late John Woolfe, this being fitted with no less an engine than an ex-Brabham 3-litre V8, the object being to win the Group 6 class at Le Mans. Although Woolfe had several club-racing successes with the car, it was never fully sorted-out and its demise with engine trouble in the 24-hour race at an early stage was not entirely unforeseen.

The regular B.M.W. engines supplied in the Chevron are entirely assembled at the Chevron factory from standard and special German parts. There is quite a degree of co-operation between the B.M.W. factory and Chevron, some of the parts (as well as certain advice) emanating from Munich. For the 1969 season an additional 10 b.h.p. was persuaded out of the Weber-carburated 2-litre engine to bring the output up to between 190 and 195 b.h.p. There have been some oil-pumping problems with this year’s engines, although the factory reckons to have solved them. It is a remarkable testimony to the strength of the basic B.M.W. design that the racing engine continues to use a standard crankshaft and connecting rods, but this year some owners have replaced the rods with an expensive American design in the search for additional revs. During the current season, the B.M.W. factory loaned a special 210-b.h.p. works unit to Chevron for use in the works GT car, but it has not proved a great success, being difficult of the driver to control thanks to an unprogressive design of throttle linkage.

Nevertheless, the use of the B.M.W. engine has kept the price of the car within low bounds by Porsche standards, the B8 having been priced at a very reasonable £3,150, ready to race.

For Formulae Two and Three Chevrons

Bennett’s urge to get into the field of building single-seaters materialised late in 1967 when he produced a very neat and tidy Formula Three car, driven at its Brands Hatch debut by Gethin. It was put into production, with minor improvements, for the 1968 season and two cars were raced on behalf of the works, by the Red Rose team, as related above. Irritating engine failures, several accidents and other set-backs prevented the cars from attaining the victories which they probably deserved, while the two drivers involved, both of whom were highly experienced and previously successful in the Formula, found it very difficult to get on terms with the cars. Bennett was quick to make alternations in the design, and for the September Bank Holiday meeting at Brands Hatch he had produced a somewhat different model incorporating the plated reinforcement which had proved its worth on the GT car. The car took an impressive victory and there was further consolation for Chevron when a second major Formula Three race was won by Schenken in October. Perhaps because Schenken suffered none of the vicissitudes which struck the works cars, he had more success. Several impressive wins—including an unbeaten record at Oulton Park—won for him the Lombank Trophy as the most successful Formula Three driver in club racing.

The “plated” chassis was not substantially altered for production in 1969; indeed, most of the suspension settings were exactly the same as in 1968, but the car has been far more successful, for a reason which even the factory staff cannot explain. This year the works have run a singleton car for the Swedish driver Reine Wisell while Bridges concentrates the Red Rose efforts on sports cars. Wisell has been one of the most successful Formula Three drivers and the Chevron has proved to be the most impressive British-produced Formula Three car, although that claim will probably be challenged by Brabham!

A Formula Two car was also produced by Chevron in 1968, and this suffered an even worse fate than the Formula Three, for Gethin, who drove it on behalf of Frank Lythgoe asked to be relieved of the responsibility of racing it following some disappointing outings. Lythgoe, who was running the car as a privateer with works support, concurred, and Gethin was seen in a new Brabham for the remainder of the season.

Small and compact, the Formula Two Chevron looked very promising. Bennet regrets now that he tried to do so much in the space of one season, for—given the time—he was sure that the Chevron could have been made into a Formula Two winner. He did not discover until after Lythgoe had been racing the car for some time that Brabham wheels were being used on the car in the interests of increasing rim width, regardless of the fact that the amount of off-set was entirely different. It seems likely that Redman, who was racing an F.2 Lola for David Bridges, and was impressed by the Chevron, would have taken on the task of development if he had not suffered an accident which kept him out of racing until the end of the year.

A New Sports Car—the B16

The latest Chevron is a replacement for the faithful B8. Shapely and low (no higher, in fact, than the roll-bar of the Formula Three car) it carries on the constructional methods of the previous design with several ingenious deviations.

The chassis takes the form of a shallow multi-tube frame (almost in the “birdcage” tradition pioneered by Maserati), forming a separate chassis centre-section, the sills of which are panelled in aircraft specification LM72 aluminium, riveted and bonded to the sides of the chassis to form the outer skin. The remainder of the centre-section is skinned with sheet steel, the thickness of which varies from 22 to 26 gauge.

The centre section, however, is not a complete chassis, as it was on the previous series of GT cars, for there remain two tubular subsections which are bolted to the skinned portion. The reason is that accidents invariably damage either the front or rear of the car, which then—in the case of one-piece chassis—must be returned to the factory for a complete strip-down and repair. Not only does this cost the customer money, but it clutters up the factory floor with repair work invariably at a time when the factory staff are trying to get new cars built for their anxiously-awaiting customers.

Even a bent rear body mounting can put a driver out of the race, so the principle of this later method of construction is that the customer should carry spare front and rear sub-sections against the possibility of an accident, which must be very severe indeed to affect the expensive “meat” of the centre section. The rear sub-frame carries body mounting point, so there is quite a considerable strain being carried through the bolt-on lugs.

The idea is not entirely new, having been pioneered by McLaren’s Can-Am cars, but it is just an example of the several ingenious features with which the car is sprinkled. Another, for example, is the mounting of the oil tank in the near-side front of the body, where it conveniently balances out the weight of the driver. The doors incorporate intake ducts for cooling not only the oil and rear brakes, but also the driver. Once sufficient speed has been attained, the air pressure inside the cockpit causes small quarter-vents to pop open, permitting the passage of cool fresh air through the cockpit itself. A cool driver invariably drives more quickly than a hot sweaty one.

Although the prototype B16 has been doing its early running with a B.M.W. engine, the production version will use a long-stroke development of the Cosworth FVA engine, re-designed FVC. Its capacity will be 1,840 c.c. and the power is estimated at 240/250 b.h.p., with a significant increase in torque by comparison with the comparatively peaky F.2 engine. A decision about gearboxes has yet to be made, although a development of the Hewland FT200, using a stronger c.w.p., is being considered, with its own separate oil coolers.

The esteem in which drivers hold Chevron racing cars is revealed by the fact that 16 firm orders, including the necessary deposits, had been received within less than a month of the new car’s first public appearance. The first order came from a faithful customer who had no idea at all of the car’s shape, its engine, or—more importantly—its price!

Production

As with most other racing-car builders, chassis are not built by Chevron, apart from the prototypes. The work is farmed out to one of the two important tube-bending factories which undertake this type of work on behalf of the car manufacturers. Next year’s B16 model will be built by Arch Motors in Huntingdon, while the single-seaters will come from Racing Frames of Hertfordshire, the latter firm already being responsible for making suspension wishbones, etc.

Castings come from Sterling Metals, while the flawless fibre-glass bodywork is the product of Specialised Mouldings, but as much of the works as possible is one by the Chevron people themselves, all the mounting bushes are Chevron-manufactured and all machining is undertaken in the Chevron machine-shop, and acquisition from the “firm next door”.

The chassis arrive unpainted and unpanelled from their makers and this last important part of the job is completed by Chevron’s four skilled sheet metal workers before the chassis are sand-blasted and painted. At present there are four car assemblers, but the number will be increased to six one the new factory is open, which is expected to be in early 1970. There are presently two engine-builders and production is supervised by Dave Wilson, formerly Chief Mechanic to the Red Rose F.3 team.

As Managing Director, Derek Bennett has one full-time and one part-time draughtsman to assist him. Paul Owens, who has been with Bennet over since the Midget days is Racing Manager, while Doug Linton is the Company Secretary and deals with sales inquiries. With a Buyer and a Secretary, that’s not a very high task-force, yet 1969 has seen the production of 21 B8s, 14 B15s (the F.3) and eight B15Bs (the F.B.).

It seems certain that Chevron will be busy for many years yet.
M. G. D.