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).
Proposing modifications to the Wraith II front suspension based on learnings from the Phantom III to improve wheel movement and reduce tyre wear.
| Identifier | ExFiles\Box 95\2\ scan0023 | |
| Date | 14th February 1936 | |
| To BY.{R.W. Bailey - Chief Engineer} Copy to Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} Hs{Lord Ernest Hives - Chair}/Les.{Ivan A. Leslie} RHC{R. H. Coverley - Production Engineer} [Handwritten]: x346 E/Ev.{Ivan Evernden - coachwork}1/MN.14.2.36. [Signature] [Handwritten notes in left margin]: 10% reduction of stress in Spring & lever Wheel ø from 5° joggle T/2 [Typed text]: Wraith II Wheel Movement on Phantom III Front Suspension. The change of angularity of road wheels on bump and rebound of Phantom III is believed to be the cause of the peculiar front tyre wear and the source of steering joggle. It is proposed on Wraith II to overcome the difficulty by a modified ratio of length between the upper and lower wishbone levers and the centres on the yoke piece, so as to cause the wheel to stay more nearly parallel to the same plane. On N.Sch 4756, N.Sch 4757 and N.Sch 4758 we show a scheme for fitting special triangular levers and yoke piece to the present Phantom III suspension. Although this is of interest to us especially on Phantom III because of the reported steering joggles and front tyre wear, it is of primary interest to us as a means of obtaining advance information before we finally commit ourselves on Wraith II. We are fairly certain of the advantages to be obtained in connection with tyre wear and steering joggles, but we wish, by test, to confirm that the lower roll centre will not prove a disadvantage which will cancel the other attendant advantages. We would like this scheme tested on Phantom III as soon as possible. Due to the modifications in the leverage the stress in the road spring is reduced, which is another attendant advantage. Due to the lower roll centre the front roll rod may be required to be more effective, and to ensure this we have shown the roll rod with silent bush bearings, N.Sch.4763, with a rubber bearing link to the lower triangle similar to that which we have already issued for the standard Phantom III but with a longer connecting link. As it is necessary to make new bumb and rebound stops we have taken the opportunity of adopting the recommendations of the manufacturers that the rubber should be vulcanised on to a thin plate. A further advantage of this layout is that the brake geometry is improved. Ev.{Ivan Evernden - coachwork} | ||