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).
Chassis twisting, frame distortion, and high-speed wobble.
| Identifier | ExFiles\Box 29\1\ Scan027 | |
| Date | 12th June 1925 | |
| R.R. 493A (50 HD{Mr Hayward/Mr Huddy}) (D.D. 31. 12-6-25) J.H.D. EXPERIMENTAL REPORT -2- Expl. No. REF: HSL/LG5. 9.25. As far as we could see the whole chassis was twisting transversally about some point towards the rear of the frame. This impression was strengthened by the fact that the bonnet lifted on each side opening a gap of about half an inch every wobble, presumably due to frame distortion. The wobble, having attained a certain small amplitude did not build up but maintained the same characteristics to the max. speed of the car (65 m.p.h.) Where the road surface was good and bad in patches the wobble was apt to become worse on the bad patches. In no case was the amplitude anything like that which we experience with a bad high speed wobble. The steering of the car is remarkably high geared, and yet the wheel only oscillated through a small angle. We observed the car, while wobbling, from another car in front, the wheels did not leave the ground. We repeated the observations from the side of the road, we could not see the wheels leave the ground. We jacked up the car in the centre of the front tube underneath the radiator and found we could set up a torsional vibration in the frame but of a slower period than that of the high speed wobble we experienced. With the tyres in contact with the ground, however, we should expect the frequency to be increased. We showed the car to Mr. Healey before parting with it, he admitted we were obtaining a real high speed wobble. Further details of the car are :- contd :- | ||