1939 Bentley 4¼ Liter

Walter O. Bentley's company was purchased by Rolls-Royce, Ltd. in 1931 and moved from Cricklewood, London to Rolls' Derby works. The Bentley cars produced from 1933 through 1939 are known as the 'Derby Bentleys.' The first of these was based on the current-series Rolls-Royce 202/25-horsepower chassis but was reconfigured to use the 20/25's 2.75-liter engine. The 126-inch bare chassis left the factory to be bodied by outside coachbuilders.

By 1936 the bodies had grown in size and weight and a new power plant was required. To provide more horsepower, a 4257-cc engine was offered, complete with a higher compression ratio of 6.8:1 compared to 6:1, and the Rolls-Royce Stromberg downdraft single carburetor was replaced by dual SUs. A few of the 3.5-liter cars were converted at the factory to the larger power plant. With permission from Hispano-Suiza, servo-assisted mechanical brakes were placed on all four corners of the car.

The new 4.25-Litre (4,257cc) model, introduced in 1936, had an increase in power over the previous model while retaining the well-proven chassis with servo-assisted braking and faultless gear-change. This new engine was shared with the equivalent Rolls-Royce, the 25/30hp, and as had been the case with the preceding 3½-Litre model, was a superior specification in Bentley form, fitted with twin SU carburetors, raised compression ratio, and a more 'sporting' camshaft. Equipped with twin SU carburetors, the 4,257cc overhead valve inline 6-cylinder engine delivered 126 horsepower at 4,500 RPM. The introduction of the Hall's Metal bearings would eventually lead to an adoption of an overdrive gearbox and improved lubrication system, improvements which coincided with the introduction of the 'M' series cars in 1939. Approximately 200 examples were produced during 1939 (a total of 1,234 examples during its production lifespan), and they were renowned for their reliability, refinement, and long-distance cruising capabilities.

The 126-inch wheelbase platform was suspended at the front via a solid axle with semi-elliptical leaf springs and hydraulic shock absorbers. At the rear was a live axle setup with semi-elliptical leaf springs and hydraulic shock absorbers. Servo-assisted mechanical drum brakes at all four corners provided the stopping power. Most examples wore coachwork by Park Ward and most were formed from steel rather than the previous, aluminum over ash frame construction.

The new 4¼-Litre model delivered more power than before while retaining the finely tuned chassis with faultless gear-change, and servo-assisted braking. 'The Silent Sports Car', as it was quickly dubbed, had few peers as a tireless long-distance tourer

by Daniel Vaughan | Sep 2019