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).
Specifications, weight, and rating of sports car rear springs compared to standard springs.
| Identifier | ExFiles\Box 67a\2\ scan0108 | |
| Date | 28th January 1928 | |
| X8410 To EY. from Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} c. to Da.{Bernard Day - Chassis Design} c. to WcP. Hs{Lord Ernest Hives - Chair}/Rm{William Robotham - Chief Engineer}1/LG28.1.28. SPORTS CAR REAR SPRINGS. X8410 X8774 We recommend that the following springs are ordered for the sports car :- Front 1000 lbs. to F.77917. Rear 1500 lbs. reduced camber 25% stiffer type. In the sports car rear springs that we have received the makers appear to have made no effort whatever to reduce the weight. We think that we ought to tell them clearly what weight we expect these springs to be. Our argument is as follows :- The rating of the 1500 lbs. sports spring is 310 lbs/1" or the same as the rating of a standard 1850 lbs. spring. The maximum to buffer deflection of a sports car spring is 10.1", of the standard is 12.125"; therefore since the sports spring has the same rating and 17% less deflection as the 1850 lbs. standard spring it should require 17% less material for the same equivalent maximum stress. Our 1850 standard spring weighs about 76 lbs. We think it could be made to weigh 70 lbs. only with safety as our 2300 lbs. std. springs only weigh 67 lbs. and they are perfectly satisfactory. Therefore we ought to get sports car springs 15% lighter than 70 lbs. or 60 lbs. weight. Actually the 1500 lbs. sports car springs with which we have been supplied weigh 82 lbs. The whole sports car body Contd :- | ||