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).
Test report on steering wobble for chassis 93 NK at various tyre pressures.
| Identifier | ExFiles\Box 71\4\ scan0293 | |
| Date | 10th July 1925 | |
| Hotel de France Chateauroux. Indre. France. +S940 G.W.H./2/Crn.10.7.25. To: "Hs{Lord Ernest Hives - Chair}" From: G.W.Hancock. ---------------- Chassis 93 NK. We have again carried out tests with wheels unbalanced, approximately 1/4 lb. With tyres at 60 lbs. pressure. With this pressure at high speeds the steering is light. We do not mean by this expression that the steering is unstable, but that the car is easily deflected by running into a pot-hole, or striking a lump on the surface of the road. We could not produce the slightest tendency to wobble at speeds of 60 to 64 m.p.h. Also, shocks on steering wheel, going over a moderately rough road, were very slight. In fact, on this run, there was nothing at all to complain of with the steering. At low speeds, no sign of a wobble could be developed. The steering also had very little tendency to self centre, but the cambers of the roads are so erratic over here that we can not definitely rely on the self centering test. With tyres at 40 lbs. pressure. There were no signs of wobbles up to 58 m.p.h. From 59 to 64 m.p.h., we got a period where there was a strong inclination to wobble, but we could not get these to build up. Keeping at a speed of 60 to 61 m.p.h., they were continually coming and going, but at no time were there any which we should call violent. On the retard, there was a feeling of wobbles developing from 50 to 45 m.p.h. This was on retard only. We could not reproduce it when picking up through these speeds. The shocks on the steering wheel were definitely more pronounced with this pressure, than when tyres were at 60 lbs. On the other hand, taking the steering of the car all round, it was very much more comfortable to handle. With tyres at 20 lbs. pressure. We were able to get wobbles by starting them between 54 and 58 m.p.h., and they would build up rather violently, but by reducing the speed of the car, they immediately died out. None of these wobbles are of the kind that you spoke to me about. They are very similar to the low speed wobbles. The car generally, with this low tyre pressure, is very difficult to hold on the road. The steering is heavy, drags, car will not answer to the steering so readily, and on corners, at high speeds, one feels that the car is not going to get round. What is happening is that the | ||