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).
Testing and proposed solutions for a slow speed steering wobble on a 20HP model.
| Identifier | WestWitteringFiles\T\March1929-December1929\ Scan088 | |
| Date | 19th April 1929 | |
| HS.{Lord Ernest Hives - Chair} DA.{Bernard Day - Chassis Design} ) FROM R.{Sir Henry Royce} (At Le CanadelHenry Royce's French residence.) C -- SG.{Arthur F. Sidgreaves - MD} WCR. -- ? (strikethrough) " " PN.{Mr Northey} CV (strikethrough) 20HP. STEERING. X5430 I admit that the slow speed wobble was very difficult to get by hand, but on 3 occasions came on unintentionally by the rough road, and level crossing (oblique), and only at 17 MPH., though it was dangerous and alarming. (Probably improved oiling had some effect.) After we learnt how we could produce it I asked Dodd to test, as far as we were able, the following: (1)...... If the lateral stiffness of the frame had any effect by tightening and slacking the engine dampers. Result - No. (2)...... If more or less friction on the cross steering tube. Result - No. (3)...... If higher or lower pressure in the tyres. Result - perhaps high pressure more liable. (4)...... We then examined the lean of the pivots and reduced it about 1 1/2° when a thorough cure was effected, and much improved general steadiness of steering. This was the surprise of the test. The taper packing was entirely removed and parallel ones fitted. Also the increase in the hydraulic dampers made poor riding quite good, and only an occasional bump on the front rubbers. Something effective should be done - (1)...... Reduce the lean to the same as Phantom - i.e. from probably over 3° to 1 1/2° to 2°. (2)...... Provide some simple means of checking the lean, probably a flat on axle for spirit level or straight edge. (3)...... Increase the size of the cross steering ball so that the friction can be more and more effective, but much of this is bad and would lead to introducing more lean. (4)...... Find out if the road wheels with less centre point as new axle instructed, has any effect on low speed wobbles. If I remember rightly it has not, but is very effective in high speed wobbles. R.{Sir Henry Royce} | ||