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).
Investigating and rectifying excessive vibration in Mr. Johnson's coupe.
| Identifier | ExFiles\Box 25\3\ Scan062 | |
| Date | 21th February 1921 | |
| To P.N. from R.{Sir Henry Royce} c. to O.J. c. to Hs.{Lord Ernest Hives - Chair} c. to E.P. X634 R6/G21.2.21. X.634. RE. MR. JOHNSON'S COUPE. I had a short ride in Mr. Johnson's coupe, and noted the vibration that Mr. Johnson thought was excessive. I think this is nothing more or less than our old vibration due to the reaction of the cylinders shaking the frame. It can be reduced by still further lowering the compression(being sure that neither ignition is abnormally advanced) and it might be reduced by fitting leather, rubber, vulcanized fibre, or felt in the joints between the fame bracket, and the engine feet, with corresponding washers of the same materials under the bolt heads. I suggested this long ago, but it has never been definitely tested, and it might be an opportunity of doing so on such a marked case as this particular one. The vibration can be nearly avoided as you know, by only partially opening the throttle when passing from the lower speeds but as this spoils the vigour of the accelerator, it is not practiced by drivers who want to get along. The reason why it may be thought worse recently is because we are now fitting very gas-tight pistons, which naturally give vigorous effects. It would also be worse with new engines which may have tight fitting bearings, or tight fitting pistons. Engines which have been in use for a long time should be considerably smoother. This, we have all agreed is common knowledge, but I remarked it here in case they had been tightening up the bearings or (Contd:) | ||