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).
Modifications and tests performed on the car's suspension damping system.
| Identifier | ExFiles\Box 18\3\ Scan186 | |
| Date | 11th November 1930 guessed | |
| -2- The car was improved very considerably by these modifications; but it was immediately noticed that the rear springing was too effectively damped (no Hartford friction damping was applied). The rear dampers were then modified by drilling .032" dia. holes in the H.P. valves. Very little difference was appreciated, and further damping on the rear (applied on the Hartfords) made the rear definitely harder. Pitching was only slight, and was definitely improved by applying 15 lbs. friction damping to the front of the car. With this combination of front springing and damping the results were encouragingly good; the front riding was very soft (drilled valves) at low speeds and there was sufficient damping to eliminate rear seat pitching. The next test carried out was with no damping at all on the rear, the front being unaltered. The rear seat riding was very good except for very slow bouncing of large amplitude at speeds over 35 m.p.h. Damping was then applied to the rear (by Hartford) until these movements were damped out, 50 lbs load was required to do this without appreciably making the low speed riding harsher. The rear hydraulic dampers were then set at 60/60 lbs and connected up, the Hartfords were slacked off altogether. This combination gave very good riding | ||