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).
The causes and potential cures for steering wobble, including tire pressure and friction devices.
| Identifier | ExFiles\Box 20\2\ Scan106 | |
| Date | 7th October 1920 guessed | |
| Oy7-G71020 (2) Mr.Hulley who is skilled at producing wobbles in the way Mr.Hives describes, has been unable to produce them on badly wobbling cars after they have been fitted with this device. Before Mr.Hulley would sanction the fitting of this device, he checked up the lean of the pivots and the springs in the side steering rod, the tightness of the steering joints, etc. in every case. He and Mr.Caswell have also made the strongest campaign against hard tires, always recommending customers and chauffeurs to use 55 to 65 lbs. pressure rather than the 80 to 90 lbs. pressure recommended by tire makers. It seems to be fairly generally understood over here that the tire makers air pressures are not to be taken seriously. The cases of steering wobbles, rough riding etc. which we have complained of have not been cured by reducing the air pressure to 50lbs. or so; that is to say until there was a very marked bulge at the lower portion of the tire. With regard to Mr.Hives 3rd point - oscillation in the steering wheel on a bumpy road; we have not had complaints of this trouble except from new drivers who have not learned to hold the steering wheel loosely. With regard to Mr.Hives note on applying friction to the steering column, we have not considered this for a moment because we feel that it increases the shock loads on the steering mechanism. We feel that to introduce any friction here would be very dangerous on cars run under American road condition. With regard to Mr.Hives' note on the tests of the 500 type car, he will see from my report Oyll-G9820 on steering wobbles that we found there was much less tendency to wobble in the post war cars which had been fitted with wood wheels. I do not think this is the 500 type axle, but it is one in which we do not have centerpoint steering. Where Mr.Hives states that a friction in the pivot will cure very slight low speed steering wobbles, our experience is rather at variance with this. We find that the small amount of friction which we have introduced by the plunger in the stub axle, although so small that it cannot be detected in moving the steering wheel, is sufficient to cure wobbles on most new postwar cars with 33 x 5 cord tires. On old cars where considerable small slacks have developed all through the steering mechanism, and especially where they are fitted with heavy 35 x 5 cord tires, the friction is not sufficient to affect a complete cure. A considerable improvement in the tendency to wobble is noticeable, however, even in these cases. | ||