Lightweight SPL

He worked alongside Chapman at Lotus, so it’s no surprise that his choice is so named. This home-built racer is innovative, compact and effective. And its designer also penned the mini.

Since venturing into the speed Hillclimb scene this year, I have become increasingly conscious of the pioneers of the sport — especially those of the between-war years who spawned a welter of innovative and eccentric vehicles. Of these, Alec Issigonis “Lightweighe” was a high point of ingenuity and vision which still impresses me.

It was a frugal age and, as yet, there was no supply base of parts, engines and expertise. There were few cars in any category that were made in any numbers. It was down to the inventiveness of the British engineer to explore the unknown, to create their own cars and tune their own engines by hard graft and experiment This was especially evident in the up-to-1500cc single-seater classes.

Many constructors chose to modify the various JAP twin-cylinder engines, other motorcycle units or the ubiquitous A7 power plant. They mounted them on modified GN chassis or their own steel ladder-frame, sprung the wheels/beam axles on quarterelliptics and perched themselves on top, with little or no body work (aerodynamics were not often considered essential). This may not appear to be a pinnacle of design when viewed from the 21st century, but the atmosphere in the paddock, with the multitude and variety of home-made machines, must have been inspiring, unlike today’s limited entry lists.

Some of those cars stand out for me as beacons of expression. Firstly, John Bolster’s 1929 ‘Bloody Mary’, a car that started off with an aged 760cc JAP slung alongside the driver in a three-rail wooden frame. This amazing 31bhp assemblage of modified mad car and home-made parts tipped the scales at just 230kg. Total cost: £70! Adding a second engine in 1933 enabled him to break numerous records until the war stopped activities and led to disuse and decay. However, after hostilities, the car was dusted down and continued to break records for several years.

Then there was David Fry and Dick Caesar’s Freikaiservvagen, also a curious name given the date, but perhaps influenced by the Auto Unions that inspired them. Its suspension was by rubber bands and coil springs, and the tubular frame was airpressurised to assist fuel feed. By 1948, the supercharged rear-mounted 1100cc twin pumped out about 125bhp in a vehicle weighing just 260kg, helped by discarding the bodywork which caused overheating. With 4-inch-wide front tyres and 5inch rears, and front brakes only, this car, driven by Joe Fry, eventually ascended Shelsley Walsh in a record-breaking 37.35sec, a time that would not disgrace many a modem competitor.

But all contenders, in my eyes at least, paled alongside the ‘Lightweight’. This was a professional concept, which stands out from its spartan, starkly functional rivals. Issigonis began this project in 1933, after several seasons of racing and modifying a super charged Austin 7. The radical design took six years to implement at his home during his spare time — he was Chief Engineer at Morris Motors. The story goes that the original drawing was pencilled on the wall in his garage, and that when he moved, he had to start again!

The workshop where construction was done had no power so everything had to be cut, drilled and formed by hand. All the parts were laboriously worked on and lightened until funds permitted more bits to be bought.

The radical exposed chassis was on composite plank principles, much like many modem junior formulae, using ply and 28swg aluminium skins,efficiently cross-braced (mainly using the engine, seat and differential).

Suspension was by rubber bands on front wishbone and rear swing-axle principles, and then enclosed in aluminium fairings. The ‘works’ side-valve Austin 750cc engine, Zoller supercharged to such a high boost that many extra head and block studs were needed to hold it together, was hung down very low so that the propshaft ran under a conventional-height seat, and was then stepped up again to the differential.

Special ‘Electron’ cast wheels with integral brake liners and hubs were further lightened with ever more holes, and the whole car was beautifully finished off with attractively-shaped and louvred aluminium panels. The end result was likened to a miniature GP Mercedes-Benz.

Even the seat was properly upholstered, but of course in lightweight cloth, not leather. And the steering wheel was near horizontal, a portent of the Mini driving position. Nothing was compromised, which enabled the lightest and most soundly engineered ‘special’ in the category to be produced.

Slightly larger than the two specials mentioned here, and despite an engine of 115kg, the all-up weight was just 270kg. To put that into perspective, if a modem bike engine was used as a replacement, this would equate to about 230kg, very nearly as light as my own carbon mono coque hillclimb cat the PCD Saxon. This was a highly adventurous vehicle, designed and manufactured to a high standard, and with a purity of vision that inspired myself and many others treading the same path.

It proved to be very rapid, winning sprints and hillclimbs with both Alec and John Dowson at the wheel. Interruptions because of the hostilities, and transmission failures due to the development Nuffield engine’s extra power, did little to slow it down, and with this revised engine spec it raced with success for several years. It is still participating, in near original form, a tribute to the design and workmanship of some 30 years earlier.

It is said that there is nothing new in racing, but the pre-war engineers did their bit to bring exciting features into design, whereas the plethora of regulations and lack of interest by manufacturers and legislators fails to promote such attitudes today.