National Racing -- Clubman's Formula

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Twenty Five Years On

In response to WPK’s article on Clubman’s racing in the November 1990 issue in which some aspects of the cars in use came under criticism, Ray Mallock has written a robust justification of the formula, the cars and the technology employed.

1990 celebrates the 25th year of the Clubman Formula. Barring the 750 and 1300 Formula, with which it shares some affinity, it is the oldest national formula in the world. That it has survived this long and indeed is flourishing, can be attributed to the fact that it holds a specific and all but unique position in the motor racing world. WPK in his article in the November issue admits to not understanding what this is, so perhaps the time has come to remove the light from under the bushel.

In 1965, Tin Top racing was in its infancy, little more than a giggle to keep the spectators amused. Outside the International Appendix J classes, there were no proper formulae for sports cars, so if you did not own a Lotus 19 or the recently introduced 23, or the like, sports cars were restricted to the small club meetings with no proper classification. The 750 and 1172 Formulae catered for the ‘impecunious enthusiast’ but in 1965, the unreliability of the Ford side-valve engine had reached crisis point, whilst a maximum power of 66 bhp gave hardly electrifying performance. Rod Mansfield, (until recently chief engineer with Ford Advanced Vehicles and now with Aston Martin) organised a petition with 26 competitors’ signatures calling for a change to an unmodified Ford 1500 GT engine, but the 750 Club Board decreed that their Senior Formula was primarily for engine tuners. 26 competitors lost interest and the now 1200 Formula went into decline.

The Owner/Driver/Designer/Chassis Engineer to whom the engine was a necessary evil black box, had nowhere to practice his craft. The BRSCC recognised the gap and cunningly filled it with the Clubmans Formula.

Several expensive front-engined kit cars were already on the market, notably the Lotus 7 designed by Colin Chapman, the Terrier by Len Terry and the U2 by the author, soon to be followed by the Chevron (Derek Bennett), the Dino (Rod Mansfield), the Blaydon (Brian Lyles, recently moved from Tyrrell to CART), whilst Maurice Phillippe modified his Lotus 7 and Harvey Postlethwaite and Patrick Head did the same for their U2-based specials. There may not be many Sennas in the list as Engineer/Drivers have an aversion to bending their own designs but on the engineering front, the list reads much like a Formula 1 designers’ Who’s Who.

In 1965, the Class ‘A’ engine was a 1500 Ford push-rod, with a ‘soft’ bottom end. Anyone who could grind in a valve could get 120 bhp (comparable to F3 power of the period and quite enough to keep the chassis designer on his toes) just by bolting on a set of Powermax pistons, a pair of Webers and an A6 Cam. Reliability was 100% and there was no tyre war, as the Dunlop ‘L’ was the only suitable tyre on the market. Class ‘B’ was intended as a novices class with 1000cc, mostly BMC ‘A’ series engines.

Today, the position of the Clubmans Formula, now ‘Sports 1600’ and ‘Vauxhall Sport’ is even clearer. The meetings are full of ‘Spec’ Formulae and one-make series. Even where the chassis is not closely regulated, such as F3 where you buy a Ralt or a Reynard, or F3000 where the choice is Reynard or Lola, there is little scope for engineering. ‘Spec’ formula in all but name. Likewise Historic and Classic classes specifically ban any changes. The insistence on a front-engined layout means that the engineer cannot just copy current technology, but must develop his own ideas. Although variety is not what it was (seven makes in Vauxhall), no two cars are the same and almost to a man the drivers own, prepare and engineer their cars with help only from family, friends or semi-professionals.

Keith Duckworth is quoted as saying: “The success of any formula is closely related to the availability of a reliable, competitive engine.” I would add “at an affordable price.”

Clubmans has had its ups and downs in this respect. Sports 1600 has had a control engine and tyres for some years and now its success is almost too good for its health. Well-heeled teams, disenchanted with the tyre and engine wars in class ‘A’ tended to make ‘B Sport’ an end in itself, rather than a category for novices, learners and simply those who wanted to race for fun at low cost.

All this has now changed with the introduction of a control tyre and the wonderful 2-litre engine as used in the Vauxhall Lotus Challenge which costs no more than a new FF engine and lasts for ever! Class ‘A’ grids have risen from as few as 5 to 25 and more, whilst ‘B’ now serves its intended purpose.

In hillclimbs, the Senna/Prost parallel is much closer. The list of hillclimb champions is dominated by names like Douglas Osbourne, Cramer, Griffiths and Bolsover, all of whom served their apprenticeship in Clubmans, known as “The Formula 3 of hillclimbs.” But then in hillclimbs, every man is his own engineer.

The handling of Clubmans Formula chassis is well illustrated by the speedtrap numbers shown at the last Prescott meeting at the exit of the first blind left hander. None of the big single-seaters could break the 80 mph barrier with 500 + bhp, but Richard Thompson’s 1700 push rod with perhaps 185 bhp was fastest of the meeting by a substantial margin of 84 mph.

I am not too sure what WPK means by “lack of Space Age Technology.” Certainly many of the Sports 1600s are mid-’70 designs, but current cars are State-of-the-Art or ahead of it in several respects. Take ground effect. When this was invented, the sums said: “Use the largest possible, smoothest, tunnel area — the closer to the ground the greater the downforce.” Only the IMSA Ford Probe took the obvious choice and went front-engined, but Clubmans already had the engine in the right place! At first, Formula One decreed that it was impossible to run tunnels close to the ground, but today’s flat-bottom technology proves otherwise.

A current Mallock develops its sprung weight in downforce at 135 mph. This is well into the Cl/F1 area. Half of it comes from the underbody. Single wheel bump rate is another area where we lead the field. A stiff double wheel rate is needed for stable attitude ground effect, but for good ride single wheel rate should be soft.

This is difficult to arrange with conventional independent suspension, where single rate is often twice double. Fl designers are just beginning to tackle the problem. In Clubmans, it is already solved. What other technology is “Space age”? Push-rod linkages help to achieve a one to one motion ratio. We have had this, combined with upright wheels for 25 years!

Carbonfibre is correctly banned from chassis construction on cost grounds. The rules for chassis rigidity are simple enough. Mr Batho says concentrate the maximum amount of the most suitable material as far from the neutral axis as possible. This is exactly what our hybrid spaceframe/ monocoque chassis achieves. Aluminium honeycomb has no advantage in a front-engined layout and at 6000 pound feet per degree, our rigidity is in line with the best non-carbon layouts.

Aerodynamic research is one area where we must be slightly “off the pace” as wind tunnel time costs call for ingenuity to substitute for budget. Mike McDermott gets excellent answers from 50p’s worth of plastic tubing and coloured water. Jim Yardley tried a dozen such manometers until Silverstone Sid took exception. Our preferred alternative is Brunthorpe at £15 per hour.

Any aerodynamicist will confirm that wind tunnel results are notoriously unreliable, especially in a low clearance ground effect context. Every workshop holds a digital volt meter with a point one per cent resolution, so tiny changes in suspension travel can easily detect the smallest downforce change without ambiguity. Another ploy is to join forces with a friendly team to use the unexpended portion of an hour’s wind tunnel time. You can get a lot of runs in twelve minutes with practice.

Our Mk 22 was not a commercial success. It seems there is a limited market for front-engined Formula Fords, but it was successful on the track, as with all our FF designs. In 1968 our Mk 7 set more lap records and won more races than any other car except Tim Schenken’s Merlyn, and the Mk 9 won four of its last five races including the first UK FF race at a race average over 100 mph.

At one Castle Combe FF race, Mk 9s finished 1st, 2nd and 3rd. The Mk 22 was later converted to Clubmans spec and won the Class ‘B’ Championship at its first attempt. — RM