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).
Adopting and testing a Borg & Beck clutch for the Big Bore Bentley.
| Identifier | ExFiles\Box 129\2\ scan0112 | |
| Date | 19th November 1935 | |
| X1110 To BG. & WOT. c. to E.{Mr Elliott - Chief Engineer} c. to Hy.{Tom Haldenby - Plant Engineer} c. to Mx.{John H Maddocks - Chief Proving Officer} Borg & Beck Clutch. Big Bore Bentley. On the Big Bore Bentley we are adopting for the first time a Borg & Beck clutch. We are fitting a 10" clutch, the manufacturers say that this is on the small side for a car having a 4 1/4 litre engine. However, the car is of course no heavier than when a 3 1/2 litre unit was fitted. Another advantage of the 10" clutch is that it gives us a much smoother engine at high revs. than the 11" clutch, the next larger size available. The original Bentley clutch has undoubtedly given quite a lot of trouble in the hands of drivers who are not particularly expert, and occasionally, as in the case of Pedden, in the hands of accomplished drivers. For this reason we have subjected the big bore clutch to somewhat extensive tests. Attached is a report by C.W.H., from which it will be seen that for somewhat severe starting tests carried out on the level this clutch is considerably more durable than that fitted to the Buick, and infinitely more durable than the original Bentley clutch. To supplement this test we recently went to Devonshire and compared the latest R.R. design of clutch (as fitted to Lp{Mr Lappin}'s car for the last 50,000 miles and the Bentleys from 'E' series onwards) with the Big Bore unit. The test showed that the 10" Borg & Beck was approximately 30% the more durable, and that 100 ascents of Porlock, each ascent including 3 re-starts on the three steepest parts of the hill, could be made before 1/4 of the adjustment was used up. We also proved that with a full load the car could be re-started on the inside of the Lynton hairpin (1 in 3 1/2) without any difficulty whatever. | ||