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 carried out on the 58-GN car at Derby.
| Identifier | ExFiles\Box 18\3\ Scan356 | |
| Date | 8th September 1932 | |
| To Sg.{Arthur F. Sidgreaves - MD} from Hs.{Lord Ernest Hives - Chair} C. Wor.{Arthur Wormald - General Works Manager} C. E.{Mr Elliott - Chief Engineer} Ry. x7960. Hs.{Lord Ernest Hives - Chair}10/AD8.9.32. 58-GN CAR The following modifications were carried out to this car at Derby :- (1) Compression ratio increased from 4.8 to 5.25. This is the compression ratio which has been standardised for Continental cars. The proposal is that we may adopt this for all cars. (2) New camshaft having higher lift and longer duration. The advantages of this camshaft are only apparent when we use the new semi expanding carburetter. Without the new carburetter the power output of this camshaft is not as good as with the standard camshaft. (3) Semi-expanding carburetter. The carburetter which we fitted to your car is identical to the one run on 19-EX in France. The mixture control is set to run in the normal position in the centre. It is very possible we shall have to modify this and that the normal position will be on the full weak side and that there will be no control for weakening the mixture but the full control will be used for starting and getting going with a cold engine. (4) Exhaust. This car is fitted with a resonant type silencer. It is proposed to standardise this for P.II cars. (5) The clutch springs have been made stronger and the leverage modified so that the pedal pressure remains the same. (6) A proportion of front braking has been increased. (7) Steering. We have added to the steering a friction device on the column. 58-GN car is bad for steering joggles. To prove the advantage of the friction on the column it is only necessary to slack off the bolt holding the large diameter disc and screw it back 2 or 3 turns. The position should be marked so that it can be put back in the same place. The limit of friction will be that which can be tolerated when running under London conditions. With such a device, of course, it would be possible when touring at high speeds in France to screw it up tighter than normal and so reduce joggles to a minimum. | ||