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).
From Detroit discussing torsion bar and wishbone suspension designs, with reference to Olley's opinions and the Phantom III model.
| Identifier | ExFiles\Box 173\4\ img136 | |
| Date | 27th November 1935 | |
| COPY (Memo. from Da.{Bernard Day - Chassis Design}) DETROIT. 27.11.35. To E.{Mr Elliott - Chief Engineer} from Da.{Bernard Day - Chassis Design} I received your cablegram re torsion bar suspension and have cabled that Olley sees no objection to the parallel torsion bar suspension with wish-bones, as such, but thinks we must have unequal links, so that the outer wheel may be pulled up straighter on a roll. He says, however, that he would not use a ratio between the bottom and top overs of 2 to 1 if he were doing the job again, but some less ratios, though exactly what of course he cannot say. He says this straightening up of the outer wheel on a roll is the only real advantage of the wish-bone suspension. Bringing the engine forwards and using a single steering lever are only incidental and not fundemental advantages. He also says however, that so far they have not succeeded in making torsion bars stand up as well as coil springs, but attributes to Cadillacs not knowing as much about spring making as the regular spring makers. From what I remember of the job there seems no reason why we should not have unequal links with a ratio say of 1.5 to 1 using a torsion bar parallel to the centre line of chassis. Olley says the shock damper whether on the upper or lower wishbone, must be solid with the suspension, that is, not connected with it by a connecting rod, or any-thing of that sort. The bolt centre can be raised by suitably inclining the wishbone so long as it is not overdone. Olley will give me some figures about our suspension very soon. I said, by the way, that he had discovered that our rating at normal was not what we supposed, but he has now admitted that he had made a mistake, and on further consideration agrees with our results though he has worked them out in his own way, so that our normal deflection of 7" is correct. The slight reduction of castor which may result from using inclined wishbones is not now put forward as a real advantage, the self centring characteristics of the independent suspension being so much greater as to swamp it. As regards the Phantom III suspension Olley thinks we shall not be able to stand so much "swing axle" effect (as he calls it, meaning the wheel swinging like a conventional axle about some centre near the other wheel), because of the wheel-fight. The steering characteristics of our car seem however to be much better than any car they have here, in spite of the apparent lack of stiffness of our frame, and it seems a pity to run the risk of losing any of this unnecessarily. In addition it will be rather difficult to modify this | ||