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 bearing wear, with measurements taken and replacement work carried out.
| Identifier | ExFiles\Box 146\1\ scan0195 | |
| Date | 15th February 1938 | |
| Sr/VA2/ET.15.2.38 - 2 - The following work has, in the past, been carried out to the engine: On the 8.3.37, when the car had covered 7509 Kms., we removed the lower half, measured the sinkage of the main bearings, removed the original type liners and fitted a set of new liners in RR.56 metal to the main bearings and big ends and stepped the liners of the main bearings as necessary. Owing to the failure of N°4 big end bearing, we completely dismantled the engine on 2.4.37 (the car having then covered 8723 Kms), traces of metal from N°4 big end bearing having got into the oil passages in the crankshaft. We fitted a new connecting rod to N°4 and checked the main bearings and liners, which were found to be in good condition and re-erected the engine, which was quite up to standard on test. MAIN BEARINGS. We attach a photograph of the main bearings. The lower half of N°4 (centre) bearing is cracked. We measured the bearings for sinkage, which was as follows: 1 2 3 4 5 6 7 In upper half .004" .004" .004" .0065" .002" .005" .009" In bearing caps......... .0025" .0035" .003" .0045" .0025" .003" .0035" The bearings are in very poor condition and unfit for further use. They are very badly scored and Nos. 1, 4 & 7 have hammered in the housings, especially the upper half of the rear. As mentioned above, when the car had covered 7509 Kms., we removed the lower half and measured the amount of main bearing sinkage which was found to be as follows: 1 2 3 4 5 6 7 In upper half .002" .002" .003" .005" .002" .003" .003" In bearing caps......... .002" .003" .003" .003" .002" .003" .003" We fitted a set of liners in RR.56 metal to the main bearings and stepped them as necessary. We also fitted a set of RR.56 liners to the big end bearings. CONNECTING ROD BEARINGS. Although there is an average sinkage of about .002", the bearings are in good condition. We shall correct the sinkage by fitting "stepped" liners and leave the necessary nip. Sr/VA. | ||