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).
Insufficient axle body damping and steering wobble on a 20 HP car, detailing modifications made.
| Identifier | ExFiles\Box 5\2\ 02-page242 | |
| Date | 1st April 1929 | |
| 75830 Re. DA.{Bernard Day - Chassis Design} BY.{R.W. Bailey - Chief Engineer} from R.{Sir Henry Royce} c. to SG.{Arthur F. Sidgreaves - MD} Mor. E.{Mr Elliott - Chief Engineer} c. to PH. EP.{G. Eric Platford - Chief Quality Engineer} R1/MS.4.29. G3. PROPOSE 10,000 MILES 20 HP. BROUGHT TO LE CANADELHenry Royce's French residence BY REYNOLDS AT EASTER WITH MR. McDONALD. X.5770 X.5430 X.5830 X.5840 X.5520 INSUFFICIENT AXLE BODY DAMPING. The Hooper body is rather too high and unnecessarily heavy. The latter can be judged by the weight of the doors. DIVEV. will say how much this type of body should weigh for a 20 HP. The over-weight of the body I think is principally due to the heavy construction of the windscreen, and doors. The road springs were hardly stiff enough for the weight but not very wrong as a town carriage, on fairly good roads. Without very much trouble we were able to increase the recoil damping (downwards - high pressure) by 50% by taking out the .072 washer from under the plug, and adding a .036 washer to the length of the spring. We did this because the 20 HP. is insufficiently damped. The rear dampers were taken off and found to be otherwise quite in order, and of my favourite type. The upward damping should also be increased. I feel certain that our 20 HP. damping must be increased by 50% total effectiveness, and the upward about 50% of the downward. There is another feature which for years I have been promised, has been corrected: it is the steering arm, which is wrong and ugly in shape. The increased damping was a very definite improvement but I should like to have a little more upward poundage. But I only ask this because it now seems only about 30% of the downward. Actually the car now rides so well that one cannot hope for much improvement. The front strikes the buffers occasionally on these very bad roads. STEERING. Previous to touching the dampers we had on 2 occasions low speed (17/18 m.p.h.) steering wobbles, which came on at a level railway crossing, and again at a turn on a rough road. Then after several tries we could get it every time at the above m.p.h. There was absolutely nothing to be found wrong, and no change could be made unless the pivot lean were reduced a little more than 1º by taking out the taper packing (taper about 2 ms. in 3"), and putting in contd .. | ||