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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).
The performance and suspension of vehicle 18.G.IV after a 9,500-mile road test, comparing it to a Bugatti.

Identifier  ExFiles\Box 5a\3\  03-page167
Date  14th December 1931 guessed
  
To Hs.{Lord Ernest Hives - Chair}
From G.W.H.

Hotel de France,
Chateauroux,
FRANCE.

REPORT ON 18.G.IV. AT 9,500 MILES.

We have not at any period of the mileage come across any make of car, of the same horse-power, that has had the maximum speed of 18.G.IV. and that we could not overtake by judicious use of the third gear, the easy changing of the same with the quick acceleration being invaluable for traffic work. The only car, which we were not certain of its H.P., we believe it was a two-litre, which had a better acceleration on the level and on hill, was a Buggatti, which we followed purposely for some miles. On the hills our third gear speed was approx. 5 M.P.H. slower. On the level, direct drive, we were definitely faster over speeds of 40 M.P.H., being able to draw up to the car when we wished. On the level from 20 M.P.H. up to 40 M.P.H. we were slower. The maximum speed reached by the Buggatti was 70 M.P.H. The maximum speed that 18.G.IV. has reached under favourable conditions has been 87 M.P.H.

The springing of the car during the first part of the mileage was not considered good under any conditions. The front continually hit the buffers without any apparent cause and at high speeds the bumping was severe. The rear was good, from a passenger's point of view, up to speeds of 60 M.P.H., but from a view of safety, the brakes could not be applied heavily without the rear axle jazzing, with the rear of the car going anywhere. The front shock damper loads were increased first, which made the bumping less severe and of less frequency. We had a very severe skid during a morning's run whilst driving at 60 M.P.H., the car turning completely round twice, we therefore increased the poundage of the rear dampers for the rebound which gave us safe driving over any condition of road. We could also apply the full force of the brakes at 60 M.P.H. on a rough surface and the car was perfectly under control. It also definitely improved the steadiness of the steering at high speeds, but it definitely spoiled the rear springing from a passenger's point of view at speeds below 50 M.P.H. The results therefore, call for the speedy fitting of automatic progressive dampers, of Hartfords or hydraulics, which give a definite loading for town work or high speeds, is not applicable for the varying speeds of a touring car.
  
  


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