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).
Technical report on exhaust boom, valve springs, and connecting rod bearing issues.
| Identifier | ExFiles\Box 82\4\ scan0362 | |
| Date | 28th August 1936 | |
| -2- Exhaust Boom at Low Speeds. We have been working on this problem and believe we have a solution. The modification will be fitted to 34-BX when it is returned to Sales in 10 days' time. Valve Springs. We believe that the failures experienced have been explained by production troubles. At the same time we think we could with advantage have valve springs which are less highly stressed. We are testing some of these out, and at the same time Design are giving the matter their consideration. Connecting Rod Bearings. We have had the opportunity of looking at several sets of connecting rod bearings which have been doing ordinary road work, in particular those of 35-EX and 34-BX, which have been used for demonstration work. The bearings of 34-BX were exactly as at present fitted on production; i.e., white metal in Marine type rods. At 20,000 miles they were breaking up. They might possibly have done another 10,000 miles without complete collapse. The bearings of 35-EX were in much the same condition. It seems clear, therefore, that in the case of an owner who drives his car hard we may expect to have to renew bearings after about 25/30,000 miles' running. This will be particularly true of cars extensively used on the Continent. Our experience on the Bentley leads us to suspect that less than 5% of the customers drive really hard, and we therefore know approximately what our liabilities are likely to be. There is every reason, however, for pushing on with the test on Hall's metal big ends, and we are doing this as far as the capacity of the experimental shop will allow. If we have got far enough we may fit the parts to 35-EX after it has completed its London run before it is sent to France. | ||