Sound Proofing / Insulation: Description and Operation

Expanding Foam Acoustic Seals







Expanding foam seals numbers 1 to 10 are fitted to various sections of the body side panel, bodyside closing and bodyside inner panel. Seal numbers 11 and 12 are fitted inside the rear longitudinals.

Expanding foam acoustic seals are used in various closed sections of the body to improve vehicle refinement. The seals expand during the factory paint process, thus locking them into position. The seals are used in various locations throughout the vehicle.

The main function of the seals is to insulate the cabin from noise and vibrations, particularly road noise. They are located such that they prevent noise accentuation along a section and also reflect air borne noise away from the cabin.

A secondary function of the seals is that the internal sections are sealed from the infiltration of water, air, dust and gases.

Another advantage of the seals is that they marginally increase the overall stiffness of the body and its structural performance in case of a crash.

The seals are manufactured from an expandible synthetic rubber, 'Betacore 4300'.

All the seals are fitted in the body-in-white areas, and after going through the paint baking process expand up to eight times original size.

Replacing seals

As paint oven temperatures used in a repair workshop are significantly lower than those that are used during manufacture of the vehicle, a different process is required to replace the seals in service.

After a repair that involves replacement of a section containing expanded foam, the new section must be injected with an approved sound dampening foam. The sound dampening foam should be injected after paint refinishing and application of cavity wax. When injecting the foam, ensure the foam fills a complete cross section of the cavity.