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).
Phantom III tyre noise issues, comparing different solutions and test vehicles.
| Identifier | ExFiles\Box 157\1\ scan0312 | |
| Date | 9th April 1936 | |
| x+332 PROOF. Phantom III Tyre Noise. Sg.{Arthur F. Sidgreaves - MD}16/E.8.4.36. Sg.{Arthur F. Sidgreaves - MD}7/E.9.4.36. The two types of tyre noise with which we have been dealing are - (1) Tyre noise on normal roads, groans below 30 m.p.h. (2) Tyre noise on setts. The palliatives for the two complaints are - (1) Rubber body mounting or rubber shackles about equally effective. 33-EX with the old type Dunlop '90' tyre was demonstrated by Rm.{William Robotham - Chief Engineer} to Cx.{Major Len W. Cox - Advertising Manager} as being equal to Ph.II. Tyre tread controlling feature. (2) Rubber shackles 50% improvement. Noise almost entirely independent of the pattern on the tyre. Rubber between axle and spring 10% improvement in one case, rather more in others. Rightly or wrongly, we understood that, in order to enable us to get vital parts of the car tested rapidly (these parts having been completely altered since the last 15,000 miles test) Sales would accept the noise on setts provided the tyre noise on normal roads was reduced. We certainly convinced ourselves and Cx.{Major Len W. Cox - Advertising Manager} that the rubber body mounting and original pattern Dunlop '90' tyre brought 33-EX up to Ph.II standard on normal roads. The car prepared for 15,000 miles therefore had rubber body mounting but no rubber shackles. Since then we have had 36-EX on the road. This has demonstrated one of the problems we are continually up against, the difference between one car and another. It is worse than 33-EX for tyre noise. It was only just completed at the last Conference and possibly justifies the policy of fitting rubber shackles to the 15,000 miles car, but there was no way of knowing that it would be worse until the car had been built. | ||