This report describes the application of information, obtained from earlier investigations, to the reduction of road-excited body-noise in a small car of unitary construction. Fore-and-aft compliance was introduced into the front suspension by means of rubber-in-shear mountings in order to improve the transmission loss for vibrations in the fore-and-aft direction. This modified suspension produced the greatest improvement, achieving noise reductions of up to 10 dB in the region of 200 c/s. Further reductions of up to 5 dB were made by the use of an efficient panel damping treatment, together with a thick floor-covering material. The effect of this treatment was more marked with braced-tread tyres fitted to the car than with conventional tyres. Although the level of road-noise below 80 c/s associated with braced-tread tyres was reduced in the fully modified car to the level associated with conventional tyres on the original vehicle, slightly better overall results were obtained using conventional tyres. The reduction of low frequency noise when conventional tyres were fitted outweighed the smaller reductions obtained in the frequency range 125-200 c/s when braced-tread tyres were used with the fully modified vehicle. The level of road-noise in the test car in its final form is comparable with the quietest of a sample of 52 cars tested at M.I.R.A. Attempts to reduce the road-noise further by modifications to the rear suspension have not been successful. (Author)

  • Corporate Authors:

    Motor Industry Research Association

    Lindley Near Nuneaton
    Warwickshire,   England 
  • Authors:
    • Dixon, J C
    • West, J
  • Publication Date: 1965

Media Info

  • Features: Figures; References; Tables;
  • Pagination: 14 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00261310
  • Record Type: Publication
  • Report/Paper Numbers: MIRA 1965/3
  • Files: TRIS
  • Created Date: Oct 22 1974 12:00AM