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).
Outlining recommended settings for shock dampers and springs on 20/25 HP and 40/50 HP models.
| Identifier | ExFiles\Box 16\5\ Scan046 | |
| Date | 16th December 1931 | |
| Copy. W/W W/Sevres. C. to Hs.{Lord Ernest Hives - Chair} By.{R.W. Bailey - Chief Engineer} Mx.{John H Maddocks - Chief Proving Officer} SP.{Mr Spinney} W/S. X7520. Hd{Mr Hayward/Mr Huddy}/SB.{Mr Bull/Mr Bannister}4/LS.16.12.31. X5520 Re: Shock Damper Loads. 20/25 HP and 40/50 HP. We have now had sufficient experience in regard to various loadings of our hydraulic shock dampers to be able to establish a number of settings which can be regarded as the most suitable for certain conditions, and with which we have been able to satisfy many difficult owners. For your information we set out below a few particulars of the best spring and shock damper combinations for the more prevalent complaints which are likely to be encountered and we also attach hereto a chart giving in tabulated form full information in regard to the loading and valve leak of the various dampers referred to. 1. 20 HP and 20/25 HP. Standard Springs. The most usual complaint is pitching and "kicking" at the rear, and additional damping all round is necessary. The rear springs should be of a strength to give a buffer clearance of from 3.250" to 3.750" under normal load, and they neednot be of the grooved type unless there is a complaint of 'poor low speed riding', although better all round results are obtained with lubricated springs. The best shock damper setting is that marked CP-20 and CR{Mr Cra???ster / Mr Chichester}-20 in the chart, and under these conditions the springing should be as good as it is possible to get without recourse to low ratings springs, and should satisfy 90% of our customers. If the car is known to do a lot of town work it may be advisable to increase the leak area to .00119 sq.in. (one .039 dia hole) but this leak should not be exceeded. Cont'd.{John DeLooze - Company Secretary} | ||