Bristol 406S: last roll of the straight-six dice

By Martin Buckley

| 11 Sep 2024

Classic & Sports Car – Bristol 406S: last roll of the straight-six dice

Under Sir George White and Anthony Crook, production of Bristol cars post-1961, while less ambitious in numbers, was more settled and linear in character.

Their formula was a simple one: progressively greater power and more luxury features in a long and distinguished line of three-volume, Chrysler V8-powered two-door saloons of variously handsome, bland or somewhat eccentric appearance, intended as ‘dignified travel for four six-foot people and their luggage’.

These American-engined and exclusively automatic vehicles were handmade, to order, in very small numbers for a local and almost entirely right-hand-drive market, and only distributed from the famous showroom on Kensington High Street, London.

The Bristol 406S got four-wheel Dunlop disc brakes

The 1946-’60 six-pot cars had emerged from an ethos that was working towards serious volume production.

They were available from a variety of regional Bristol distributors and built in larger quantities and in a wider variety of shapes and sizes than the 407 to 411 (and beyond) V8s: two doors or four, open or closed, and on standard or shortened versions of the famous box-section chassis.

Built for export and home delivery, they appealed to customers who engaged with the process of driving as an enjoyable activity and were relatively insensitive to the high initial cost, but expected their cars to work for a living and do the miles unfailingly, given reasonable attention to servicing.

The Bristol’s 130bhp ‘BB6’ engine has been swapped for a standard 2.2-litre unit

Building on this reputation, the works sought to extract maximum value from the pre-war BMW road-car technology it had acquired as the spoils of war in 1945.

The Munich-built cars had been among the most advanced of the ’30s; post-war development potential was abundant.

By the mid-1950s, Bristol not only boasted a competition department – fielding the odd-looking but effective 450 sports-racer – but was also offering four different road cars: the 403, 405 saloon, 405 drophead and the short-chassis 404.

It was even supplying engines to AC.

‘It makes all the right thoroughbred noises: a sonorous blend of busy-sounding valvegear and lusty induction roar’

Yet by 1951, car production had peaked.

Tellingly, the original, mostly steel-panelled 1947-’50 400 was the most prolific of the early Bristols, with 700 built, followed closely by the 401 and 403.

The construction method, based on a chassis with deep box-section side members, lent itself to specialist coachwork, so production figures were supplemented at various times by small quantities of Farina, Touring and Bertone-bodied variants (the latter producing a run of short-chassis Arnolt-Bristols), plus occasional one-offs by the likes of Abbott and Beutler.

The Bristol 406S has tailfins for streamlining, rather than for style

The aluminium-bodied 2-litre Bristol was beautifully made, in the highest-quality materials, and its responsive cross-pushrod straight-six, delightful gearbox, sensitive rack-and-pinion steering and accurately located live rear axle made it a machine for wealthy connoisseurs in an initially product-hungry UK market.

But as the ’50s unfolded, this market was not only increasingly well served by a new generation of monocoque-construction Ford, BMC and Vauxhall six-cylinder saloons – with comparable urge, if not behaviour, for vastly less money – but also dominated by the value, visual appeal and performance of Jaguar’s MkVII/VIII/IX saloons and the compact 2.4.

Well aware of these developments in the background, Bristol’s designers were working on a completely in-house model: a car that, it was hoped, would complete the transition from small-scale manufacturer of expensive, specialist 2-litre models to a maker of much larger-engined luxury cars with more effortless performance.

The Bristol 406S has an airy cabin, with comfortable seats and a great driving position

This would be a Bristol that could challenge Jaguar in a section of the market the Coventry firm was increasingly making its own, while keeping abreast of customers’ expectations in terms of power and the sort of luxury features that inevitably added weight.

The fate of Project 220 was tied in with both the fortunes of Bristol as an aircraft maker and the wider British aero industry, which by the end of the 1950s was under serious pressure from the government to merge.

In 1959, Bristol Aero Engines and Armstrong Siddeley engines would join forces to form Bristol-Siddeley.

This move not only triggered the demise of Armstrong’s car-making activities, but also brought the company’s 4-litre straight-six into Filton’s orbit as a possible alternative to its own 2-litre engine – yet it was soon identified as being too big and heavy, and lacking the crisp response of the Bristol unit

The Bristol 406S was influenced by the Beutler 406E of 1957

From a position of leadership in the post-war years, having invented the jet engine, the very public Comet air disasters had set back the British aerospace industry significantly.

BOAC’s refusal to accept deliveries of the Bristol Britannia until further checks had been made caused stockpiles of aircraft and cashflow problems that nearly bankrupted the firm.

As detailed by marque historian Christopher Balfour and others, so began a chain of events that led to the acquisition in 1960 of the firm’s car-making operation by White and Crook.

First, by splitting (in 1956) the firm’s various activities into separate aircraft, aero-engine and car divisions, each was protected from shortfalls inherent in the parent company.

The Bristol badge on the six-cylinder 406S

Yet there was no question of spending money on developing an all-new design such as the 220, with its 3.7-litre, all-alloy straight-six and Alex Moulton’s Flexitor rubber springing.

Car-making activities could no longer assume to be supported by the aeronautical side.

Shunted into the light-engineering works, Bristol Cars even had to get an agreement from the engine division that it would keep making the old BMW ‘six’, at least for the time being.

As the Filton board mused on how best to shut down the car division, plans were afoot to introduce a two-door successor to the 405 that was to be the last six-cylinder Bristol model – and could easily have been the last Bristol car of any type.

The Bristol’s tailfins appear less pronounced from the rear than they do when seen from the side

It was to be fitted with a longer-stroke, 2.2-litre Type 110 development of the cross-pushrod straight-six, along with four-wheel Dunlop disc brakes, overdrive and a Watt linkage to provide improved sideways axle location and a lower roll centre.

Enter, in 1958, the 406: a more formal two-door saloon that was to set Bristol’s styling agenda for almost the next 20 years.

Following the government-led reorganisation of the aircraft industry, the car division of the Bristol Aircraft Company then suffered another setback when it lost its body-building facility.

As a result, it was forced to subcontract the manufacture of the 406 saloon bodies to Jones Bros of Willesden.

Bristol designer Dudley Hobbs is credited with the 406S shape

Included in the run of 171 production 406s were six Zagato-bodied cars (instigated by Tony Crook) and the one-off, factory-bodied 406S pictured here: a purposeful-looking two-seater that in many ways represents the Bristol ‘six’ in its ultimate form as a road car.

Once again Hobbs, assisted by Dennis Sevier, is credited with the shape, adapted from the 404 but longer and better balanced in profile than the slightly stunted 1953-’55 two-seater.

Like the saloon it had vestigial tailfins, which were supposedly more for aerodynamic than stylistic effect.

The grille treatment was as per the early 406, with vertical bars and quarter-bumpers – both features now lost on the car as it appears today with specialist SLJ Hackett.

406 CHU with early grille treatment and corner bumpers

The trademark wing bays (for the battery and spare wheel) plus additional indicators on the roof like the standard 406 (and early FX4 Austin taxis) remain.

Adoption of a 9ft wheelbase, slightly longer than the 404 and Arnolt-Bristol chassis, plus the Watt linkage from the standard 406 saloon, also cured the instability issues inherent in the earlier cars.

Chassis SP1 received a 130bhp sports version of the 2.2-litre engine, one of the ‘BB’-series of six (BB2-BB7) as used in the Zagato-bodied cars.

A 100F sports cam was supplied by Anthony Crook Motors Ltd, with adjustments to the carb, distributor and compression ratio, and strengthening of the camshaft journals.

The Bristol 406S has round tail-lights with chrome surrounds

Bristol’s loss of its in-house body-making capability meant a strict one-model policy, so the future of the 406S was probably settled before this prototype was even complete.

Registered 406 CHU, chassis SP1 was purchased from Bristol Cars Ltd by Crook in June 1958 and used by him as his day-to-day car until 1961.

It was delivered to Crook in Cambridge Grey with green lizardskin upholstery.

After covering some 70,000 miles in the managing director’s hands, the 406S was sold to a vet, who is thought to have added another 500,000 miles from his base in Aberdeen.

‘As the board mused on how to shut down the car division, plans were afoot to introduce a two-door successor to the 405’

In the mid-1960s, 406 CHU was fitted with the standard 2.2-litre engine that it retains to this day.

The more potent BB6 unit was later rebuilt and installed by the factory into the prototype 405 saloon.

In the early ’90s, chassis SP1 was discovered as a collection of parts (in three locations) and bought back by Bristol Cars.

After rebuilding the one-off, Bristol passed the ‘S’ to collector Simon Draper in 1994; it was then sold on and recommissioned again in the mid-2000s.

The Bristol 406S has a well-balanced profile, only interrupted by the roof-mounted indicator lights

More recently, it has had its fuel and braking systems rebuilt, new tyres and exhaust fitted, and various missing chrome parts recreated, but not the quarter-bumpers visible in the (few) surviving period pictures.

Inside, it is light and bright, with a traditional Bristol instrument nacelle and a comfortable driving position that suggests attention has been paid to how legs articulate rather than treating you as an inconvenient afterthought.

The front seats recline and have additional pop-up shoulder supports in the tops of the backrests: an airliner-type refinement shared with the 406 saloon, but not found on the V8s.

The Bristol 406S is agile and neutral, with light steering

To start it, you first turn the key then push a button.

With its trademark angled valve covers and handsome manifolding, the responsive, throaty ‘six’ sits tall and narrow between the chassis rails, its ball-jointed rigid throttle linkage allowing millimetric control.

Bristol experimented with SU carburettors, but triple Solexes gave a better response.

You can blip accurately coming down the ’box and feed in just the required amount of power, then allow the revs to wind out crisply: 5000rpm gives 60mph in second and nearly 90mph in third.

Stock dials in the classic Bristol’s busy dashboard

It is vocal when roused, but makes all the right thoroughbred noises: a sonorous blend of busy-sounding valvegear and lusty induction roar.

Being a standard 406 engine, this 2.2-litre is equally content to burble along at 2500rpm in direct top, dipping in and out of overdrive as conditions and mood dictate.

The ride is firm, but the car feels of-a-piece in a way that is rare with body-on-frame vehicles, so bumps don’t cause rattles.

The impression is of refinement.

Adjustable chairs make it easy to get comfy in the Bristol 406S

Both the steering and gearchange are sensual delights.

The former is light and nicely geared, at three turns between tight locks, and it has none of the low-speed heft and straight-ahead slop that characterises most big ’50s cars.

Via a handy shifter, the gears slice through quickly, quietly and precisely between well-chosen ratios to keep the engine on the boil.

It handles tidily, neutrally and accurately, encouraging spirited progress and rewarding well-coordinated inputs from your hands and feet.

The 406S never feels fazed or unsettled by any kind of corner or surface.

Livelier than a standard 406, lovelier (to my eyes) than the 404, this must surely be the ultimate roadgoing six-cylinder Bristol, with the possible exception of the short-chassis 406 Zagato.

Images: John Bradshaw

Thanks to: SLJ Hackett

Factfile

Bristol 406S

Sold/number built 1958-’61/171 (all 406s)
Construction aluminium body over tubular steel frame, steel box-section chassis
Engine iron-block, alloy-head, ohv 2216cc straight-six, triple Solex carburettors
Max power 130bhp @ 5750rpm
Max torque 132lb ft @ 3000rpm
Transmission four-speed manual, RWD
Suspension: front independent, by wishbones, transverse leaf spring rear live axle, longitudinal torsion bars, transverse links; telescopic dampers f/r
Steering rack and pinion
Brakes discs
Length 14ft ¾in (4286mm)
Width 5ft 8in (1727mm)
Height 4ft 7in (1397mm)
Wheelbase 9ft (2743mm)
Weight 2296lb (1041kg)
Mpg 26-30
0-60mph n/a
Top speed 125mph (est)
Price new £4244 (standard 406)
Price now £295,000*