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).
Adjustment of shock-absorber friction settings to prevent high-speed steering wobble.
| Identifier | ExFiles\Box 71\3\ scan0316 | |
| Date | 7th September 1925 | |
| X8950 BJ14/DN7.9.25. FROM BJ TO Hs{Lord Ernest Hives - Chair} With reference to Hs{Lord Ernest Hives - Chair}3/LG1.9.25 in which you mention that whilst 103-MC was at the Works, you found the front shock-absorbers were set at 70 lbs. whereas the standard "W" setting is 30 lbs. - I have ascertained that a good deal of stress has been laid on the tightening of shock-absorbers in memoranda sent to Sales and all Depots, but these memoranda have rather indicated that the amount that the shock-absorbers are set up, should depend on each car and the effect produced, in order to prevent steering wobbles. No. 444 says: "Experience shews that the following points reduce the tendency for this high speed steering wobble to occur: (c). Extra friction on the front shock-absorber will tend to reduce the steering wobbles." No. 456 says: "(3) One must not be afraid of setting these to obtain plenty of friction". No. 462 says: "(3) Front shock- absorbers effectively tightened. (Within limits this latter is definitely an advantage for other reasons, especially on the 20 HP car)". PN{Mr Northey} made some tests on this car and found that the steering wobbles were distinctly lessened by tightening up the shock-absorbers on this car to the extent mentioned and until we had some better cure it seemed very necessary that every precaution should be taken during high speed demonstration runs, to prevent customers being scared stiff by an unexpected wheel wobble, which would in all probability lose the order for us immediately if it occurred. In regard to the wheels of this car being out of balance to the extent of 8 ozs., we are still investigating this matter, as the car had been sent twice to "N" to have the wheels balanced, and we were under the impression that this work had been carried out correctly. In view of the normal shock-absorber being set at 30 lbs., would it not be advisable to inform Depots &c. to what maximum extent you would suggest the friction might be increased to overcome these wheel wobbles? It would doubtless be of assistance to them if they knew whether your opinion was that the maximum should not exceed 40, 60, 80 or 100 lbs. B.J. | ||