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).
Analysis of connecting rod crankshaft pin measurements and a report on suspected conrod flapping from a 3½ Litre Bentley.
| Identifier | ExFiles\Box 83\1\ scan0224 | |
| Date | 25th September 1936 guessed | |
| (4) (3) The connecting rod crankshaft pins are good as follows. 1 2 3 4 5 6 1.99825 1.9985 1.999 1.9985 1.99875 1.9985 1.998 " " " 1.9985 From our investigation it would appear that the Hall's metal is too hard for the crankshaft journals causing grooving of the steel surface. The continual hammering effect causes fidgeting of the bearing in the housing which in turn causes a powdering effect between the two metals, mostly on the aluminium. The bearing should be a very tight fit in the housing and located definitely. The shims should be cut out altogether. (4) Suspected flapping of conrods. We were able to examine a set of conrods taken out of a 3½ Litre Bentley after 32000 klms. The following is what was noted. All the conrod bearings had a bright polished surface on the side towards the front of the engine, none looking towards the flywheel. The crank pins showed rubbing on the flanges looking towards the front of engine. No marks looking towards flywheel. This indicates a thrust of the crankshaft towards rear of car. > Front of car 6-B-IV are similar. | ||