1936 Bentley 3.5 Liter

Bentley Motors was acquired by Rolls-Royce in 1931, robbing it of its independence but ensuring the company's survival. The first of what would become known as the 'Derby Bentleys' arrived in 1933, continuing to build upon the company's reputation for sporty and refined motoring.

The 3.5-Liter (3,669cc) Bentley was based on the contemporary Rolls-Royce 20/25hp, but with a slightly shorter wheelbase and powered by an overhead-valve six-cylinder engine with twin SU carburetors and delivering 115 horsepower. It was joined by a four-speed manual gearbox containing synchromesh on the top two ratios, a single dry plate clutch, and servo-assisted drum brakes. The suspension was by semi-elliptic leaf springs all round.

The 3.5-Liter Bentley long-distance tourer offered effortless sports car performance in nearly absolute silence, earning it the nickname, 'The Silent Sports Car.' It successfully combined the refinement of the Rolls-Royce with the performance and handling of the Bentley.

Production
The Bentley 3½ Litre was an exclusive, coachbuilt automobile with total production reaching 2,442 units (including the subsequent 4.25 Liter model; production of the 3.5-Litre continued into 1937, by which time 1,191 (as few as 1177) examples had been produced), with nearly half receiving coachwork by Park Ward in a limited number of styles. The last year's allocation was manufactured alongside the incoming 4.25-liter (4257cc) version that would ultimately supersede the 3.5-litre cars. The MX-series of 1939 was the final iteration of the model. The Series A to F were 3½ Litre cars; G to L (with the exception of I) were 4¼ Litres, and the M series was the 4¼ Litre Overdrive chassis. Each series had 100 chassis numbers, with the numbers 13 and 113 being excluded due to superstition.

The series was replaced in 1939 by the MKV, but some examples were still delivered as late as 1941.

Coachbuilders
The list of coachbuilders who clothed the 3.5-Liter includes Park Ward, Vanden Plas, Barker, Hooper, Windovers, James Young, Arthur Mulliner, Thrupp & Maberly, Gurney Nutting, Figoni et Falaschi, Kellner, Saoutchik, Vanvooren, Carlton, Rippon Bros, Mann Egerton, and H.J. Mulliner.

Many of the bodies were built from aluminum which was lighter and more expensive than steel.

The Engine
The 3,669cc inline six-cylinder engine had a 3.25-inch bore and a 4.5-inch stroke. Developed from Rolls-Royce's straight-6 powering the 20/25, it had a higher compression ratio, two SU carburetors on a crossflow cylinder head, and a sportier camshaft. It developed 110 horsepower at 4,500 RPM, giving the Bentley a top speed of around 90 mph, depending on coachwork.

Mechanical Specification
The Bentley 3.5 Litre had 126-inch wheelbase chassis was manufactured from nickel steel, with a 'double-dropped layout. Inherently strong, the chassis did not require additional diagonal cross-bracing, allowing it to weigh less than most of its contemporary competitors. The suspension was via leaf springs, and four-wheel servo-assisted mechanical brakes provided the stopping power. The four-speed manual transmission had synchromesh on the 3rd and 4th gears.

The Bentley 4¼ Litre
Bentley introduced its 4¼ Litre replacement for the 3½ Litre model in March of 1936. It had an enlarged bore of 3.5 inches for a total displacement of 4,257cc (4.3 liters). The MR and MX series of 1938 had Marles steering and an overdrive gearbox.

A total of 1,234 examples of the 4¼ Litre cars were built, with Park Ward continuing to cloth the lion's share.

by Daniel Vaughan | May 2023