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).
The Paulin Bentley tests at Montlhéry prior to a publicity run, detailing a bearing failure and subsequent modifications.
| Identifier | ExFiles\Box 160\3\ scan0073 | |
| Date | 19th January 1939 | |
| 1379. Sg.{Arthur F. Sidgreaves - MD} from Rm.{William Robotham - Chief Engineer} Hs.{Lord Ernest Hives - Chair} c. Sr. Rm{William Robotham - Chief Engineer}7/R.19.1.39. PAULIN BENTLEY TESTS PRIOR TO PUBLICITY RUN. We have a report from France saying the best lap speed so far achieved by this car at Montlhery under very unfavourable conditions was 109.67 m.p.h. To achieve this speed with the gear ratio with which the car is equipped, it was necessary to use 6.50 x 19 tyres. In doing some repeat tests with standard tyres, i.e., 6.50 x 17, a big-end bearing failed. The car was being run continuously round about 4,500 revs. We attribute the failure to high revs., and the fact that thin oil was being used in a car which has already covered a very considerable mileage. Thin oil was used in order to get a good petrol consumption part throttle, but it is evident from these tests that we must not depart from our previous experience in the Tourist Trophy Race. We do not know the extent of the damage, but understand verbally that they will have no difficulty in re-building the engine with the spare parts which they have in Paris. It is quite evident, however, that if we are to contemplate running for 24 hours continuously with the high output available, it will be necessary to raise the gear ratio of the car. We have, therefore, despatched to Paris an overdrive gearbox which has been removed from 3.B.IV, an experimental car which is being prepared for sale. This will give us the correct ratio with the standard size of tyre, which will prevent the car looking abnormal, and keep the engine revs. down to about 4,000. We anticipate it will be the middle of next week before the car is on the road again. We are waiting to hear if the Italian roads are available before deciding where to go to re-hearse the press run. Rm.{William Robotham - Chief Engineer} | ||