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).
Investigation into vehicle booming and radiator movement, summarising findings and proposing future permanent solutions.
| Identifier | ExFiles\Box 28\5\ Scan055 | |
| Date | 2nd April 1931 | |
| (2) Hg/Rm.{William Robotham - Chief Engineer}7/KT.2.4.31.cont. pressures, these two features may accentuate the jellying produced by removing the rear feet. One of the Bales cars that we treated for booming, 129.GN, was as bad for radiator movement as any we have tried. We do not think that our cure has increased the radiator movement more than, if as much, as 10% on this car. A feature that has been commented on by Bales is that removing the rear engine feet has a beneficial effect on the amount of torque reaction felt in the front seats. Summarising this matter. (i) We do not want to under-estimate the existing complaints of radiator movement and road shocks. (ii) We agree that these are undesirable and that we are in danger of increasing both when we fit low rating front springs. (iii) We can see no reason, however, why we should be impossibly bad with the 3" deflection road springs when we remove the engine stiffness from the frame because P.I. had a three point engine mounting and was not impossibly bad. (iv) We agree that it would be advisable to try a test case over bad fast French roads to ascertain the value of the rear feet under the worst conditions we know of. There is no doubt that on a sports car the selectivity of the steering suffers when the engine stiffness cannot be utilised. (v) Having regard to all these facts, we believe that booms and torque reaction are so irritating to the passengers (who generally speaking own but do not drive 80% of our cars) that the benefit incurred by removing the rear feet will altogether out-weigh the accompanying disadvantages. For Continental touring cars, on the other hand, we consider that the present standard arrangement is essential for controllability. Admittedly we must try and improve the situation with the minimum of delay. (2) Future Measures for Permanent Solution. At the moment we have done so much work on booms with so little result that we despair of being able to use the rigidity of the 6 cyl. 40/50 engine to give good steering and prevent front end shake. The booming behaviour of bodies appears to be so capricious to make this possible. Our endeavours therefore are directed to making the frame sufficiently self supporting to overcome the trouble either (a) With diamond engine mounting. | ||