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 different brake drum types showing maximum temperatures and weight impact on a 4 1/2 litre Bentley.
| Identifier | ExFiles\Box 88\3\ scan0196 | |
| Date | 24th April 1936 guessed | |
| X258 Drum Max. Temp. attainable on 4 1/2 litre Bentley. Weight Increase of car. Standard 12" Bentley. 350ºC. 0 Aluminium 200ºC. - 8 lbs. 14" Bentley. 305ºC. + 26 lbs. 12" Bentley with helical ribs. 200ºC. Increase of 2 rear drums + 7 lbs. | ||