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 report on the gearbox, rear axle, suspension, tyres, and general performance of a test vehicle.
| Identifier | ExFiles\Box 109\4\ scan0132 | |
| Date | 11th July 1939 | |
| -4- Rm{William Robotham - Chief Engineer}3/R.11.7.39. GEARBOX. It must be appreciated that whilst we have finished the development of the universal gearbox for the six-cylinder engine, we have not yet brought this box to a stage where we can expect it to be reliable with the 8-cylinder power plant. To match up with our dynamometer tests, it will be exceedingly useful to see what failures occur during this run on the 'Silver Phantom'. In spite of the gruelling time it received in the mountains, no trouble whatever was experienced with the transmission during our run. The gear ratios appeared to be exactly right, second speed being adequate for any Alpine main road gradient. This particular box has a good standard of silence. REAR AXLE. There was no indication of rear axle trouble during the run. SUSPENSION. During the very hot weather, the dampers seemed to lose some of their effectiveness. It may be that on these very large and fast cars we shall get a very definite advantage with controllable front damping. The only real criticism we have of the suspension of 30-G-VII is that it hit the buffers rather easily, but the car was not, of course, being driven as a town carriage. TYRES. 7.50 x 16 4-ply rayon tyres, produced by Dunlops, were used on the car. The ride at low speeds is very sensitive to tyre pressures, and to get the best results we let down the front tyres to 24 and the rear to 26. Before doing high speed work we inflated them 10 lbs sq.in. No failure occurred. The tyre treads became very noisy after 2,000 miles. PERFORMANCE. The general touring performance of the car was certainly better than that of the P.III. The top speed in | ||