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).
Blueprint graph showing spring poundage selection for 20 HP front and rear axles based on vehicle weight.
| Identifier | ExFiles\Box 106\1\ scan0141 | |
| Date | 23th August 1928 guessed | |
| 20 HP REAR SPRINGS REAR SPRING POUNDAGE 1110 1000 900 800 700 HEAVY LIGHT CAR SPRUNG FOR FOUR PASSENGERS ADD HALF LUGGAGE TO EACH SPRING REAR AXLE WT. CWT CAR EMPTY 16 17 18 19 20 21 20 HP FRONT SPRINGS 800 750 700 650 600 FRONT SPRING POUNDAGE CONTINENTAL NORMAL CAR SPRUNG FOR FOUR PASSENGERS UNAFFECTED BY LUGGAGE FRONT AXLE WT. CWTS. CAR EMPTY 12 13 14 15 16 | ||