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 for the Wraith model's suspension springs and dampers.
| Identifier | ExFiles\Box 9\5\ 05-page216 | |
| Date | 20th June 1938 | |
| 646 To By.{R.W. Bailey - Chief Engineer} c. to By/HEB.{H. Biraben} c. to Roy{Sir Henry Royce}/Les.{Ivan A. Leslie} Rm{William Robotham - Chief Engineer}/AFM.{Anthony F. Martindale}9/JH.20.6.38. WRAITH SUSPENSION DETAILS. SPRINGS. We find we can do with lighter springs on the rear of Wraith than those previously called so, so attached is a new chart giving spring poundage necessary for given body weights. This will enable 1150 lb. springs to be used. Will you please instruct accordingly. It should be remembered that we only order springs with 50 lbs. variation, and the nearest spring to the theoretical poundage be used, and this may be either stronger or weaker. DAMPERS. The rear shock dampers should have an initial load of 40 lbs. on the ball, and a 2 second leak in both direction, as measured on our experimental test machine. On this machine a 10 lb. weight is fixed on the end of a 2' 0" lever, and this rotates the damper arm. An electric time clock measures to 1/10 second the time taken for the damper arm to rotate 22 1/2° under this couple. It is usually found that a hole .046" dia. in the valve stem gives the correct result. The front dampers should also have a 40 lb. load, but a 3 second leak in each direction. Rm{William Robotham - Chief Engineer}/AFM.{Anthony F. Martindale} | ||