Part 5: The Legend of Lotus 25 R 4
I came across the 25R4 – the car shown in Part 4 after introducing the vast topic through Part 1, Part 2 and Part 3 of The Long Read – which for Lotus fans is the 8th wonder of the world, whilst sheltering from the rain in the pit garages at Spa Francorchamps. I’d love to find one in a barn, but this was an impressive second best!
Not only did I see the car, but I also met the owner, John Bowers, Bob Dance (one of the original Team Lotus mechanics although not on this car) and Andy Middlehurst, the racer entrusted to race the car. To my delight, all three agreed with bubbling enthusiasm to talk me through it.
In Jim Clark’s hands, this chassis, 25 R 4, won the 1963 Belgian GP at Spa Francorchamps as well as the Dutch, the French and the British GPs. This was Jim Clark’s first championship winning car (he just missed the 1962 World Championship through an engine seizing 10 laps from the end of the South African GP).
In the late 60s, the car was not really valued or treated with much deference: it carried on racing with Reg Parnell Racing and was then modified for antipodean events. Indeed, it was jokingly later described as also being chassis “R13” as the rear gained Lotus 33 modifications.
The 25 and 33 are very similar. The main difference to the monocoque are the straightened fuel tank boxes / monocoque tubs (the wheelbase of the 33 is longer) and it is apparently stiffer.
Chassis 25R4 was rescued by John Dawson-Damer after being laid up in 1970. Sadly, Dawson-Damer was killed in a crash at Goodwood in 2000 and the car disappeared into estate discussions.
Racing again
In 2009, the car was auctioned in Australia and purchased in 2009 by another Australian, John Bowers who brought it to Europe and entrusted it to Classic Team Lotus to put it back onto the track after a very long break.
This car is no garden party exhibit. Since 2009, 25R4 has competed in 43 races at many of the circuits of its “youth”: Brands Hatch, Goodwood, Oulton Park, Silverstone, Spa Francorchamps, Zandvoort, Monaco, Clermont Ferrand-Charade, and Monza.
If we exclude the single outing in 2009, that means that the car has done nearly five races per season on average which shows the determined passion of the owner to present and not least use this truly remarkable race car.
Briefing
Bob kindly explained the car to me which has been rebuilt several times. It is a precision model of packaging that weighs 475kg (it was a fraction lighter in period). The expression “tub” is apparent as is the low-slung nature of the car. The photos taken in the pit garages at Spa (see Part 4) help us to gauge exactly how the Lotus 25 is quite so radical.
The black “bomb” in front of the radiator is the fuel pump! The compact radiator has combined water and oil elements and has the pointy shaped oil tank (dry sump) for the 190 bhp Coventry Climax FWMV V8 just behind it. Included in the very tight packaging it is possible to note the cooling ducts for the front dampers next to the brake balance bars. The fuel tanks are of course invisible bladders inside the pontoons, but the siamesed fuel tank fillers look fragile and filling the tanks is a delicate procedure.
I did not spend hours contemplating the engine (but I now know that there is a crossplane and a flatplane version) or the transmission (a 5-speed ZF and a Colotti were used in period), but I did notice the “trouser legs” (the engine cradle) and the complicated exhaust system.
Set up
Whilst I was talking with Bob Dance, Andy Middlehurst – one of Classic Team Lotus’ racers – confirmed some of the technical set up points which I wanted to understand from the Lotus 25.
Firstly, as the car is so light, what are the spring rates on such a car? Andy informed me that current rates are apparently 300 lb/inch at the front and 200 lb/inch at the rear. This is close to twice the rates used in period!
Possible explanations: this seems to be related to the change in tyres (modern historic tyres), much smoother track surfaces and 58 years of research (since the pioneering period of the Lotus 25) as to what goes fastest. At the time Mike Costin wrote: “the basic requirements are a stiff chassis, advanced independents suspension and soft springs”.
Secondly, have the dampers been changed? The dampers are newer and more efficient, but they remain “one way” as required by historic rules. This little detail seems to be frequently overlooked in the pre-66 GT paddock…
Thirdly, how much adjustment is done through the anti-roll bar (only on the rear axle)? None: the whole bar is changed… according to track conditions!
I was curious to also ask whether the car had any other major geometrical tricks to the Ackerman angle but apparently not. Andy’s advice was that the car must be driven “smoothly to carry speed” and avoid movements as there is a “lack of grip”. This lack of grip refers to the thin Dunlop Racing tyres (on 13” wobbly web wheels) that historic racers use in most circumstances except for endurance / road use.
Dunlop Racing tyres do not offer much grip especially in the wet where they are also closely associated with the notion of aquaplaning…
“How fast, Mister?”
25R4 and 25R5 (the only other 25 which is still racing) are rare and precious and as such, they are not the ideal car for horticultural excursions. The 25R4 race car is highly original in its configuration: it is not a “modern historic”. 25R4 has a very original 1.5-litre V8 engine and produces around 190 bhp (127 bhp per litre) at 10,000rpm.
The following comparison is therefore iconoclastic and must be understood in its context! I am always curious to understand how cars relate to each other on a track and to get a better idea I have picked two other Lotuses to get a greater understanding.
Firstly, the Lotus 20/22 that won the pre-1966 Grand Prix race at the 6H race meeting at Spa last year. This car, driven by Horsman, seemed faster than I was expecting. Which made more sense once I discovered that it is currently fitted with a 2.5-litre “Tasman” engine. I would expect this to have nearly 240 bhp.
Secondly, one of the front running Elans, the Shapecraft 26R raced by Michael Schryver. Bear in mind that a modern FIA legal 4-cylinder 1594 cc Lotus Elan engine will produce approximately 185 bhp at 8,000 rpm (116 bhp per litre) compared to perhaps 160 bhp in period.
Michael Schryver’s red shapecraft Elan. (Courtesy of Michel Schwauers)
I am not familiar with the weight of the 20/22 but I would expect it to be close to the 450 kg of the Lotus 25. In comparison, the Elan’s homologated weight is a massive 580 kg (Form 127), but this weighty corpulence is explainable by the comforts and options needed for road homologation.
I then had a closer look at best sector splits (not always on the same lap and during the dry Friday qualifications) and we get a better picture of the evolution…
| Car | Sector 1 (La Source, through Eau Rouge, Raidillon, Kemmel) |
Sector 2 (from Combes to Stavelot) |
Sector 3 (from Paul Frère to La Source |
Speed on Kemmel straight radar trap (not top speed) |
Fastest lap (not the assembly of the best sectors) |
| 25R4 (Middlehurst)
1.5 litre V8 |
45.58 | 1:16.82 | 42.63 | 216 kmh | 2:47.73 |
| Tasman 20/22 with 2.5 litre 4-cyl engine (Horsman) | 45.57 | 1:18.02 | 42.78 | 216.9 kmh | 2:46.65 |
| 26R 1.6 litre 4-cyl
(Schryver) |
49.86 | 1:19.96 | 45.69 | 213.9 kmh | 2:55.84 |
The theoretical fastest lap for the 25 would have been closer to 2:45, but I’m sure that we are not comparing “apples with apples” as the Elan and the Tasman 18/21 have been carefully developed and the latter has a 1-litre advantage of extra capacity.
Enthusiasm
E – words are at the heart of most Lotus road cars (from Eleven, Elite, Elan, Europa, Esprit, Eclat, Excel, Elise, Evora, Evija) and Lotus ownership.
The Enthusiasm for dynamic firms is highly infectious. Young enthusiasts gave up their spare time to get Lotus onto successively higher rungs of the competition ladder. Enthusiasm is highly infectious… Colin Chapman’s gift was the management of this escapism.
It is fascinating that the Lotus Purchasing Manager came up with the concept of the race car “tub”, that bright engineers like the Costin brothers gave up much of their spare time, that the race mechanics worked all hours and that big companies (Coventry Climax, Ford and ZF) were caught up in this adventure.
Mostly, the “e-word”: errors, were avoided. But whilst Lotus cultivated throwing about ideas to improve chassis, suspension and transmissions, Ferrari was focussed on engines. Both firms made management errors. Chapman let slip key men to cite just Keith Duckworth and Mike Costin (founders of Cosworth) and Ferrari saw the departure of its star F1 and GT engineers in 1961-62 to found Automobili Turismo et Sport. Carlo Chiti and Giotto Bizzarrini – both were just a fraction older than Colin Chapman.
I would like to acknowledge, the enthusiasm of John Bowers in making sure that 25R4 is used as its enthusiastic engineers and mechanics always intended.
