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).
Specifications for fitting a set of connecting rods with Bentley bearings.
| Identifier | ExFiles\Box 146\3\ scan0180 | |
| Date | 19th November 1936 | |
| 1020 W/P. To Sr. from Rm{William Robotham - Chief Engineer}/Swdl.{Len H. Swindell} Rm{William Robotham - Chief Engineer}/Swdl.{Len H. Swindell}4/AP.19.11.36. BENTLEY BEARINGS. We are sending over a set of connecting rods which are fitted with R.R.56. bearings and shims. These have been reamed to 2.0008" diameter thus being suitable for a crankshaft 1.999" diameter. We do not know the exact diameter of the crank to which you will fit them but so long as they have a diametrical clearance between the limits of 1 1/4 to 2 1/4 thous. this will be O.K. The float between the crank and the rear main bearing bush in R.R.56 should be .003" to .004", the diametrical clearance as for Hall's metal .003" and if this is not strictly adhered to, it is better that the clearance be above rather below this figure. R.R.56 material has a much higher hardness figure than the standard Hall's metal and our experience up to now is that it is much better for not hammering out than Hall's metal in the rear main bearing. Rm{William Robotham - Chief Engineer} /Swdl.{Len H. Swindell} | ||