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).
The testing of sample 10' clutch discs from Borg & Beck with variations in stop pin length and spacer arrangement.
| Identifier | ExFiles\Box 130\3\ scan0183 | |
| Date | 7th March 1941 | |
| To Dm.{D. Munro} from Em/GB. Copy to Em/AJH. EV.{Ivan Evernden - coachwork} EV{Ivan Evernden - coachwork}/Tln. Em/GB.1/SF.7.3.41. SAMPLE 10" CLUTCH DISCS from BORG & BECK. These discs were made after it was proved that the stop pins were of insufficient length to prevent severe local nip of the hub flange (see Em/GB.3/SF.31.1.41), resulting in wide variations in friction. In three of the discs, the stop pins were .005" longer than standard and, in the fourth, they were .017" longer. In addition, the number and position of the spacers was varied. The sample discs were identified by letters. They are described in the table below and compared with a standard disc. | | Stop pin length | .149 .146 | .154 .151 | .167 .162 | |---|---|---|---|---| | Arrangement of spacers (These are all .015" thick) | One on flywheel side of hub flange. | Standard disc | A.{Mr Adams} Red Springs | | | | Two on flywheel side of hub flange. | | B. Red Springs | A.{Mr Adams} Red Springs | | | One on each side of hub flange(Total 2) | | Red D.{John DeLooze - Company Secretary} Springs | Yellow D.{John DeLooze - Company Secretary} Springs | We know that a disc with a friction loop 17 to 27 lb.ft. deep has given us a rattle free transmission (with fully floating rear axle). It was hoped that the sample disc would have this depth of friction loop, but Messrs. Borg & Beck were unable to interpret friction in terms of stop pin length and spacer arrangement. None of the sample discs have sufficient friction and it would be wasting time to put any of them into a car without modification. However, the relative amount of friction in the different discs is what one might expect from a study of their specifications. | ||