The Rolls-Royce Phantom was Rolls-Royce's replacement for the original Silver Ghost. Introduced as the New Phantom in 1925, the Phantom had a larger engine than the Silver Ghost and used pushrod-operated overhead valves instead of the Silver Ghost's side valves. The Phantom was built in Derby, England, and Springfield, Massachusetts, in the United States. There were several differences in specification between the English and American Phantoms. The Phantom was replaced by the Phantom II in 1929. The designation Phantom I was never used by Rolls-Royce; it is a construct of enthusiasts applied to help distinguish it from other generations with the same model name. Description Name Introduced in 1925, the New Phantom was Rolls-Royce's second 40/50 hp model. To differentiate between the 40/50 hp models, Rolls-Royce named the new model "New Phantom" and renamed the old model "Silver Ghost", which was the name given to their demonstration example, Registration No. AX201. When the New Phantom was replaced by another 40/50 hp model in 1929, the replacement was named Phantom II and the New Phantom was commonly referred to as Phantom I to this day. While Rolls-Royce themselves did not use the term Phantom I until their recent acquisition by BMW Group, New Phantoms were referred to as such in period and are commonly called Phantom I by enthusiasts, concours events, and owner's clubs. Drivetrain One major improvement over the Silver Ghost was the new pushrod-OHV straight-6 engine. Constructed as two groups of three cylinders with a single detachable head, the engine was described by Rolls-Royce as producing "sufficient" power. The engine used a 4¼ in (107.9 mm) bore and undersquare 5½ in (139.7 mm) stroke for a total of 7.7 L () of displacement. In 1928, the cylinder heads were upgraded from cast iron to aluminium; this caused corrosion problems. The separate gearbox connected through a rubberised fabric flexible coupling to the clutch and through a torque tube enclosed drive to the differential at rear, as in the Silver Ghost. Chassis The New Phantom used the same frame as the Silver Ghost, with semi-elliptical springs suspending the front axle and cantilever springs suspending the rear axle. 4-wheel brakes with a servo-assistance system licensed from Hispano-Suiza were also specified, though some early US models lacked front brakes. Differences between US and UK versions Like the Silver Ghost, the New Phantom was constructed both at Rolls-Royce's Derby factory in the United Kingdom