The Bristol 403 – a car built by aircraft makers

Bristol was perhaps the most enigmatic and exclusive company in the post-war motor business. Using aircraft building expertise it made the finest sporting cars in the world for the most discerning gentlemen (and lady) owners.

Bristol Cars had only one showroom, in Kensington, London, and the company gave a general impression that it didn’t really want to sell its cars to just anybody.

To such consummate engineers, the buying public was a bit of a nuisance. But to some, owning a Bristol car was to be part of a cult.

A green Bristol 403 at the factory in Bristol, England where they made them
A Bristol 403 at the factory in Bristol, England where they made them

The first Bristol model was the 400. This was the first car to come out of Bristol Cars Limited just after the end of the Second World War, but it was a direct copy of the best pre-war German cars from BMW: the chassis was based on the BMW 326, the body on the 327, and the engine on the 328. It was sold between 1947 and 1950.

So why were these subtle, tasteful and unostentatious luxury cars bought by larger-than-life celebrities such as Bono, Liam Gallagher and Sir Richard Branson? And how was Bristol allowed to copy BMW with their first car, the 400?

Read on to find out more…

The Bristol Aeroplane Company, founded in 1911 was one of Britain’s best aircraft manufacturers, eventually being responsible for Concorde.

During the First World war, they made excellent biplanes such as the Bristol Fighter, but after the Armistice, they were suddenly faced with a collapse in orders. After a struggle, they managed to diversify into car and bus production.

Later in the 1930s came the Bristol Bulldog fighter, and aircraft engine production. When war broke out again in 1939, the Bristol aircraft factory at Filton was the biggest in the world. During the war, they built the Bristol Beaufighter, a twin-engined long-range fighter and torpedo bomber, and thousands of powerful air-cooled radial engines for bombers.

After the Second World war, the management wanted to avoid the same financial difficulties and dramatic loss of orders they had suffered after the First World war, so they decided to diversify into car production.

Plans had been drawn up well before peacetime to build a Bristol car at Filton to keep some of the 50,000-strong wartime workforce occupied when the military contracts ended. There was no time to develop their own car design, and so it was decided to base the new Bristol car on an existing design.

Bristol went into brief alliance with AFN Ltd owner HJ Aldington. He had made chain-driven Frazer Nash sports cars before the war and had been the official British BMW importer. During the war AFN had made gun turrets for Bristol aircraft such as the Blenheim Mk. IV and Beaufort, hence the business relationship with the Bristol Aircraft company.

The high quality of the 700 or so BMW cars Aldington had sold in England before the war had been well understood by anyone with a feel for efficient, fine-handling cars. Bristol started to examine the possibility of making BMW cars under licence.

Aldington’s contacts with BMW’s German managers and engineers – many of whom were in Allied jail – enabled Bristol to acquire the plans and rights for the firm’s pre-war range.

The body of a green Bristol 403 cut away to show the aircraft-quality construction of a Bristol car.
The Bristol construction was to aircraft standards. Here is a later 403 at the Filton museum.

Remember, too that as a result of war reparations the German nation had to make amends for the damage done to the Allied nations. To the victor, the spoils!

So Bristol was able to purchase the rights to manufacture a design based on the BMW 326 saloon, 327 coupe and 328 sportscar (source: wikipedia).

A grey A BMW 328
A BMW 328

The BMW 326 was a good choice of chassis, as this car was a highly-regarded saloon released at the 1936 Berlin Motor Show, and designed by the talented Fritz Fiedler. It featured an aerodynamic four-door body mounted on a box-section chassis enabling different bodies to be fitted.

It had a torsion bar rear suspension inspired in turn by the Citroën Traction Avant. Car makers are great copiers of other designs!

The Bristol 400 also copied the BMW 328’s M328 engine, an unusual and powerful design by Rudolf Schleicher. It had six cylinders with a total capacity of 1,971 ccs or 120.3 cu in. This engine had a particularly interesting valvetrain design.

BMW wanted to build a 2-litre car that could compete in international racing. The company knew the engine should have a true double overhead camshaft (DOHC) design, with hemispherical combustion chambers and overhead valves in a V shape.

However, the company did not have enough money. So they had to use their existing six-cylinder engine with its conventional side-mounted camshaft and overhead valves.

So a clever design solution was dreamt up that many engineers thought was totally impracticable, but which vindicated its design through many production and racing successes.

Although the camshaft was in the conventional place, running low in the cylinder block and operating the valves by long pushrods, the exhaust valves were opened by extra short pushrods running across the head, pushed by extra bell cranks.

This design enabled the engine to have the desired hemispherical combustion chambers, with the inlet and exhaust valves inclined like a double overhead camshaft design (DOHC). Furthermore, the inlet passages were vertical, entering the cylinder straight between the inlet and exhaust valves (source and drawings:

This meant that the three downdraft SU carburettors had a straight shot downwards, leading to great volumetric efficiency. The Bristol engine produced 80 hp at 4,500 rpm and could propel the Bristol 400 to 92 mph, with good acceleration. This was at a time, remember when most cars on the road struggled to maintain 50 mph.

This engine went on to power not only all the Bristol models until 1961, but also Lotus, AC, Cooper, Frazer Nash and Lister sports and racing cars.

A sectional view of a Bristol 403 showing parts under the bodywork including the engine.
The Bristol six-cylinder engine, seen here in a 403 car, had a unique valvetrain design.

The torsion bar rear suspension on the Bristol 400 was unusual, too. The first time you look under the back of a Bristol 400 you can’t fathom out what they’ve done (source:

The torsion bars ran forwards, parallel with the chassis members, their rear ends terminating in right-angled suspension levers. The rear axle hung on these, with a central A-frame to provide lateral location. Most car designs of the time used cart springs in this location, indeed lots of vans and trucks today still use these old horse-drawn era springs.

The underside of a Bristol car shows a black-painted rear axle and unusual torsion bar springs.
The Bristol used an unusual torsion-bar rear suspension.

As well as using the BMW blueprints, Bristol Cars were lucky to have the expertise of the original BMW designer, Fritz Fiedler. In 1947 Fiedler was persuaded to move to England and work for AFN Ltd.

He was lent by the Frazer Nash company to Bristol for consultancy work on the Type 400 project. Dr Fielder, as he was known was very popular with his English colleagues, who admired his engineering expertise and described him as a kind man, and charming.

Bristol made many improvements to the German design. They used aircraft levels of build quality which made the 400 better than its German older sisters. It was sharp to drive, it had zippy performance, it was quiet at speed, and thanks to excellent aerodynamics, it was fast for its relatively modest power output.

Everything was made in-house to exacting aircraft standards, including the door locks and the shock absorbers. Only the Borg & Beck clutch, the carburettors and the Lucas electrics were outsourced. Bristol 400s competed on the Rallye Monte-Carlo, the Mille Miglia and the Targa Florio.

At £2400, or £105,000 today this was a wealthy connoisseur’s machine (source: CPI Inflation Calculator). Before motorways the Bristol 400 was probably the fastest way to travel point to point in mainland Britain.

The word got out, though and all sorts of unlikely people bought Bristol cars- people such as the celebrities mentioned above, and also the UK’s best car journalist L.J.K Setright, who was evangelical on the subject of the Bristol 400. He stated unequivocally that the Bristol was the World’s Best Car (source: Motor Sport Magazine).

It was he who largely contributed to the Bristol cult, and as with most cults in the end the wrong people joined.

Stats: 0-60 mph: 15 seconds. Top speed: 95 mph. Weight: 1120 kg. 487 examples were made.

A grey A Bristol 603
A Bristol 603

Are Bristol Cars Still Made?

Bristol Cars are no longer made. The designs became increasingly eccentric and irrelevant, and after being placed in receivership and taken over in 2011 the company was liquidated in February 2020.

Perhaps they should have stuck to making BMWs.

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