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).
Possibility and method of changing main bearings on a Bentley 3 1/2 litre chassis without removing the engine.
| Identifier | ExFiles\Box 146\2\ scan0008 | |
| Date | 6th January 1937 | |
| Swell. Please talk over with shop & discuss with me. Rm.{William Robotham - Chief Engineer} (Handwritten) To Bentley Motors Ltd. Derby. Copy to .....HU. ..................Rm.{William Robotham - Chief Engineer} Levallois Re: MAIN BEARINGS BENTLEY 3 I/2 LITRE CHASSIS During the conversation we had with GWH.{George W. Hancock - Head Chateauroux} last Monday concerning the contents of our memo Sr/VAI/MLG.23.12.36 in connection with Bentley 3 I/2 litre bearings, he mentioned that the Works have under consideration the possibility of changing an intermediate or intermediate bearings, without removing the engine from the frame. We have now been studying this question ourselves and, as far as we can see, we think this can be done and a satisfactory repair job be made. In order to change one or more of the intermediate bearings, we should naturally have to lower the crankshaft sufficiently to remove the upper half of the bearing from its dowel. It appears to us that the main difficulty in fitting a new upper half main bearing would be to make sure that the joint faces of the new bearing are flush with the corresponding machined shim face of the crankcase. This, however, can be overcome by making a special gauge tool for the job. The gauge we have in mind would be in form something similar to a lower bearing cap with adjustable shim faces (in the vertical plane) at each side of the gauge. The original upper bearing would be placed in the gauge, which would have a dowel similar to the ones in the crankcase; the adjustable sides of the gauge would then be brought level by a screw arrangement with the joint faces of the original bearing; the adjustable sides would then be locked in position and the bearing removed. The joint faces of the new bearing to be fitted would then be reduced to the same level as the shim face of the gauge. Before the fitting of a new bearing, we should naturally have to reamer them to the size required. As we have a spare upper half crankcase and Martell reamer, this should not present any difficulty. We shall be glad to have your opinion re the above. Sr/VA. | ||