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).
List of specifications for insulating and lining various parts of a car's interior to reduce noise.
| Identifier | ExFiles\Box 138\1\ scan0137 | |
| Date | 14th March 1935 | |
| -2- (e) The remainder of all floorboards and surfaces should be lined with felt 1/4" thick, and in the case of sunken foot wells and heelboards, these should be lined with felt and have a protection of rubber sheeting against damp, and finally covered with matting. (f) The space underneath the rear seat should be filled in with a sheet metal shield made of 18 gauge steel, coated with felt 1/4" thick on the top side, and securely screwed down. A hinged lid{A. J. Lidsey} should be provided for access to the battery. (g) The luggage boot and metal base at the foot of the rear squab should be lined out with felt 1/4" thick, and covered with a layer of protecting material such as thin hide. (h) A leather jacket should be fitted over the change speed gate, this prevents any noise coming out of the gearbox via the gate. (i) The speedometer and rev. counter cables should be brought up on the engine side of the dashboard and suitably clipped, and taken through the dashboard via 2, 1/2" dia. holes opposite the respective instruments. Rubber bushes should be used to seal the holes in the dashboard. (j) All surplus holes in the dashboard must be plugged up, and all slots in floorboards originally cut out for cables must be filled up. (k) The oil pipe union F.54872 and the petrol tap valve spindle F.83635 must be made .550" longer, so as to clear the felt and fibre on the dashboard. We have experimented with removing various sections of the above Scheme, and have come to the conclusion that although the dash insulation is relatively the most effective item with regard to quietening the engine noises, the whole success of the scheme depends upon its entirety. The metal shield underneath the rear seat and the lining of the boot are most essential for keeping out "titter" and tail pipe noise. Hs{Lord Ernest Hives - Chair}/G.H. Whyman. | ||