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).
Technical analysis of vehicle gearbox slack, suspension rates, and steering characteristics.
| Identifier | ExFiles\Box 173\4\ img213 | |
| Date | 5th November 1935 guessed | |
| (sheet 3) splines, and the rear axle gear slack. They did not appear to worry much about the gearbox. Of the others, Packard went to great pains with the gearbox but not so much with the remainder of the transmission, and they had not cured the trouble but had to fit a dashpot on the accelerator pedal to avoid sudden closing of the throttle. Hudson also, in spite of their attention to rear axle clearance, had been compelled to fit a similar plunger, this time a petrol dashpot on the carburetter. Graham Paige's contention about flywheel weight, and also as to very large clearances having the desired effect, we were unable to verify. The general conclusion we came to was that attention to the slacks and especially slacks in particular places, was the most hopeful line of attack. It appears that slacks can be controlled to very fine amounts once the mass production cars do it. (3) Suspension. Olley's analysis of our suspension was principally concerned with the spring rates on the front, and after disagreeing with our results he arrived at the same conclusion as we did, viz. that the instantaneous rate at a given position is proportional to the square of the instantaneous lever ratio at that point. This of course is not a constant rate, and the investigation should be carried further so as to get a curve of suspension rate over the whole range. I have the necessary formula to do this analytically which Olley very kindly spent a considerable time in perfecting and checking, and the results can be compared with those we have already obtained graphically. It will be seen that the greater part of Olley's data applied to Phantom III seem to indicate that she will oversteer, and this Olley is confident is what is actually happening. Olley believes that in England we unconsciously like over-steering as it facilitates cornering, while in America the general preference is for a fairly definite amount of under-steering, the car requiring to be urged to change its course, and easily coming back into it. Other cars such as the Cadillacs which had over-steering characteristics in a much less degree than Phantom III were also less controllable, and it is suggested that the apparent discrepancy between these results may be explained by the height of the roll centre on Phantom III, and the construction of the frame enabling the shock dampers to work | ||