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 development and testing of front suspension systems, addressing issues of noise, material selection, and component failures.
| Identifier | ExFiles\Box 152\2\ scan0212 | |
| Date | 1st May 1940 guessed | |
| -5- 3. Front Suspension. This is not entirely satisfactory because it is spread over a large portion of the car, and it is, therefore, difficult to ensure that there will be no metal to metal contacts without having individual adjustments. From this point of view it is probable that the new wishbone suspension proposed for Myth will be a considerable improvement. These metal to metal contacts probably have an important bearing on the silence or otherwise of the suspension but this still requires proving. Some noise tests were carried out on 3.B.50. on the bumper drums. The modifications carried out were: Elimination of end play in front dampers, fitting of anti-squawk dashpots to the front damper valves, making the bonnet sides fit, and stopping the dash knocking. The coachwork mods. produced the most noticeable improvement in noise, and the car became reasonably quiet. There were at least two metal to metal contacts on the front suspension, the elimination of which ought to produce a further improvement. The silent blocs at the top of the yokes are subjected to considerable end thrusts, and are inclined to creep if the thrusts are always in one direction. Therefore the suspension should be assembled so that the yoke is central in the gap between the shock damper arms when the normal load is on the wheels. This means that on rebound the top end of the yoke will tend to move backwards and forwards on bump. The torque arms on production B.V. are steel forgings, but malleable iron castings are to be used on Ripplet. Aluminium castings have been tried but broke the first time. Strengthened aluminium ones are now ready for test. The Lower triangle levers on experimental cars are of cast steel. One of these broke on 11.B.V. during dismantling. Investigation showed that the metal was of very poor quality, and the laboratory carried out some tests to see if heat treatment could improve it. They found that the composition of individual castings varied so much that one heat treatment could not be used on all of them. Greater care must be taken when ordering castings. Production B.V's are steel forgings and are not suspect. The lower triangle levers on Ripplet should be able to be lightened considerably. On B.V's the spring deflections have always been 6.7", but 8.5" springs have been fitted to 4.B.50 and 11.B.V. with excellent results. 8" springs have been ordered for Ripplet and Rippletto, and will also be used on Bentlet. On 1.R.1. there was found to be a foul between the torque arm and the frame before full bump was reached because the rebound stop bracket on the frame was shaped wrongly. It was eliminated. This foul caused a most alarming crash on passing over quite small potholes, and all production B.V's complained of a similar noise. They were instructed to be modified in a similar manner to 1.R.1. During tests on 12.B.V. it was found that the full bump stops inside | ||