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 road spring specifications for two Phantom II vehicles.
| Identifier | ExFiles\Box 17\1\ Scan029 | |
| Date | 12th May 1931 | |
| Y7410 12.5.31. X4663. RE. PHANTOM II. ROAD SPRINGS ON BUMPER. Serial No. | K.460 | K.470 Piece No. | F.83317 | F.83317 Loaded Camber. | Flat. | Flat Loaded lbs. | 1165 lbs. | 1158 lbs. Initial Camber. | 4.500 | 4.500 Thickness of main plate. | .254 | .256 2nd plate. | .248 | .248 3rd plate. | .242 | .240 4th plate. | .240 | .239 5th plate. | .240 | .240 6th plate. | .240 | .239 7th plate. | .228 | .228 8th plate. | .230 | .232 9th plate. | .231 | .231 | ||