Introduced in 1925, the Phantom I 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 and the New Phantom was renamed Phantom I.
One major improvement over the Silver Ghost was the new pushrod-OHV straight-6 engine. Constructed as three groups of two cylinders with detachable heads, the engine was described by Rolls-Royce as producing "sufficient" power. The engine used a 4¼in (107.9 mm) bore and undersquare 5½in (139.7 mm) stroke for a total of 7.7 L (7,668 cc (467.9 cu in)) 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.
The New Phantom used the same frame as the Silver Ghost,with semi-elliptical springs suspending the front axleand cantilever springs suspending the rear axle. 4-wheel brakes with a servo-assistance system licensed fromHispano-Suiza were also specified,though some early US models lacked front brakes.
Differences between US and UK versions
Like the Silver Ghost, the Phantom was constructed both at Rolls-Royces' Derby factory in the United Kingdom and at a factory in Springfield, Massachusetts in the United States. The US factory produced Phantom Is from 1926 to 1931.Most UK Phantom I's retained the fuel gauge at the tank, but some US models had one on the dash. The UK Phantom retained oil lubrication through Enots nipples, some times as many as 50, which attached to a special Enots oil pressure gun and needed to be attended to regularly at 500, 1000 and 2000 mile intervals, involving much time and effort. The US Phantom used a Bijur centralized oiling system which connected all the oiling points and oiled them with a stroke of a single pump.
Other differences between the US and UK models included available wheelbases and transmissions. Both versions were specified with the same 143½in (3644.9 mm) standard wheelbase, but the UK long-wheelbase model was longer at 150½ (3822.7 mm) than the 146½in (3721.1 mm) American version. UK models used a 4-speed transmission while US models used a centre change 3-speed transmission,both with a single dry-plate clutch.
Only the chassis and mechanical parts were made by Rolls-Royce. The body was made and fitted by a coachbuilder selected by the owner. Coachbuilders who produced bodies for Phantom I cars included Barker, Park Ward, Thrupp & Maberly, Mulliner and Hooper. American Phantoms could be bought with standardized bodies from Brewster & Co., which was owned by Rolls-Royce .
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