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).
The specifications of a single plate long clutch, with comparisons to those used in Lincoln & Packard vehicles.
| Identifier | ExFiles\Box 173\2\ img062 | |
| Date | 13th February 1934 | |
| V SGW OR E By Da{Bernard Day - Chassis Design} HDY{William Hardy} H$/Rm{William Robotham - Chief Engineer} EV{Ivan Evernden - coachwork} Hs.{Lord Ernest Hives - Chair} Feb. 13th /34 Long Clutch. I send you a drawing of the single plate long clutch as fitted to the Lincoln & Pacard. The Lincoln dimensions are slightly smaller and are given in pencil. The over all ratio as used on the Pacard is 61.38. They get the o/o separation with about 4.25 clutch pedal travel, .65 being spring. They fit needle bearings in their cross shafts. With clutch springs of 1850 they have only a pedal pressure of 30 lbs they allege which seems improbable as it is 100% efficiency. If you can make use of this clutch on the SpectreCodename for Phantom III or would like one to refer to will purchase on receipt of Cable. Clutch driven member weighs 7.5 LBS. Cover plate assembly 35 LBS. Max torque for which designed 325 LBS ft- Max out of truth running of centre plate .015- | ||