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).
Road test findings for a vehicle's exhaust, ignition, and steering systems.
| Identifier | ExFiles\Box 4\1\ 01-page126 | |
| Date | 9th October 1934 | |
| -2- We believe, however, that to get Rolls-Royce slow speed pulling and idling we shall require the new short duration camshaft which has been designed. Exhaust System We have carried out tests on the exhaust system. This absorbs over 60 H.P. at 4,000 r.p.m. The main loss is in the rear silencer swan neck outlet and swan neck. The manifolds lose about 7 H.P. at the same speed. We do not think there will be much difficulty in modifying the silencer to overcome the restriction. The most satisfactory feature is that the method of bringing the two pipes from each bank of cylinders together does not seem to be responsible for any of this loss of power. Ignition The coils appear to get over hot in their present position on the engine, and the wax showed signs of exuding from both on the road. Further experience is required on this point. The ground set of timing gears that we are running are reasonably quiet. ROAD TESTS Steering The steering was the worst feature of the car. By comparing it with 27-EX - the previous independently sprung car which we built - we came to the conclusion that the road shocks were due to gyroscopic couples caused by the fact that the wheels on the SpectreCodename for Phantom III did not move in a parallel plane under spring deflection. The SpectreCodename for Phantom III of course exactly reproduces the Cadillac steering geometry, and the Cadillac people stated they had found this was necessary in order to get selective steering at high speeds, and good cornering. The Cadillac has no road shocks and therefore to reproduce their results we fitted a Cadillac type of steering to the SpectreCodename for Phantom III. This was actually one that we brought over from America with us. The results confirmed that with an irreversible steering, road shock can be eliminated. | ||