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).
Comparison of body rigidity and suspension between Spectre and Cadillac cars, discussing potential tests and improvements.
| Identifier | ExFiles\Box 92\1\ scan0121 | |
| Date | 5th May 1935 | |
| +304 To EG. c. to WDF. c. to R.{Sir Henry Royce} c. to Do. c. to Hy.{Tom Haldenby - Plant Engineer} c. to EV.{Ivan Evernden - coachwork} Rigidity of SpectreCodename for Phantom III Bodies. There is no doubt that on the two SpectreCodename for Phantom III cars we are at present running, neither the passengers nor the driver get the feeling of solidity experienced in the Cadillac car. We have been endeavouring to determine what is the cause of this. We have measured the stiffness of the Cadillac road springs. On SpectreCodename for Phantom III cars we have more flexibility than the Cadillac, in the soft position of the shock absorbers - which is the condition under which we always judge cars - we have no more loading than the Cadillac. The SpectreCodename for Phantom III frame is as stiff as that of the Cadillac, as is shown by the attached tests. Cadillac As pointed out by Gry.{Shadwell Grylls}, however, the complete car is more than three times as stiff as the complete SpectreCodename for Phantom III car, and therefore the SpectreCodename for Phantom III bodies so far built have nothing like the rigidity of that of the Cadillac. While it is improbable that we shall ever tolerate a body as heavy as that of the Cadillac, we think the suggestion that we should reproduce their conditions on one SpectreCodename for Phantom III car is a good one. We feel convinced that lack of body rigidity accentuates such troubles as axle dither, and creates a feeling of poor suspension. Since the complete car is 24 times as stiff as the best bare frame we know how to make, coachwork is the controlling factor. We are making some tests to see how much increase in rigidity we get by eliminating the sunshine roof. After the test in France, Park Wards were so enthusiastic about the results obtained on the Cadillac, that they were anxious to be allowed to build a body for a stiff chassis directly following the Cadillac body construction practice, and intimated that they would agree to paying half the cost of such a body. In the light of our present knowledge, we believe that such an experiment would be of great value. | ||