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).
Experiments to reduce car noise by mounting the body on rubber to isolate it from the frame.
| Identifier | ExFiles\Box 157\1\ scan0271 | |
| Date | 6th January 1936 | |
| -2- With regard to noise created when running a car over setts, this presents rather a different problem, because perfectly smooth tyres are just as bad as heavy tread tyres, and we feel that body acoustics will have a big bearing on the matter. As an example, filling the luggage boot on 33-EX car with waste gives us an improvement. The Cadillac has a period on setts which is little or no better than the worst periods on our cars. We therefore decided to mount the body on rubber, leaving the scuttle mounting solid. We first tried the car on the road with the body simply sitting on 4 blocks of rubber only, and not bolted down, and the result being satisfactory we fitted rubber slabs to all the body brackets and bolted the body down on to the rubber, isolating the bolts of course from the frame. We also disconnected the transverse stays at the back of the body, and thus obtained a body completely isolated from the frame except at the dashboard. This condition gave us a definite improvement for body noises generally, and particularly over setts. The rubbers we used were made by ourselves from a slab of rubber which we had in stock 1.375" thick with a durometer hardness of 70. The rubbers were made to the dimensions of the identical packing pieces removed, except that we made them .050" thicker to allow for compression by body weight and tightening up of the bolts. We found by measurement that a piece of this rubber 5" x 2" x 1" compressed .035" under a 100 lbs. load. No metal shims were used at all and the rubber packing thicknesses varied from .700" to 1.150". The rubber packings supplied by Hs{Lord Ernest Hives - Chair}/Les.{Ivan A. Leslie} to Bv. for fitting to 34-EX car have a durometer hardness of 35. Re/G.H. Whyman. | ||