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).
With a diagram discussing the dimensions and performance of springs and rubber buffers for specific car models.
| Identifier | ExFiles\Box 72\3\ scan0192 | |
| Date | 28th October 1924 | |
| x9410 Expl: Dept: Messrs. Rolls-Royce Ltd., Derby, Angleterre. 28th. Oct. 1924. x9941 x9410 Hotel de France, Chateauroux, Indre, France. Mr. Lidsey from Hs.{Lord Ernest Hives - Chair} RE. 98-NK CAR. The springs fitted to this car are the 12½% stiffer. The rubber buffers should be to the following dimensions, and gave a spring clearance of 1.300". [Diagram of a rubber buffer with dimensions 2 3/8" and 2 1/4"] You might check the buffers to see that they are to these dimensions, if not, let us know. The springs you have been running on 9-PK car are the 20% stiffer. It is possible that we might wire you to fit the spare Woodhead springs, which were carried on 98-NK car, on to that car because our tests on the bumping rig are shewing the Firths springs to be less reliable and it would therefore appear that we shall continu contd:- | ||