Background
Sir Donald Campbell, the land speed record hero, owned a Rolls-Royce 20/25.
Need we say more?
Yes? Okay then.
The 20/25 was introduced in 1929, its name denoting the new model had the Twenty’s chassis with a larger and more powerful 25hp 3.7-litre engine. A 1931 Autocar magazine report describes the 20/25 in glowing terms: “Every single feature spells durability, the machine is on a plane altogether superior to the normal style of motor car'.”
It was a very popular, if expensive, motorcar going on to sell 3,827 examples in all, a staggering 70% of which are thought to still be on the road: Quality engineering might not be cheap, but it is usually good value.
And it is very well engineered: The 3699cc straight-six features overhead pushrod operated valves and a cast-iron block with an aluminium crankcase. A single cast iron cylinder head sits atop the assembly and the long-stroke design incorporates a seven-main-bearing crankshaft with a vibration damper and pressure-fed lubrication, with a relief valve feeding the rocker shaft and timing gears.
Mated to this is a four-speed manual gearbox with synchromesh on third and fourth gears, and a single plate dry clutch. Servo-assisted brakes on all four wheels ensure it pulls up smartly from the sort of high speeds it is capable of, and the specification was enhanced in 1932 by the addition of modern dampers and a thermostat-controlled cooling system. The latter controlled the airflow through the radiator automatically, eliminating the need for the driver to open and close the radiator shutters by hand.
All 20/25s were supplied as a running chassis to coachbuilders such as Park Ward, Vanden Plas, Hooper, Freestone and Webb, Brewster, Gurney Nutting, Thrupp & Maberly, Mulliner, and Rippon Bros.
The 25/30 superseded it in 1936.









