1938 Rolls-Royce 25/30HP

During the early 1930s, Rolls-Royce produced a series of small-horsepower models known as the Twenty, 20/25, 25/30, and by the close of the 1930s, the Wraith. The company's 40/50 HP Silver Ghost earned the title of the 'Best Car in the World' and was in production for two decades, from 1906 to 1926, with 7,874 units built during that time. The straight six-cylinder engine initially displaced 7,036cc before growing to 7,428cc in 1910. The original three-speed manual was replaced in 1913 by a four-speed manual. The New Phantom followed in 1925 and would carry Rolls-Royce customers into the early 1930s, with 3,512 units built during its production lifespan. It had a larger engine than the Silver Ghost, with the 7,668cc unit using pushrod-operated overhead valves instead of the Silver Ghost's side valves. The Rolls-Royce Phantom II (the third and final 40/50hp model) arrived in 1992 and used an all-new chassis with an improved version of the Phantom I engine. The final large pre-war Rolls-Royce was the Phantom III, built from 1936 to 1936 with 727 units built.

The 20 HP of 1922 entered production during a period of market downturn following World War I. The company's use of a smaller model evolved into the 20/25 and finally to the 25/30 of 1936 to 1938. While the Phantom III rested on a 142-inch wheelbase (slightly less than the Phantom II), the 20/25's platform measured 132-inches and its 6-cylinder engine displaced 4,257cc, much smaller than the 7338cc V12 unit powering the Phantom III but slightly larger than the 3669cc unit found in the preceding 20/25hp. The more powerful 20/25 HP model helped compensate for the over-size bodies being built.

The 3,669cc pushrod operated valve engine had a bore size of 3.5-inches (changed from 3.25 inches) and a stroke of 4.5 inches (unchanged). The construction was by a separate cast iron block and aluminum crankcase with a detachable cast iron 6-plug head. It had pressure-fed lubrication, a seven-bearing crankshaft, and vibration dampers. It had 6:1 compression and a Stromberg downdraught carburetor. The four-speed manual gearbox was mounted in-unit with the engine with synchromesh on the third and top gears. The gearbox used a right-hand drive configuration. The riveted chassis, measuring 132 inches, had rigid axles and was suspended by hydraulic dampers and half-elliptic springs. The stopping power was courtesy of mechanical servo brakes on all four corners used under license from Hispano-Suiza.

Between 1936 to 1938, Rolls-Royce built 1,201 examples of the 25/30 HP. Rolls-Royce created the chassis and mechanical components while the coachwork was outsourced to various coachbuilders. Among the list of coachbuilders were Park Ward, H.J. Mulliner & Co., Arthur Mulliner, Thrupp & Maberly, and Hooper. Body styles included open tourers to formal limousines, built to individual specifications by their owner.

by Daniel Vaughan | Oct 2022