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 clutch slip issues on 20/25 models, detailing causes and recommended procedures.
| Identifier | ExFiles\Box 130\1\ scan0071 | |
| Date | 12th October 1933 | |
| To Wgr. from Hs{Lord Ernest Hives - Chair}/Gry.{Shadwell Grylls} C. C. R.{Sir Henry Royce} C. Ds. Ev.{Ivan Evernden - coachwork} C. Hdy.{William Hardy} Ho. C. Dr. E.P. C MX{John H Maddocks - Chief Proving Officer} Hs{Lord Ernest Hives - Chair}/Gry.{Shadwell Grylls}6/RT.12.10.33. CLUTCH SLIP 20/25 - QUARTERLY COMPLAINTS. We have spent a few days at 'N' investigating this trouble. Recently on two of our own cars, GLW{Mr Wilde}-60 and 19-G-IV, we have experienced clutch slip; in both cases this was cured by several standing starts on top gear. We therefore analysed the clutch linings of customers complaints and found mineral oil absorbed in the lining. Slipping the clutch burns the oil off the lining. We consider that oil on the linings and tight splines are the two causes of clutch slip. The treatment of slipping the clutch at low speeds shows up immediately which is the cause. Either the pedal becomes very heavy due to the splines binding, or the trouble is cured. On the first car tried at 'N' clutch slip was apparent immediately outside the gate, but was of an intermittent character. On removing two out of the eight clutch springs the clutch would not drive at all. After a few standing starts on top gear it ceased to slip, and would still function perfectly with a further two springs removed, that is, half the total springs. Full throttle up changes, from 3rd. to top, could then be indulged in. We treated a further three cars in this manner and in each case cured the slip complained of. One of these had already been in for this trouble, and had been re-lined plus Ld.242 modification to splines. We recommend that this procedure is adopted. If of course the pressure ring binds, then more clearance is needed on the splines, and the clutch must be dismantled. If the slip is cured, then we do not consider anything further should be done. Excessive slipping should not be used. Four or five starts on a slight incline should be sufficient. If more than this is | ||