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).
Report comparing the performance of two vehicles, SS. 20-EX and Phantom 8-EX, regarding tyre pressure effects, engine vibration, and steering wobble.
| Identifier | WestWitteringFiles\T\2January1929-June1929\ Scan022 | |
| Date | 1st January 1929 guessed | |
| contd :- -2- 70 m.p.h. in the district. When we dropped the tyre pressures to 25 lbs/sq.in. the relative merits of the two cars were entirely reversed. The SS.{S. Smith} 20-EX was little changed. The movement of the front end between 60 and 70 m.p.h. was a trifle more pronounced and the steering wheel became somewhat restless but the change was of a minor nature. The Phantom 8-EX on the other hand burst into a high speed wobble at 65 m.p.h. when the front end movement became most violent and the shocks on the steering wheel severe. (2) ENGINE VIBRATIONS AS FELT IN THE CAR. The Phantom 8-EX was definitely smoother than the SS.{S. Smith} 20-EX. Considering the relatively very flexible rear mounting of 8-EX and the increased power output at all speeds of the SS.{S. Smith}, the difference was not very pronounced. We consider that if 8-EX had been fitted with the original V.{VIENNA} series solid engine mounting there would have been little to choose between the two cars. The SS.{S. Smith} exhaust system at present makes it rather difficult to judge engine vibrations accurately, as it produces a number of audible periods in the body of the car. (3) STEERING. As we have previously pointed out, the SS.{S. Smith} steering as tested shewed no signs of a high speed wobble with tyre pressures of 25 lbs/sq.in; whereas the standard Phantom wobbled vigorously under these conditions. In addition to this advantage, with front tyres at 35 lbs/sq.in. and even at 25 lbs/sq.in. the SS.{S. Smith} steering definitely gave contd :- | ||