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).
Engine modifications, crankshaft and bearings for the Chassis B.8.GA Paris Trials Car.
| Identifier | ExFiles\Box 146\3\ scan0285 | |
| Date | 30th December 1936 | |
| Sills Swell. 1020 .1245 To Bentley Motors Ltd. Derby............... Rm.{William Robotham - Chief Engineer} Copy to............. Sm. (Nice) Hd{Mr Hayward/Mr Huddy} Sr. is absent Levallois VAI/ET.30.12.36 Re: CHASSIS B.8.GA - PARIS TRIALS CAR Report upon bearings, crankshaft &c. Total mileage: 29.014 Kms. - Job N°35968 -------------------------------- We have dismantled the engine and carried out the following modifications: I - Drilled an extra and opposite hole in each main journal of the Crankshaft. II - Modified the grooves in the existing Hall's metal intermediate main bearings as per Rm.{William Robotham - Chief Engineer}244. III - Fitted an RR.56 rear main bearing and liners leaving .004" end float and .003" to .00325" clearance on diameter. IV - Fitted RR.56 liners to the remaining 6 main bearings, leaving from .00275" to .003" clearance on diameter. V - Fitted to new connecting rods complete with RR.56 big-end bearings and liners (shims). The engine is now being erected. The car is fitted with a large capacity oil pump. 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"247 : 2"2465 : 2"247 : 2"247 : 2"247 Ovality.........: .001 : .0005 : .0005 : .001 : .0005 : .0005 : .0005 CRANKPINS All crankpins have a diameter of I.9985". Please refer to attached sheet re "sinkage" of bearings and treatment of liners etc.. The following figures are the measurements, taken internally, of the existing main and original rear main bearings after the dismantling of the engine. Please refer to sketch. Before the measurements were taken, we stepped the upper faces of the original liners and reduced the faces of the caps corresponding to the amount of "sinkage"; so as to obtain as near as it was possible the true inner diameter of the main bearings. As you are aware, it is not easy to obtain this unless the "sinkage" is eliminated. | ||