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).
Investigation into the reasons why the Buick transmission is free from chunking noises when taking up the drive.
| Identifier | ExFiles\Box 124\3\ scan0317 | |
| Date | 22th February 1935 | |
| 43317 To Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} HS{Lord Ernest Hives - Chair}/GWH.{George W. Hancock - Head Chateauroux}18/KW.22.2.35. Buick Re Chunking in Drive. We have investigated the reason why the Buick is so free from chunking in the transmission when taking up the drive and running slow. The primary reason is because of the smooth engagement of the clutch, and solid mounting of the engine, which does not allow the torque of the engine to react on the engagement of the clutch friction. The absence of chunking when slow running or upon acceleration and deceleration is because of less driving pieces with their necessary slackness in the transmission. The driving shafts to the rear hubs have only splines which engage in the pinions of the differential, which in turn, any metallic noise is damped by the oil in the differential box. The shafts at the hub end are tapered and keyed, which cuts out slackness and metallic noises. With one cylinder cut out, leaving seven firing, the chunking noise is 50% less than what is heard on all our cars. The absence of chunking is not because special attention has been paid to obliterate slackness in the remaining portions of the drive, as the following measurements will show :- Slack in clutch splines - .007". Slack in synchromesh drive - .020". Total slack at drive end of third motion shaft .027". End play of third motion shaft - .007". Total slack in direct drive, measured at rear road wheel rim is .500". Slack in the differential pinions and driving shafts, measured at wheel rim, 5/16". Back lash in crown wheel and pinion, 1/16". | ||