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).
Letter detailing the fitting of new connecting rods and bearings to a Bentley chassis, including measurements, wear, and road test observations.
| Identifier | ExFiles\Box 27a\1\ Scan226 | |
| Date | 29th January 1935 | |
| 4013 To Hs.{Lord Ernest Hives - Chair} Derby Attention: Levallois Sr/VA8/ET.29.I.35 Re: BENTLEY LEAD BRONZE BEARINGS. Chassis B.I79.AE - M.{Mr Moon / Mr Moore} François EDMOND BLANC With reference to RHC.{R. H. Coverley - Production Engineer}2/MS/I2.I.35, we have successfully fitted the new connecting rods to this engine and must thank you for the clear instructions sent to us. Upon measuring up the crank pins of the crank shaft, we found them to be as follows: Nos. I, 2, 3 and 4 had a diameter of I.99775 ", " 5 and 6 " " " I.9975 ". Taking the original diameter of the crank pins as being I.999", it will be observed that Nos. I, 2, 3 and 4 pins had worn .00125" and Nos. 5 and 6 pins had worn .0015". Therefore, in view of the above wear, we had to make a special plug gauge with a diameter of 2.00025", to which we fitted the lead bronze bushes of the six rods. By leaving the lead bronze bushes a free fit on the gauge, this allowed a clearance of between .00275" and .003" between the bushes and the crank pins. We carefully ran in the bearings during the first road test and after running the engine progressively from medium speeds to high speeds, we noticed that the engine was a little on the stiff side or "tacky" when in a hot condition. However, we observed that after the final road test, the above had more or less worn off. The above answers the last sentence of paragraph 3 of your memo. Sr/VA. | ||