From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Article from 'The Automobile Engineer' magazine describing the Frazer Nash-B.M.W. 2-Litre Chassis.
| Identifier | ExFiles\Box 126\3\ scan0140 | |
| Date | 1st October 1936 | |
| Reprinted from THE AUTOMOBILE ENGINEER, October, 1936. THE FRAZER NASH-B.M.W. 2-LITRE CHASSIS. An Interesting Design with Tubular Frame and Independent Front Suspension. FOUR models of this interesting and somewhat unconventional little chassis are available, two fitted with a 1 1/2-litre power unit and two with a 2-litre engine, there being a touring and a sports variety of each type. The chassis is practically the same for all four models, while the design of the two engines is, save for dimensions, identical. That forming the subject of the following description is known as Type 45. Perhaps the most noticeable feature is the unusual frame construction with its tubular side-members placed far apart at the rear end, tapering to the narrow anchorage bracket for the independent front wheel suspension. This model is fitted with a 2-litre six-cylinder engine having overhead valves operated by push rods. The power is transmitted through a single-plate clutch to a four-speed gear box, and the drive is then continued through an open propeller-shaft to a spiral bevel rear axle of the semi-floating type. The rear axle ratio is on the high side, though naturally the sports model is higher still. The power/weight ratio is good, a considerable saving in weight being accounted for by the unusual frame construction. This has also helped to furnish a low centre of gravity, which, combined with the form of suspension adopted, has resulted in unusually good road-holding qualities. Of German origin, the Frazer Nash-B.M.W. chassis is assembled at the works of A.F.N., Ltd., London Road, Isleworth, the intention being to manufacture them there in the near future. While left-hand steering is shown in the accompanying illustrations, every chassis emanating from the British works has the steering on the right. As has been found on certain American cars, this conversion is not always a simple matter, but in this instance certain parts were carefully redesigned in the drawing office of the B.M.W. company, with the result that there is no suggestion of makeshift fittings. The cars sold in Britain present every aspect of being originally designed for right-hand steering. Engine. Remarkable smoothness and high output is claimed for the engine, a maintained brake-horse-power of 45 being obtained at 3,800 r.p.m., an extra 10 b.h.p. being developed on the sports engine, which has three carburettors with semi-downdraught ports, compared with two on the model illustrated. The bore and stroke are 65 mm. and 96 mm. (approximately 2.56in. by 3.78in.), giving a swept volume for the six cylinders of 1,911 c.c., and an R.A.C. rating of 15.71 h.p. (tax £12). The six cylinders are cast en bloc with the upper half of the crank case, a detachable head being fitted. Both are in special close grain seasoned iron. A light steel pressing is employed for the lower half of the crank case. Generous water spaces are provided round the cylinder bores, an impeller-type water pump being incorporated in the fan bearing housing. The little rotor is a particularly neat aluminium die casting. The radiator is fitted with thermostatically operated shutters. Aluminium alloy pistons of the split-skirt type are fitted, having a strong flat crown well supported by tapering ribs. They are a German proprietary piston known as Nüral. Two gas rings are fitted, and beneath this is a special ground scraper ring of channel section, with the open side outwards, while the base is pierced by a series of holes machined with a circular cutter, thus providing plentiful venting of the scraped oil. Of H-section, the connecting rods are stampings in heat-treated steel, the small ends floating on the hollow gudgeon pins, which are located in the piston bosses by a circlip at each end. A phosphor-bronze bush is fitted in the small end, while white metal bearings are cast into the big ends, each cap being retained by two studs. A noticeable feature is the fact that the central web of the H-section of the connecting rod is thickened up and drilled for positive lubrication of the small-end bearing. A Chrome-Vanadium forged steel crankshaft is employed, mounted in four white metal bearings. Large lightening holes are formed in the crankshaft, the webs being drilled diagonally for lubrication purposes, a tube being inserted to carry the oil through the lightening holes. The shaft is dynamically balanced, and at the front end a parallel extension carries a small sprocket for the camshaft chain drive, a pressed-steel oil thrower, and, outside the timing case, the driving pulley for the fan belt and starting handle claw. The starting handle claw is made from hexagon bar and functions as a locking nut for the assembly, while the V-belt fan pulley is of interesting construction, being two light pressings cast in a flanged aluminium boss. At the rear end the crankshaft terminates in a robust flange bored out to take the clutch shaft spigot bearing. To this flange Image Captions: The Frazer Nash-B.M.W. chassis. The suspension and anchorage of the front wheels. | ||