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).
Configuration of two S.S. chassis for testing engine noise and roughness.
| Identifier | ExFiles\Box 14\6\ Scan083 | |
| Date | 20th June 1929 | |
| To Hs{Lord Ernest Hives - Chair}/AJL. from Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} X7230 Hs{Lord Ernest Hives - Chair}/Rm{William Robotham - Chief Engineer}3/LG20.6.29. ENGINE NOISE AND ROUGHNESS. X7770 The position of the three S.S. chassis at present is : 19-EX. A standard S.S. car with the exception that the exhaust down pipes is arranged so that it can easily be altered in shape at the lower end. The engine feet also have thicker rubber on the frame side of the engine foot and thinner on the outside, but we have proved that this makes little difference to the main complaint. [Diagram showing a cross-section of a rubber mounting with dimensions .250 and .062] It may be that with less compression on the rubber we may get better results. We recommend that this car is used for getting the best compromise out of the engine mounting and exhaust system which we are at present using. 20-EX. Has diabolo engine mounting. We recommend that this car is used for reproducing 14-EX conditions as far as possible. There will then only be the S.S. unit (i.e. 3 ex. outlets instead of 4) to account for any difference between the two cars. We therefore think 20-EX should be fitted up with the Silver Ghost front and rear expansion box (this has previously been fitted to this car) and contd :- | ||