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 performance and drawbacks of a new overdrive gearbox.
| Identifier | ExFiles\Box 83\2\ scan0157 | |
| Date | 13th December 1937 | |
| Send a copy of this note to By.{R.W. Bailey - Chief Engineer} Sg.{Arthur F. Sidgreaves - MD} c. to Hs.{Lord Ernest Hives - Chair} c. " C. c. " Rm.{William Robotham - Chief Engineer} 6-B-IV Cx{Major Len W. Cox - Advertising Manager}8/KW13.12.37 250cc I have had an opportunity now of trying this car, primarily to give a report on the overdrive gearbox, and I can say at once from my own experience with this car that so far as performance goes - and in performance I include starting from rest on 1st or 2nd speed and the maximum speed attainable with the car on its highest gear - it is unquestionably superior to the present standard product, and I much prefer the car with the overdrive ratios. One has only to drive this car for some time on the overdrive gear, and then at 60 or 70 m.p.h. change down to the direct drive to realise how much nicer and smoother the engine is on the overdrive ratio. Quite an appreciable amount of 'fuss' and vibration are eliminated in a most pleasing way. For normal driving under general conditions the ratios of all gears seem to be a very good compromise, and bearing in mind the objects that the Works are aiming at. There is however I consider one serious drawback to the proposed box, and that is that as soon as a gear lower than the direct drive is required there is no s/mesh. The absence of this feature, I think, will in the opinion of users neutralise some of the advantages to be obtained from this box, and I think it would be with them a feature creating keen disappointment. Directly I discovered that the second gear had no s/mesh my enthusiasm for this box was considerably damped. The change from direct drive to second, which is a bigger reduction than the change from the old 3rd speed to 2nd, requires an operation which most motorists have forgotten about to-day, i.e. a rather accurately timed double clutch change, and I think it is extremely important the Works should try and incorporate a synchro-mesh scheme in this gear. Cx.{Major Len W. Cox - Advertising Manager} | ||