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).
Comparison table of steering system specifications for various models and configurations.
| Identifier | ExFiles\Box 95\1\ scan0245 | |
| Date | 5th December 1935 guessed | |
| COPY. | | SpectreCodename for Phantom III. | SpectreCodename for Phantom III revised. | La{L. A. Archer} Salle. | 20/25 with SpectreCodename for Phantom III box. | 20/25 with revised Spec. box. | 20/25 suggested. | 20/25 with Marles L.7. | 20/25 R.R. Steering. | Phantom R.R. Steering. | |---|---|---|---|---|---|---|---|---|---| | Helix angle. | 6°35' | 5°48' | 7°30' | 6°35' | 5°48' | 5°48' | 8°37' | 8°27' | 7°15' | | Lead. | .800 | .700 | .600 | .800 | .700 | .700 | .665 | .700 | .720 | | Column ratio. | 15.32 | 17.5 | 18.75 | 15.32 | 17.5 | 17.5 | 21.3 | 12.55 | 13.10 | | Lever ratio. | 1.062 | 1.062 | .825 | .997 | .997 | .872 | .810 | .997 | 1.135 | | Overall ratio. | 16.3 | 18.6 | 15.5 | 15.27 | 17.4 | 15.85 | 17.2 | 12.5 | 14.85 | | Turns of wheel. | 3.25 | 3.7 | 3.1 | 2.75 | 3.25 | 2.75 | 3.1 | 2.25 | 3.0 | | Pendulum Lever. | 7.00 | 7.00 | 9.00 | 8.25 | 8.25 | 9.437 | 10.15 | 8.25 | 7.75 | | Pendulum Lever Angles. | 77° | 77° | - | 65° | 65° | - | 52°45' | 65° | 71° | | ||