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).
Specification sheet for the thickness of leaves on 20 HP road springs.
| Identifier | ExFiles\Box 106\1\ scan0249 | |
| Date | 13th May 1931 | |
| 85410 FILES. 20 HP. ROAD SPRINGS. 13.5.31. Thickness of Leaves. Front initial camber 4.500" Normal Load 725 lbs. .5 neg. Rear " " 6.100" " " 1045 lbs Flat. LEAF. FRONT SPRING REAR SPRING. NUMBER. F.{Mr Friese} 56511 F.{Mr Friese} 57192 Edge A.{Mr Adams} Centre B. Edge A.{Mr Adams} Centre B. Main No.1 .217 .216 .262 .259 2 .200 .202 .261 .259 3 .188 .190 .266 .254 4 .188 .189 .250 .243 5 .181 .183 .245 .231 6 .170 .170 .242 .230 7 .166 .165 .235 .224 8 .169 .169 .234 .220 9 .168 .168 .235 .223 10 - - .235 .224 The front spring plates average .001" thicker in centre than at edges. | ||