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).
Addition of sound insulation to the 4¼ Litre Bentley chassis.
| Identifier | ExFiles\Box 138\1\ scan0240 | |
| Date | 18th March 1936 | |
| Hs{Lord Ernest Hives - Chair}/FD.{Frank Dodd - Bodies}3/KW.18.3.36. Sound Insulation on 4¼ Litre Bentley. We have fitted up the first of the production 4¼ litre Bentley chassis with dashboard insulation, scuttle insulation, and new felt mats to the floorboards and foot wells. The resultant quietness from engine noises, tappets etc. was, as heretofore, most marked, and we recommend that this scheme be carried out on all production Bentley cars. The scheme as tried consists of 3 layers of ¼" felt covered with black fibre on the dashboard (this will be reduced to 1" in thickness under compression, and is held in position by split pins and washers. Felt ½" thick to all the scuttle panels, and felt mats underneath the pile carpets ½" thick, replacing the sorbo type of mat. The total extra weight of material added amounts to 16 lbs. 8 ozs., from which we delete sorbo mats - 8 lbs. 0 ozs. 8 lbs. 8 ozs. extra weight. It will be seen from these figures that the extra weight is not excessive and the results certainly justify the additional expense. We are experimenting at the moment with Seapak covered with carpet for the dashboard, with the idea of the makers supplying the material cut to pattern. The weight of the latter would be exactly the same as felt. As production will be requiring a scheme to carry on with at once, we would suggest that felt is used until such time as our tests are completed. Alterations will be necessary to the dashboard, oil union and the petrol tap. These will require lengthening. Provision should also be made for the petrol reserve and main dashboard plate to be fitted on the fibre. | ||