SOUNDPROOFING In any car, a certain amount of noise is transmitted to the passenger compartment and, if of a high enough level, can not only be annoying, but also tiring on long journeys. Therefore, the elimination or reduction of this noise is desirable for more enjoyable and safer motoring.
The passengers in a car can be subjected to noise from various sources: the wind rushing round the body and blowing round badly sealed doors; mechanical noise from the engine and transmission; the exhaust; tyres drumming on the road; and noise cause by the vibration of the car's sheet metal panels. By insulating the body of the car, it is possible to eliminate or considerably reduce a large Proportion of this noise. Sound Service (Oxford) Ltd., of Witney, Oxon, are leading manufacturers of sound proofing materials, and their Autosound kit for the Mini contains a variety of these, each designed specially to reduce or eliminate the various types of noise experienced in the car. The following is based on information supplied by the company.

Before doing anything, the front seats should ideally be removed as well as all the carpets and floor mats. Then the floor should be thoroughly cleaned. Leave in place trim carpet below parcel shelf and on wheel arches.
With the floor/bulkhead area clear, check for any holes and seal them with the mastic sealing strip supplied in the Autosound kit. This should also be applied to all rubber grommets where cables and pipes pass through the bulkhead and to the area at the bottom of the steering column. The object is to obtain an air-tight seal between the engine and passenger compartments.
Ali the components of the kit are pre-cut to shape and numbered, and the next step should be to lay them out and identify them. Two rigid bitumen and four pliable damper pads are included and these should be stuck in each footwell and in other areas of the floor where vibration is apparent. These can be found by gently tapping with a rubber hammer; if they emit a thumping sound, they should be treated. Each damper pad is selfadhesive on one side, allowing it to be stuck in place and it acts as a stiffener. As the panel vibrates, the board is alternately stretched and compressed and thus acts to slow down the vibration reducing the noise level.
The next job is to fit pre-cut pieces of Sound Barrier Mat to both sides of the bulkhead. These are made from a grey foam material with a stiff rubber-like facing on one side. The material is glued in place on the panels, using the adhesive supplied in the kit, the foam being placed against the steel panel. In practice, this allows the sound waves to pass through the panel, into the foam where some of the energy of the vibrating air particles is dissipated as they pass through its tiny passages, and then bounce back from the stiff outer layer. In this way much of the sound is trapped between the two layers and gradually losses its energy as it bounces to and fro.
For the under-bonnet area, the Autosound kit includes some items in Neoprene faced felt. These are glued in place in the same manner as the Sound Barrier Mat, the smooth surface outermost. Like the foam material, the felt has tiny passages between its fibres that help dissipate energy of the vibrating air particles. This material cuts down multiple reflections of sounds within the engine compartment, preventing the build up of noise.
One further item provided is a roll of Weatherseal tape for sealing doors, etc. Rather than placing this along the entire opening, it is often more effective simply to place it where the air is actually leaking through the seal, and to find this is a simple matter. It is necessary to drive the car with a passenger who should have a section of normal garden hose. By holding one end of the hose to his ear and the other to the door seal, he can determine exactly where the seal is deficient. By marking the extremities of the leak with chalk or some similar means, it is a simple matter to cut the Weatherseal tape to size and install it exactly where needed.
The final job is to replace the carpets and seats and check the operation of all instruments and lights, etc., in case any wires have been displaced during the operation.