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).
Clutch slipping issues on high compression 25 HP cars, attributing the problem to using springs from the 20 HP engine and outlining the torque increase that necessitates stronger springs.
| Identifier | ExFiles\Box 5\6\ 06-page063 | |
| Date | 6th February 1930 | |
| To Oa. From Hs{Lord Ernest Hives - Chair}/AJL. c. to Sy. X 5300 Hs{Lord Ernest Hives - Chair}/AJL.1/M.{Mr Moon / Mr Moore} 6.2.30. X.5300 X.5770 X.5771 CLUTCH SPRINGS ON HIGH COMPRESSION 25 HP. CAR. We are experiencing considerable trouble with clutches slipping on the 5.25:1 compression 25 HP. cars. Trouble is also experienced but to a lesser degree on the standard 25 HP. car. On looking into the matter we find we are still using the same clutch and clutch springs as were used on the original 20 HP. engine. The troque increase is considerable over the original 20 HP. and it is necessary to strengthen up the clutch springs to obtain the same freedom from slipping. When changing over from small bore to 3.25" bore the torque increase was at its maximum at 750 R.P.M. and was in the region of 26%. The second change to 5.25:1 compression ratio has given us a maximum increase in torque at 1000 R.P.M. of 35.8% over the original 20 HP. engine. We have had to increase our clutch spring load as a temporary measure by packing up the existing springs on the two high compression 25 HP. cars. The job is rather urgent as a high compression car is leaving for 10,000 miles test in about a week and should be fitted with modified clutch springs. Hs{Lord Ernest Hives - Chair}/AJL. | ||