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).
Technical memo discussing tyre noise and the methods used by various car manufacturers to reduce it.
| Identifier | ExFiles\Box 173\4\ img225 | |
| Date | 5th December 1935 | |
| COPY (Memo. from U.S.) DETROIT. To E.{Mr Elliott - Chief Engineer} from U.S. 5.12.35 Tyre Noise. It seems certain that the body mounting has a considerable amount to do with tyre noise at anyrate inside the car. Cadillacs, who mount their body on rubber fabric shims, very stiff, and insulate it from the road by rubber bushes in the rear springs and rubber between the rear springs and the axle, get most of their tyre noise from the front tyres, where there is no rubber insulation. Packards also use the hard rubber fabric shims under the body (said to be made of disused tyre fabric), and also use the rubber bush in the front of the rear spring (though not in the rear shackle). In the 120 the whole of the front suspension is mounted on rubber bushes, including the spherical joint of the torque taking member. They say that unless they use these rubber insulators, they get very objectionable tyre noise. They do still get tyre noise sometimes and this they think can be controlled by the tyres themselves. The big Lincoln body is mounted on the hard rubber fabric shims, and the springs have rubber bushes front and rear, but no rubber between the springs and the axles. The Lincoln Zephyr, because of its construction, is very sensitive to tyre noise and rubber bushes are used in both front and rear springs. Even the shock dampers are mounted on rubber. They also go to considerable trouble to deaden and absorb noise in the floor, roof and side panels. The Zephyr which we tried had a very bad axle, but the actual tyre noise as far as we could be judged, was not bad. All these firms, when they have done all this still get tyre noise sometimes and are constantly pressing the tyre makers for more silent tyres. The tyre makers appear to be offering various forms of plain circular ribs, some with as many as 10 ribs across the face of the tyre, but whether they give adequate traction, or are sufficiently non-skid, straight ahead, we have not had an opportunity of judging yet. (Olley says the rubber and fabric shims do not affect the body stiffness). Firestones and Goodyears both have specially silent treads which they say we can get in England. The 10 ribbed one is the General Tyre Co. and may not be obtainable there. I have telegraphed the information as to the shims in case it may be immediately useful. | ||