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).
High-speed steering wobbles in 'V' series cars.
| Identifier | ExFiles\Box 28\4\ Scan280 | |
| Date | 17th August 1925 | |
| R.R. 438a (50 H) (D.D. 31, 12-6-25) J.H.D. EXPERIMENTAL REPORT. Expl. No. REF: Hs{Lord Ernest Hives - Chair}/Rml/LG17. 8. 25. HIGH SPEED STEERING WOBBLES. We have been carrying out continuous experiments with regard to this phenomenon. Our general impressions with regard to these wobbles on EAC. 'V' series cars are as follows :- By far the most alarming high speed wobble is that which takes place below 60 m.p.h. The lower the period of the wobble, the greater its amplitude, the greater its effect on the driver, and the more uncontrollable the car. The worst wobbles we get are almost always on the overrun. These are invariably at a lower speed than the corresponding wobble when the car is accelerating, they therefore have a greater amplitude and a greater tendency to build up. As an axiom we may therefore say that anything which tends to lower the period of a wobble without otherwise materially effecting it, is going to make the wobble much more unpleasant for the driver. By this we mean that a balloon tyre in our experience, reduces the road speed at which a wobble takes place, the exact amount depending on the pressures used. We should therefore expect a car which wobbles badly with high pressure tyres to be uncontrollable with low pressure tyres because the road speed at which the wobble comes on is considerably reduced. This is not the case, however, to the extent anticipated because the 8" balloon tyre and wheel weigh 13% less than the straight-sided tyre and wheel and hence reduce the transverse moment of inertia of the axle. contd :- | ||