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).
Page discussing the effects of axle ratios on speed, fuel consumption, and engine temperature.
| Identifier | ExFiles\Box 66\4\ scan0331 | |
| Date | 11th November 1925 | |
| R.R. 493a (50 H) (D.D. 31, 12-6-25) J.H.D. EXPERIMENTAL REPORT -2- Expl. No. REF: HJS/LCS/11.11.25. with a 14-tooth axle it is doubtful whether a maximum speed in excess of 70 m.p.h. will be obtained. With regard to petrol consumption, it is anti- cipated that the lower geared axle will increase the fuel consumed per mile by from 5 to 7½% with normal driving: One point which should not be missed in connection with axle ratio is that with a lower top gear the tendency to over-heat is increased somewhat. This is because the car speed through the air is diminished for max. power at any fixed engine r.p.m. The type of person who requires a low geared axle will obviously hang on to top as long as possible. HJS | ||