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).
Arguing against higher geared rear axle ratios to improve low-speed performance and acceleration, particularly for the Australian market.
| Identifier | ExFiles\Box 69\4\ scan0352 | |
| Date | 11th October 1927 | |
| Shr. London. C. to Hn.{F. C. Honeyman - Retail orders} Derby By HS.{Lord Ernest Hives - Chair} Hs.{Lord Ernest Hives - Chair} C. to C. London. +8771 RECEIVED Pt.C/S.G./M-11/10/27. Further to my memo. Pt.7/M-31-8-27 suggesting that we should endeavour to improve the power of our engines, I now beg to inform you I have several times recently had my attention drawn by owners of those who drive both S.G. and P. models, to what they call the sluggishness of the latter. They point out that many of the old S.G. models are quicker in the get-away and acceleration than the N.P. and in this I am compelled regretfully to agree with them. Part of this may be due to the fact that the S.G. in question have 14/52 rear axle ratio while the P. are fitted with 15/52 rear axle. I have already expressed my belief that nothing higher geared than 14/52 is suitable for Australian conditions and I was astonished when the first P. arrived fitted with a ratio of 15/52. Upon expressing my disapproval I was informed that the greater power of the P. engine warranted the fitting of higher geared axle, and though I agree that this may be so under English or European conditions I cannot agree that it applies to Australian conditions for several reasons. Firstly, although the P. may develop more power at practically all speeds than did the S.G. yet at low speeds around maximum torque speed I fancy the advantage will be found to be on the side of the S.G; at all events that is the impression one gets when driving. It should be remembered that out here the roads are so bad that the maximum speed on either type is never, or seldom, obtained, while to put up a reasonably decent showing against the better class American cars it is absolutely essential we should have as quick acceleration and get-away combined with good hill climbing at low engine speeds on top gear. To sum up, I think we are unnecessarily handicapping our new model by increasing the rear axle ratio above that considered desirable in the past with the S.G. and I hope you will be able to persuade those responsible that my contention justifies them in reverting to 14/52 for all chassis intended for this market. Pt. Per F.{Mr Friese} Mc. P.S. On reading the above I find same is somewhat ambiguous. What I really want to convey is that though the torque exerted by the N.P. should be much greater at its maximum torque speed than is | ||