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).
Rear axle specifications and suggestions for various car models.
| Identifier | ExFiles\Box 114\1\ scan0159 | |
| Date | 7th October 1938 | |
| 1015 To By.{R.W. Bailey - Chief Engineer} from Rm{William Robotham - Chief Engineer}/Gry.{Shadwell Grylls} c. HS.{Lord Ernest Hives - Chair} c. Da.{Bernard Day - Chassis Design} c. Da{Bernard Day - Chassis Design}/Hdy.{William Hardy} c. Da{Bernard Day - Chassis Design}/EV.{Ivan Evernden - coachwork} Rm{William Robotham - Chief Engineer}/Gry.{Shadwell Grylls}1/MH.{M. Huckerby}7.10.38. REAR AXLES - ALL CARS. file 202 It is obvious from Da{Bernard Day - Chassis Design}/HB.{C. E. Harcombe}1/R.4.10.38 and the subsequent additions that although an 8 1/2" crown wheel might be suitable at .650 offset for the 6-cylinder Wraith lowest ratio of 4.0; neither with .650 offset nor 1 1/2" could it possibly function for the 8-cylinder engine. The eight-cylinder engine, giving a torque of 3200 lbs.ins., needs another axle. A revision of our ideas for the rationalised programme is required. We make the following suggestion; A B.III customer paying £1100 for his chassis deserves and can be given the best and lightest axle we can make. Let him have the .650 offset 8 1/2" crown wheel, at first fully floating and subsequently semi floating. For the other cars B.50, Wr.60, Wr.80, and P.IV we recommend 8 1/2" gears for those cars on which it will work - it still is open to experiment whether a 10/46 ratio 8 1/2" combination will function on Wraith - and for those cars on which the torque is too high we suggest 10" .850 offset P.3 gears. These need no development expenditure and will be adequate for any size of engine we shall use. No one can immediately say they are too robust for the 8-cylinder whether 5 1/2-litres or bigger, as we now 'swallow' their weight on Wraith. We have obtained samples of the axle gears used by Buick on their 'Century' and '90' type chassis. Both chassis have a 320 cu.in. engine. The former being a light car (3785 lbs. shipping weight) uses a 9 1/2" crown wheel of 10/39 ratio and 1.75 offset. The '90' is a heavy car (4585 lbs. shipping weight) and has a 10" crown wheel 9/41 ratio 1.75 offset. Both pinions appear to be about 40° spiral angle. The sizes of gears used by Buicks are in line with our suggestions in the preceeding paragraph. | ||