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).
Performance and handling report on a Humber car, comparing its components and road manners to a Rolls-Royce 20/25 HP model.
| Identifier | ExFiles\Box 182\M19\ img087 | |
| Date | 2nd June 1931 | |
| - 2 - The speedometer was checked and found to be correct at 20 and 30 m.p.h. and 3% fast at 40 and 50 m.p.h. All the performance speed figures given are by speedometer. The low speed performance is spoilt by carburation which is definitely weak between 10 and 18 m.p.h. and is sensitive to engine water temperature; a Stromberg vertical carburetter is fitted and the induction bend is water heated. Above 30 m.p.h. the performance is good. The Humber engine capacity (3498.5 cc.) is slightly less than our 20/25 HP. car; the top gear ratio is the same but smaller tyres are fitted. The engine appears very smooth throughout its range, although nearly everything is masked by a very bad induction pipe roar which makes the car very unpleasant at all speeds over 35 m.p.h. When at full throttle, the overrun is remarkably good, entirely free from vibrations and booms. The springing is very very bad, it is hard and pitches very badly; the springs were very well lubricated and there did not appear to be very much load on the Hartford shock absorbers. The steering being irreversible is entirely free from shocks and joggles, but it is rather heavy and does not self centre; it is not as selective as ours. It has a very good steering lock, 38 ft. turning circle as compared with our 48 ft (on R.H. lock.) The brakes are not at all pleasant; the pressure required on the pedal to overcome the pull off the springs is highly excessive, a small amount of additional pressure produces severe braking. It is almost impossible to apply the brakes easily and progressively. The hand brake operates the same system but has greater leverage, the result being much more progressive and very powerful braking. Self servo brake shoes are used, and as usual the steering control is affected by brake application. A silent third gear is used, which is very silent, and gear changing is easy. (The third gear slipped out into neutral on the overrun continuously.) Generally the car is very unpleasant because of springing and induction roar. Hs{Lord Ernest Hives - Chair}/Lid.{A. J. Lidsey} | ||