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).
Steering geometry, spring stiffness, and shackle fit in comparison to the Silver Ghost model.
| Identifier | ExFiles\Box 154\3\ scan0018 | |
| Date | 11th April 1927 | |
| Oy3-E-41127 -2- April 11, 1927. inclined spring is a new condition tending towards a lack of perfect geometry in the steering, although it is still a better geometry than the Silver Ghost with the shackle at the rear. (2) We think however that with the shackle in front it will be found that the steering restlessness improves as the front springs are softened. (This is the reverse of experience on the Silver Ghost with the rear shackle.) We are working to R's recommended "lower limit" in springing, i.e. the front spring stiffness, when clipped to the axle, is 30% of the applied load. This is probably just a little softer than Silver Ghost non-front-brake practice where the stiffness was 28.5% on the unclipped spring and probably 31.5% when clipped to the axle. (A general opinion is that the new cars with F.W.B. ride a little better than the Silver Ghost without F.W.B. We do not get swerving when braking when the front brakes are properly equalized.) (3) It is possible that the slack fit - 1/16" slack, in the rear serrated shackle may have some effect both on high speed wobble and on restlessness of the steering, since it allows some fore and aft movement of the springs and axle, though this is constrained by the load on the spring. Whether this slack fit is to the advantage of the steering or otherwise we do not know, but we are making some close-fitting shackle bushes to find out, and will let you know the results. Yours very truly, Maurice Olley MO/E | ||