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).
Test drive report and analysis of suspension adjustments for chassis WRB-21 to improve ride quality.
| Identifier | ExFiles\Box 109\5\ scan0175 | |
| Date | 6th June 1939 | |
| W/S. (C). from BY/SB.{Mr Bull/Mr Bannister} c. BY.{R.W. Bailey - Chief Engineer} c. Rm.{William Robotham - Chief Engineer} c. W/N. (Br.{T. E. Bellringer - Repair Manager}) c. LA.{L. A. Archer} c. Hd.{Mr Hayward/Mr Huddy} 661. A-T-M BY/SB.{Mr Bull/Mr Bannister}11/G.6.6.39. CHASSIS NO. WRB-21. SIR RALPH MILLBOURN. I took this car back to Sir Ralph at Middleton yesterday, after completing various alterations to the springs and dampers, and at his suggestion rode in the back with him up to London where he had some business to attend to. He remarked at once on the great improvement, but said he would reserve judgment until we got to the Pulborough - Five Oaks road, which would be the worst test. Just before getting there, however, he fell asleep, and I deemed it best to leave him to see whether the excellence of the ride would permit him to sleep over the worst section. He did not wake up until we reached Wimbledon, and he was then so pleased with the general result that he said after all it was a nice motor car, he would keep it and dispose of the Austin. His chief grievance now concerns the amount of inconvenience he has been put to. Would you be good enough to write him, as he would appreciate a nicely worded letter from you following this report. The main point in developing the ride of this particular car is that we have had to get away from the idea that the so-called sea-sickness was due to ultra-softness in the suspension, and that we must therefore stiffen it up. It was probably not this form of sea-sickness at all, but another form of illness which was caused by rapid vertical acceleration and the large amplitude of displacement of the body due to pitching. The low rated front springs and roll bar did not effect a large improvement because they tended to aggravate the out-of-phase, which existed between front and rear. We therefore brought the rear periodicity down by fitting lighter rear springs, the periodicities then being 64 front, 84 rear. There was still far too much movement, but from this point onwards it was only a matter of finding the best shock damper settings. The final result was gained by setting up the rear dampers to 100 lbs. initial load. As this car represents one of the worst examples of heavy and overhung bodies, we have had on the Wraith, it would appear that we need no longer fear that this type of body must produce a bad ride. Provided the spring ratings are correct, we have ample range of shock damper adjustment to cater for any type of body. | ||