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).
Engine vibrations and distributor failures, particularly following high-speed tests in France.
| Identifier | ExFiles\Box 108\3\ scan0161 | |
| Date | 23th March 1938 | |
| 600a. Sg.{Arthur F. Sidgreaves - MD} from Rm.{William Robotham - Chief Engineer} Hs.{Lord Ernest Hives - Chair} c. Hy.{Tom Haldenby - Plant Engineer} c. Da.{Bernard Day - Chassis Design} c. H.C. c. MX.{John H Maddocks - Chief Proving Officer} c. Hy{Tom Haldenby - Plant Engineer}/RD. c. Rm{William Robotham - Chief Engineer}/BC. ENGINE VIBRATIONS & DISTRIBUTOR FAILURES. If we consider the car which has run 15,000 miles in France, the only damage caused by the high speed engine roughness has been distributor failures. Our immediate objective, therefore, has been to find a way of stopping this vibration getting to the distributor, so clearing production. The attached report indicates that the spring drive, which was designed as a result of the French tests, should overcome the trouble. Unfortunately, this spring drive was originally designed for the Delco distributor, but another design has been produced for the R.R. distributor, which, as will be seen from the attached note from Waller, has been suffering from the severe handling it has received. There is still some mystery as to how the vibration is produced so easily on the car in France, because our experiments have so far cost us 7 big-end bearings, 3 clutches and one piston, though we have avoided completely smashing up an engine. We have also had to run 8 1/2 hours at round about 4,400 revs. to achieve the present results. We have so far refrained from running a 25/30 engine like this because we know that the Wraith big-ends have about five times the life of the old 25/30; it is almost certain that we should smash up a 25/30 engine if we treated it in this manner. We have measured the oscillations taking place on the nose of the crankshaft by means of an indicator, and these are severe, but we are not sure that they are the direct cause of the trouble, nor do we know how to eliminate them. We have tried to detect a difference between the behaviour of the 25/30 and the Wraith engine distributor drives by various means, but without success. The investigation is proceeding. In the meantime, raising the axle ratio on production has made it less easy to reach the rough period in top gear. RM.{William Robotham - Chief Engineer} | ||