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).
Analysis of an unbearable booming noise in a 25 HP car, focusing on body and chassis issues.
| Identifier | ExFiles\Box 137\4\ scan0312 | |
| Date | 10th April 1931 | |
| To PN.{Mr Northey} From Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} C.to Sg.{Arthur F. Sidgreaves - MD} Wor.{Arthur Wormald - General Works Manager} c. to Da.{Bernard Day - Chassis Design} E.{Mr Elliott - Chief Engineer} γ 634 Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer}8/MJ.10.4.31. GNS-2. X.634. X.7960. This 25 HP. car was sent up to us to deal with booms. We consider that the body on this car is worth the attention of Ev.{Ivan Evernden - coachwork} or some other expert, and could with advantage be tried by everybody connected with the improvement of coachwork. The reason we say this is because when the car is allowed to coast at from 30 to 35 m.p.h. over tram sets there is an almost unbearable boom in the rear seats. We think this is such a bad feature that it is just as important to ask the coachbuilders who are producing this type of body in quantities for R.R. to find out the cause and eliminate it as it is for us chassis makers to deal with the booms brought up from the engine. As a matter of fact we are surprised that this boom had not been dealt with, or at least commented on, before the car was sent to Derby because if small obstructions could make a noise like this through the tyres it is clear the body is fundamentally susceptible to booms. In this particular car we should say that the booms in the front and rear seats due to the vibrations from the engine are now only present to a subdued extent, which, considering the body characteristics previously mentioned, is as much as we can reasonably expect. 18-G4. which has recently been in London is our best answer to the booming of the 25 HP. but it is hardly an economical proposition to fit the Diamond engine mounting to the existing chassis. We want to emphasize that bodies such as that fitted to GNS-2 are likely to boom intolerably over any periodically interrupted road surface when coasting in neutral with the engine stopped. We should not like this boom to be confused with the one with which we have struggled as chassis complaints. We are so concerned about this body that we are bringing the car down with us on Wednesday next to demonstrate its imperfections and we should like Mr. Grylls to stay with the car and inconjunction with Mr. Honeyman and Ev.{Ivan Evernden - coachwork} to do what he can to assist the coachbuilders to get it right. Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} | ||