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).
Comparing independent front suspension systems, detailing issues with oscillations, steering reactions, and cornering performance.
| Identifier | ExFiles\Box 154\1\ scan0287 | |
| Date | 18th August 1936 guessed | |
| the most violent front end oscillations were set up resulting in powerful steering reactions, and a most violent sideway vibration of the steering column. This last mentioned feature which was more intense than we have ever seen before was probably accentuated by the presence of the stiffening tube fixed to the side channel carrying the steering box. We should certainly not recommend a compromise which was so dependent on the fitting of the stabiliser bumper. From our experience with the independent front suspension which we designed and tried on the P.II chassis, the Gordon Armstrong behaves very largely in all respects as we should anticipate, but we were not aware that the result could be made to perform to the standard achieved by using a stabiliser bumper. Dealing with the principle of the suspension, this has certain disadvantages which may be enumerated as follows:- (1) Low rolling centre which, however, is not very serious on a car with a low centre of gravity like the Bentley. (2) A geometrical error in the steering as compared with our P.III scheme. This does not appear to be sufficiently pronounced to bring up steering reactions. (3) Under-steering due to leaning of the wheels going round the corners, and the alteration of the point of contact with the road. Hs {Lord Ernest Hives - Chair} /Rm {William Robotham - Chief Engineer} found the steering on corners at 70 m.p.h. a great effort and yet it would only just self-centre at 20 m.p.h. This may be improved by reducing the castor angle from 4 to 1 degree, and altering the kingpin angle laterally to restore self-centering. The leaning effect of the wheels however would remain. Armstrong is going to carry out these alterations to see what improvements result. Our general conclusions on this matter are that the roll bar suspension on the design of which we are engaged at the moment for the Bentley is superior in all the points mentioned to the Gordon Armstrong, and possesses other advantages in addition such as less unsprung weight, possibly lighter overall weight, and greater lateral rigidity. We are | ||