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).
Comparative weights analysis of the 4¼-Litre Bentley Fully-Floating (K & M Series) and Semi-Floating Axles.
| Identifier | ExFiles\Box 88\3\ scan0260 | |
| Date | 10th August 1938 | |
| 258 wls 202 To By.{R.W. Bailey - Chief Engineer} from Rm{William Robotham - Chief Engineer}/Cr.{Mr Cra???ster / Mr Chichester} c. Da.{Bernard Day - Chassis Design} c. Hdy.{William Hardy} Comparative weights 4¼-Litre Bentley Fully Floating Axle (K & M Series), and Semi-Floating Axle. Semi-Floating Axle 148 lbs. 1½ ozs. Fully Floating Axle 'K' series 118 lbs. 1½ ozs. Fully Floating Axle 'M' series 124 lbs. 2 ozs. Increased Weight over 'K' series 30 lbs. 0 ozs. Increased Weight over 'M' series 24 lbs. 8½ ozs. The increase in weight on the semi-floating axle over the fully-floating axle can be accounted for as follows:- | | Semi-Float | Full-Float M | Difference. | | :--- | :---: | :---: | :---: | | | lbs. ozs. | lbs. ozs. | lbs. ozs. | | Axle Shafts (less flange on semi-float) | 26 11 | 20 0 | 6 11 | | Flanges (semi-float axle shafts) } | 6 0 | | | | Hubs Fully-float | | 13 1 | -7 1 | | Axle tubes and Spring Pads | 42 3 | 34 2 | 8 1 | | Centre casing | 11 7 | 9 2 | 2 5 | | Crown wheel | 8 1 | 6 13 | 1 11 | | Pinion | 4 8 | 2 13 | 1 11 | | Differential casing | 7 2½ | 6 1 | 1 1½ | | Pinion Brgs. | 2 0 | 1 4½ | 0 11½ | | Hub brgs. | 4 0 | 2 7 | 1 9 | | Other Brgs. | 3 0 | 1 14½ | 1 1½ | | Bearing Housing Axle Shafts | 3 0 | 2 10½ | 0 5½ | The Foregoing Differences Account For 21 0 'K' series axle is 5 lbs. 7½ ozs. lighter than 'M' series because the axle shafts weigh 15 lbs. 2 ozs. against 20 lbs. on 'M' series, and the wheel drivers are 9½ ozs. lighter. | ||