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).
Test report on column vibrations and dash rigidity, comparing models 12-EX and 15-EX.
| Identifier | WestWitteringFiles\S\March1928-May1928\ Scan007 | |
| Date | 7th March 1928 guessed | |
| contd :- -2- strips of rubber buffer between the scuttle armature and the dash. The result was a 90% cure of column vibrations and rattles. We put the light stays back to relieve the scuttle armature as this was not designed to support the column. These improved the rigidity further. While making the tests we were very surprised at the flexibility of the cast dash, sitting on the wing one could observe it deflecting when un-supported, xx the centre could be moved appretiably by quite a moderate load on the radiator cap. A further slight improvement was made by carrying the tubular stay colum support higher up until it was just under the thrust race. We think that 15-EX suffered from this complaint because the column is considerably more raked than 12-EX, the car which has previously run 10,000 miles with a cast dash. Also 12-EX had a rigid fixing for the column where it passes through the dash - 15-EX had only a dust cover. We tried to make the dust cover into a rigid fixing but it did not seem to produce any result. Again the suspension of 15-EX is necessarily rather more damped than that of a standard car, which throws greater accelerations on the upper end of the column. It would seem advisable to lighten the upper end of the column as far as possible to reduce this effect. There is no doubt that on 15-EX the column requires a great deal of holding xx, but the car is continuing the 10,000 miles with the semi-isolation scheme and two light dashboard stays which run up to the level of the column stay attachment. Our experience is that we almost invariably improve both the scuttle armature and dash rigidity contd :- | ||