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).
Table of ratios and speeds for a 40/50 HP chassis with a four-speed gearbox.
| Identifier | ExFiles\Box 4\8\ 08-page12 | |
| Date | 4th June 1926 guessed | |
| X.469 22. X.3426. RATIOS & SPEEDS OF 40/50 HP. CHASSIS WITH X.469. FOUR SPEED GEAR BOX. Axle. Gear. Fourth Direct. Third Second First Reverse. 16 x 52 3.25 4.83 7.22 11.07 11.07 17 x 52 3.06 4.54 6.79 10.42 10.42 18 x 52 2.89 4.29 6.42 9.84 9.84 SPEEDS IN M.P.H. AT 1000 REVS. OF ENG: 895 mm WHEELS. Axle. Gear. Fourth Direct. Third Second First Reverse. 16 x 52 29.85 20.08 13.43 8.76 8.76 17 x 52 31.71 21.35 14.26 9.31 9.31 18 x 52 33.56 22.58 15.09 9.86 9.86 SPEEDS IN M.P.H. AT 1000 REVS: OF ENG: 935 mm WHEELS. Axle. Gear. Fourth Direct. Third Second First Reverse 16. x 52 31.16 20.97 14.03 9.15 9.15 17 x 52 33.10 22.22 14.89 9.72 9.72 18 x 52 35.04 23.53 15.77 10.29 10.29 SPEEDS IN M.P.H. AT 1000 REVS. ON ENG: 905 mm x 150 WHEELS. Axle. Gear. Fourth Direct. Third Second First Reverse. 16 x 52 30.83 20.74 13.87 9.05 9.05 17 x 52 32.75 22.05 14.73 9.62 9.62 18 x 52 34.69 23.33 15.58 10.20 10.20 | ||