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).
Servicing costs and financial implications of cylinder bore wear and re-boring.
| Identifier | ExFiles\Box 132\5\ scan0097 | |
| Date | 3rd May 1939 | |
| 1/23 To: Rm{William Robotham - Chief Engineer} from BY/SB.{Mr Bull/Mr Bannister} c. to Rm{William Robotham - Chief Engineer}/CTS.{C. Trot Salt - Carburation} BY/SB.{Mr Bull/Mr Bannister}1/MG.3.5.39 CYLINDER BORE WEAR Rm{William Robotham - Chief Engineer}/CTS.{C. Trot Salt - Carburation}7/JH.28.4.39. We have interpreted your enquiry to mean - what basis is there for assessing any possible saving to the Company by improved cylinder life even if this means increasing the cost per chassis? To get a true picture of servicing costs incurred as a result of cylinder wear, it is necessary to spread the cost of complaint cases over the whole of our output, and the picture then becomes less depressing, because although the average mileage of those 4 1/4 litre cars which have been re-bored (which is the only available data) is around 35,000 miles, there are many more cars which have done much more than this without re-boring. Further, the Public are getting used to the idea that cylinders wear fairly quickly these days, and they are often prepared to pay for a re-bore at 35,000 miles, this being put forward now as a chargeable item at this mileage. Many people, however, quite naturally object to the idea of paying for a re-bore quite so soon, and, as it is difficult to substantiate on a car of this class, it often has to be done free of charge. The proportion of people who will pay for a re-bore at 35,000 miles is about 50%, which means that we do something like 80 re-bores a year free of charge. In most cases a bottom de-carbonisation is fairly chargeable at this mileage, so we only have to pay the difference between an R.20 and a re-bore, which amounts to about £4. although in some cases, of course, we have to pay the full amount. The total annual expenditure on free-of-charge re-bores is therefore some £350. In addition to this, we have to account for a number of cars which have high pressure scraper rings fitted early in their life, and this represents a further expenditure of about £150. per annum. Further, there is a number of cases where indirectly additional expense has been incurred in replacing big-ends which probably would have been good for further service had they not been disturbed. (continued) | ||