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 memo detailing crankshaft measurements and procedures for fitting new bearings.
| Identifier | ExFiles\Box 146\2\ scan0231 | |
| Date | 7th June 1937 | |
| Sr/VA3/ET.7.6.37 - 2 - CRANKSHAFT : 1 : 2 : 3 : 4 : 5 : 6 : 7 Maximum dia- : : : : : : : : meter of main: : : : : : : : journals.... :2"248 :2"2475 :2"2475 :2"2475 :2"2475 :2"2475 :2"2475 Minimum dia- : : : : : : : : meter of main: : : : : : : : journals.... :2"247 :2"247 :2"2465 :2"247 :2"247 :2"247 : Ovality..... : .001 : .0005 : .0005 : .001 : .0005 : .0005 : .0005 CRANKPINS - All crankpins have a diameter of 1.9985". It is possible that, when we next dismantle the engine in order to fit the new main bearings, which you propose to send us, we shall find a certain amount of wear on the main journals. The journals were also scored the last time we examined them. In order that the new main bearings may have the best possible chance, it is necessary that the crankshaft should be in a reasonably good condition when the new bearings are fitted. We have in the past had the main journals of two crankshafts (3 1/2 litre Bentley) ground to .010" undersize and re-nitrided. The nitriding, although not expensive, is a long job. As a guide, will you please let us know when you consider that a crankshaft should be re-ground. This information will be very useful to us. As soon as the cylinders are dismantled, we shall measure the bores and, if necessary, regrind them and fit o/s pistons. If the main journals of the crankshaft need regrinding to .010" undersize, then the new main bearings would have to be of a size to suit. We think you are aware that we possess a Martell reamer and the necessary tackle that goes with it. Please also let us know the clearances of the new bearings. Sr/VA. VA | ||