SPEED WOBBLE

Timaru Herald, Volume CXXXIV, Issue 18849, 11 April 1931, Page 14

SPEED WOBBLE

VARIETY OF CAUSES. There are, no doubt, many motorists who have never experienced speed wobble with their cars; and when first faced with this peculiar development, often in the short space of time devoted to wondering what has happened, allow the wobble to take complete control of the car, and maybe with serious results. A speed wobble is simply an unpleasant “wiggle-waggle” of the front wheels, but it usually develops without the least warning, and the disturbance is transmitted throughout the entire steering system, even up to the steering wheel itself. There is a cause for this trouble, which may be little known and one that few drivers ! —even many with considerable experi- | ence—would give a moment’s thought j to. Besides the common cause usually traced to worn joints in the steering | connections, it may lie directly with I the front springs. In this way if the j shackle bolts and their brackets have become over-loose through wear—and ; those on one spring may quite easily J wear down before those on the other—- , a degree of play may be readily introS duced. permitting one side of the front j axle to be less rigidly mounted than ! the other, with the result that the : wheel on the corresponding side has i too much movement. Naturally this undue play is inclined to develop as the speed of the car increases, until I at a certain pace it has reached and i passed the limit of safety. Then it I forces the other front wheel to join ' in the revolt, and so the w'obble com--1 mences. There is yet another likely reason ; for the introduction of speed w’obble, ! and one that is generally the fault of the motorist himself. For instance, it has often been proved to have been caused by excess lubrication. This fact, no doubt, will cause a little surprise, but nevertheless it has been found that over-lubrication of the steering joints of the stub axle, track rod, and other steering pivots may cause too free a movement; and, lastly, the practice of fitting unequally shod w'heels on the front axle (with one good tyre and the other the tread of which ha 6 w'orn down), is certainly asking for w'obble trouble. It stands to reason, the circumference of the good tyre naturally is greater than that of the worn-dow r n cover—producing, in fact, the same effect as unevenly sized w T heels on a single axle. As anyone may imagine, the larger wheel w r ill always be trying to overrun the smaller. Speed wobble starts, and unreliable steering results, since the driver’s attention must be devoted the w'hole time to correction of the bias of the larger w'heel, whilst when steering toward the side on w r hich the badlyshod wheel is mounted, unless extra care is taken, it wdll steer too readily that way, and may lead one into danger. On the. other hand, steering toward the side on which the efficiently shod wheel is fitted w r ill prove stiff and generally difficult. Yet, if any slackness in holding the steering wheel is permitted, the “wobbly business” immediately takes control. It is evident, therefore, that a speed wobble is something to be avoided at all costs.