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).
High-speed wobble testing with different tyre setups and dampers.
| Identifier | WestWitteringFiles\P\2July1926-September1926\ Scan067 | |
| Date | 20th August 1926 guessed | |
| contd :- -2- should have expected the period to extend to 50 m.p.h. with the standard axle. It should be clearly understood that the car was not wobbling in the true sense of the word but only trying to wobble. It could be driven indefinitely at the critical speed without any danger or serious loss of control, but naturally the periodic movement of the steering wheel was highly objectionable. Upon uncoupling the dampers with these tyres, a genuine high speed wobble developed and it was impossible to drive the car above 55 m.p.h. Unfortunately the 6" Dunlop well base tyre is unobtainable in France, and so we were unable to determine whether the behaviour of this particular set was abnormal. With 6.2" Michelins, a slightly larger tyre, there were no signs of wobbles with the dampers coupled up. With 6.75" Dunlop well base balloons, the steering behaviour was even better than with the Michelins. We have therefore, the somewhat peculiar fact that the bigger section tyres are less prone to high speed wobble than the smaller section tyres. We have not been able to establish this in England, but naturally continental testing conditions are incomparably better for comparisons than those obtained in Britain. With high pressure tyres there are naturally no signs of high speed wobbles. contd :- | ||