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).
Diagnosing the cause of wheel wobble and illustrating a method of correction.
| Identifier | ExFiles\Box 38\1\ Scan168 | |
| Date | 12th June 1925 | |
| R.R. 493A 150 H (D.D. 31. 12-6-25) J.H.D. EXPERIMENTAL REPORT. Expl. No. REF: Hs{Lord Ernest Hives - Chair}/Rm{William Robotham - Chief Engineer}2/LG161025 To RG.{Mr Rowledge} from Hs.{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} WHEEL WOBBLE. There are two kinds of wheel shimmy quite separate in cause and cure. A low speed wobble occurs at speeds below 30 m.p.h. and is usually worst at about 15 m.p.h. A high speed wobble which occurs at 50/60 m.p.h. with low pressure tyres and 60/75 m.p.h. with high pressure tyres. We conclude that your trouble is a low speed wobble. The most important factor in low speed steering wobbles is the transverse inclination of the steering pivot viewed from the side of the car. In order to make the steering self-centre, the top of the steering pivots are inclined towards the rear of the car as in the illustration :- This inclination is obtained by inserting a wedge between the spring and the axle as in illustration (2). If the backward lean of the pivot top is too great, the car contd :- | ||