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 judder, its potential causes including ferrous coating on facings and engine mounting flexibility.
| Identifier | ExFiles\Box 129\4\ scan0205 | |
| Date | 28th April 1938 | |
| 1110 also 312 To By.{R.W. Bailey - Chief Engineer} c. to Da.{Bernard Day - Chassis Design} c. to Mx.{John H Maddocks - Chief Proving Officer} c. to Rm{William Robotham - Chief Engineer}/Wym.{G. Harold Whyman - Experimental Manager} Rm{William Robotham - Chief Engineer}/NRC.{N. R. Chandler}19/JH.28.4.38 CLUTCH FACINGS. Rm{William Robotham - Chief Engineer}/NRC.{N. R. Chandler}4/MH.{M. Huckerby}21.4.38. reports that examination at the Ferodo works, of the driven plate which had developed judder after 11,700 miles in B.56.BN{W.O. Bentley / Mr Barrington}, had the bonding wires steel coated on the flywheel side only, and in this instance there was no sign of coating on the cast iron pressure plate side. We would like to make it clear however, that this apparent ferrous coating can also occur with cast iron faces, and is very marked on a Phantom III driven plate recently received from N. We still think some other change occurs in the frictional properties of clutch facings, the nature of which is not yet known. There is also the question of the extent to which engine mounting may or may not be responsible for judder. We know that if, owing to too flexible mounting, the engine develops appreciable oscillation when pulling at between 500 - 1000 r.p.m. with the clutch fully engaged, an effect easily mistaken for a judder if the clutch were being engaged at the time, is produced, and it is between 500 and 1,000 r.p.m. that a slow start from rest is frequently made. With some of the earlier Wraith engine suspensions, the engine oscillated violently when accelerating from about 9 to 12 m.p.h. giving the impression of a clutch judder but on modifying the suspension to bring the engine period somewhere below 500 r.p.m. the judder disappeared, but we are still faced with some cases of judder which are due to the clutch because the only know remedy appears to be to fit another driven plate with new facings. Rm{William Robotham - Chief Engineer}/NRC.{N. R. Chandler} | ||