Featherweight Flyer - a Historical & Technical Appraisal of the Lotus 6
BACKGROUND
Having studied structural engineering at University College London, Colin Chapman left higher education without a degree in 1948. He subsequently went on to do a brief stint with the Royal Air Force before taking up a technical sales role with the British Aluminium Company.
1948 also saw Chapman create the first Lotus-badged car, the Mk1, a trials special based on a 1930 Austin Seven which had remained unsold following a short-lived foray into used car dealing. Thanks to a number of innovative features, the Mk1 proved immensely competitive in the 750 Motor Club’s burgeoning 750 Formula that promoted sporting use of the ubiquitous Austin 7.
With a mix of prize money and his salary from British Aluminium, Chapman was able to conceive the more competition-focused Mk2 in 1950 which not only established itself as an effective mount for trials, but circuit racing and sprints as well. By this time, Chapman had obtained his degree having sat a final mathematics exam in 1949.
During 1951, Colin Chapman’s third Austin Seven-based Lotus emerged, the Mk3, which was even quicker. Ongoing success resulted in several customers commissioning Chapman to work on their own cars and meant the fledgling Lotus operation had to move from a small garage owned by business partners Nigel and Michael Allen to the old stables behind Chapman’s father’s pub (The Railway Hotel on Tottenham Lane in Hornsey, north London).
A Mk3B built for a customer along with a Mk4 then followed, but a proposed 100mph Austin Seven-based machine dubbed the Mk5 never got beyond the drawing board.
Thanks to a combination of accumulated winnings, work for customers and sales of his already built machines, over the winter of 1951-1952 Chapman was able to create the first true Lotus based around a chassis of his own design: the 6.
Conceived for the 750 Motor Club’s new 1172 Formula which, unlike the 750 Formula permitted the use of a specially fabricated chassis, development of the Lotus 6 continued through the first half of 1952 with the aim of creating a platform suitable for circuit racing, sprints, hillclimbs and even trials.
To avoid the 60% Purchase Tax on new cars sold in the UK, the Lotus 6 would be supplied to customers as a kit of parts in varying states of completeness. To finish a car, items like the engine, gearbox, axles, wheels, lighting and instrumentation had to be sourced separately. In terms of the major mechanical components, most buyers opted for relatively inexpensive and readily available components from Ford and MG.
The Lotus 6 prototype (chassis L176/1) made its debut at the MG Car Club’s Silverstone race meeting in early July of 1952 where Chapman and Michael Allen collected a brace of second place finishes. Following this impressive showing, the first customer replica was ordered.
The Lotus Engineering Co. Ltd. was subsequently established in September 1952 to specialise in automobile and component manufacture along with racing and competition car design and development.
The first Lotus 6s bound for customers were then assembled over the winter of 1952-1953.
CHASSIS
Colin Chapman designed a quite complex semi-monocoque chassis for the 6 that comprised a tubular steel spaceframe with stressed aluminium panels riveted to the side panels and underside. Unadorned, the tubular chassis weighed in at just 25kg which rose to 41kg in fully clad semi-monocoque trim. The fuel tank was mounted low behind the axle.
With the exception of the prototype (built in-house by Nigel Allen) each chassis was constructed for Lotus by the Progress Chassis Company (also based on Tottenham Lane and run by Chapman’s childhood friend, John Teychenne).
Customers could run whatever suspension set-up they desired (or could afford).
The independent front suspension conversion offered direct from Lotus comprised a Ford Ten swing axle which was split in half and adapted to run coil sprung damper units instead of the original leaf springs.
Lotus’s preferred five-link live rear axle with radius arms and a Panhard rod was similarly imported from the Ford Ten, albeit modified with a shortened torque tube to suit the 6’s more compact 2210mm wheelbase. As per the front, coil sprung damper units were installed.
Steering was via a modified worm and nut box from the Ford Ten that minimised the number of balljoints between the steering and road wheels.
Brakes were typically cable-operated 254mm diameter Girling drums of the type fitted to most Fords of the period.
The 4 x 17-inch pressed steel disc-type wheels normally used were imported from the Ford Popular.
ENGINE / TRANSMISSION
Lotus designed the 6 so that customers could assemble their car with one of several different front longitudinally-mounted inline four cylinder engines.
Most frequently selected were a brace of Ford motors.
Smallest of these was the all-iron Ford Sidevalve / Flathead unit found in models like the Anglia, Prefect and Popular which in standard trim displaced 1172cc thanks to a bore and stroke of 63.5mm and 92.5mm respectively.
If equipped with an increased 8.5:1 compression ratio and a pair of SU sidedraught carburettors, peak output went from 31bhp at 4000rpm to between 40bhp and 50bhp at 5000rpm to 6000rpm (depending on the rest of the upgrades fitted). The torque rating was typically around 57lb-ft at 3000rpm.
In order to qualify for the under 1100cc class, some owners had their engines sleeved down by 1mm (effectively de-boring the cylinders to a 61.5mm diameter) for an overall displacement of 1099cc.
Another frequently used Ford engine of the time was the larger 1.5-litre overhead valve unit as fitted to the recently introduced Consul and Zephyr. Off the shelf, these motors displaced 1508cc thanks to a bore and stroke of 79.3mm and 76.2mm respectively. However, in order to contest the under 1.5-litre class, 9cc could be cut by eccentrically grinding the big end journals and fitting oversize bearings which effectively shortened the stroke.
Peak output of these 1.5-litre overhead valve Ford units once equipped with uprated SU carburettors and a higher compression ratio was typically 60-70bhp at 5000rpm to 6000rpm compared to 47bhp at 4400rpm in OEM tune.
To increase performance, buyers typically had their engines enhanced with aluminium cylinder heads, raised compression ratios, larger inlet valves, uprated valve springs and bigger carburettors.
If equipped with a Ford engine, transmission was normally through a three-speed gearbox sourced from the same manufacturer and many customers elected to fit a Buckler close-ratio gear set. As for the prototype, this initial 6 used a specially adapted four-speed Austin ‘box.
Another popular power unit with Lotus 6 buyers was 1.25-litre overhead valve XPAG unit from MG. In standard trim, these all-iron motors displaced 1250cc thanks to a bore and stroke of 66.5mm and 90mm respectively. They ran an 8.1:1 compression ratio, two SU carburettors and developed a peak output of 57.5bhp at 5500rpm and 65lb-ft at 3000rpm. If so equipped, a matching four-speed MG gearbox was usually installed.
BODYWORK
In terms of its body design, the 6 emerged as a fairly straightforward evolution of the minimalist lightweight theme that Chapman had developed with his Austin-based specials during the years prior.
At the leading edge of the central fuselage was a square-ish intake that left much of the suspension and brake assemblies exposed. If fitted, free-standing headlights and indicators were usually mounted atop the spring / damper units although some early examples came with the headlights located inside the nose aperture and indicators mounted atop the wings.
Despite having been comparatively narrow at its leading edge, the fuselage broadened out sufficiently that two occupants could be accommodated side-by-side in the cockpit. Ahead of the driver was an aerodynamically profiled air deflecting cowl. A conventional aluminium-framed windscreen was offered as an optional extra.
Engine cooling vents were typically located down each flank along with a 2-to-1 exhaust that could exit on either side depending on what motor was fitted. A detachable engine cover was normally left unvented although some cars were created with cutaways for carburettors while others came with fresh air scoops and even power bulges if clearance was a problem.
Located just behind the cockpit and fully integrated with the closely cropped tail were full width partially enclosed rear wheel spats. Normally, a spare wheel was mounted out back while up front, skimpy cycle wings were usually adopted although some cars instead came with bigger clamshell-style units.
Body panels for the stubby little car were fashioned exclusively from aluminium by Williams & Pritchard in Edmonton, north London.
Most buyers elected to keep their cars in an unpainted finish to save weight.
INTERIOR
As you would expect from a super lightweight vehicle of this nature, the 6’s cockpit was extremely spartan with many of the tubular steel chassis members left on show.
Instrumentation had to be sourced by the customer but typically located on the simple black aluminium fascia were large read outs for engine and road speed along with smaller dials for oil pressure, water temperature and battery amps plus a small number of flick switches and warning lights. Steering wheels were generally sourced from the donor car.
Upholstery (normally in plain black or red with white piping) was limited to the seat backs and bases. The seat backs themselves were removable for access to the rear axle while most cars also featured basic side trim panels mounted to the rear sidewalls alongside the seats. Otherwise, the floors, rest of the sidewalls and transmission tunnel were kept bare.
OPTIONS
From launch, Lotus offered the 6 with an array of optional extras that enabled customers to purchase a more complete machine as opposed to a simple chassis / body unit (which itself could be ordered either naked or fully skinned).
In addition to the aforementioned independent front suspension kit, Panhard rod and coil spring / damper units, the shortened torque tube / prop shaft and fuel tank, buyers could request a modified brake linkage, steering column and brake assemblies, a radiator, an upholstery kit, a windscreen and a hood complete with sidescreens.
Williams & Pritchard could also carry practically any degree of customisation; at least one customer ordered their 6 with a fully enveloped body while others requested an even more basic set-up for trials use. Trials versions came with a shorter, narrower fuselage, higher ground clearance, a solid beam front axle located by Panhard rod, long-travel suspension, higher seat positioning plus an engine mounted higher and further back in the chassis.
WEIGHT / PERFORMANCE
Weight and performance figures varied from car-to-car depending on the mechanical specification and state of tune. In 40bhp 1172cc Ford Sidevalve trim complete with upholstery kit, windscreen and hood, a Lotus 6 tested by Autosport in 1953 tipped the scales at 432kg, had a top speed of 88mph and a 0-62mph time of 12.7 seconds.
PRODUCTION CHANGES
Early on, Lotus made some modifications to the chassis bracing around the radiator zone.
In 1953, hydraulic brakes came on stream having been introduced on the Ford 100E.
1954 saw the fully enclosed rear wheelarches ditched and some changes made to the car’s rear bodywork. Wire wheels were also offered having been developed for the Lotus 8.
Mid way through 1954, MG released the TF 1500 with an enlarged 1.5-litre XPEG engine that proved a popular option for Lotus 6 buyers. Bored from 66.5mm to 72mm (for an overall displacement of 1466cc), in standard trim these motors featured an increased compression ratio (now 8.3:1) along with a peak output of 65bhp at 5500rpm and 76lb-ft at 3000rpm.
The arrival of the Lotus 9 in 1955 enabled Lotus 6 buyers to uprate their car with backplate-less twin leading shoe radial-finned magnesium drum brakes.
That same year, some owners began to fit Lotus 9 running gear to include the aluminium-cased Coventry Climax FWA motor hooked up to an MG four-speed gearbox. These recently introduced power units featured a cast iron block with a light alloy single overhead camshaft head and displaced 1098cc thanks to a bore and stroke of 72.4mm and 66.6mm respectively. With a 9.8:1 compression ratio and two 1.5-inch SU H4 sidedraught carburettors, peak output was 75bhp at 6100rpm and 68lb-ft at 5000rpm.
Certain BMC components had also begun to come on stream along with an updated rear suspension layout that comprised two upper parallel links which connected the axle to the chassis longitudinally while an A-frame picked up on the differential casing to restrict sideways movement and torque twist.
END OF PRODUCTION
Following completion of the prototype, Lotus 6 production ran from late 1952 until early 1957.
During this time, somewhere between 90 and 110 examples were produced. This figure included a handful of factory built competition cars that featured de Dion rear ends, Elekton wheels with integral drum brakes and the Coventry Climax FWA engine.
The Lotus 6 was ultimately replaced by the 7 Series 1 in September 1957, by which time Lotus had already gone on to offer the 8, 9 and 10, all of which were comparatively advanced (and expensive) sports racing cars capable of winning at international level.
COMPETITION HISTORY
The Lotus 6 prototype made its competition debut at the MG Car Club race meeting at Silverstone on July 5th 1952 where Colin Chapman placed second in the Unlimited Handicap (to Peter Gammon’s MG Special) while Michael Allen took second in the Novice Handicap (to J Beckwith-Smith’s Frazer Nash).
Off the back of this showing, Phil Desoutter placed an order for a production version.
Next up, Nigel Allen won the Aston Martin Owners Club Relay at Silverstone on July 27th and picked up a third place finish in the Handicap event.
Unfortunately though, when Nigel Allen was en route to the Boreham International meeting on August 2nd, chassis L176/1 was hit by a bread van and written off.
No more racing took place until 1953 when the works car of Colin Chapman, the rebuilt prototype of Nigel Allen along with the customer machines of Phil Desoutter and F.C. Hill collected 19 first place finishes between them with Chapman’s own car remaining unbeaten.
Over the next couple of years, the Lotus 6 remained the car of choice for all manner of circuit races, sprints and hillclimbs.
Text copyright: Supercar Nostalgia
Photo copyright: unattributed & H&H Auctions - https://www.handh.co.uk/
