40 --- Directional instability
Steering head bearing adjustment too tight. This will cause rolling or weaving at low speeds. Re-adjust the bearings.
Steering head bearings worn or damaged. Correct adjustment of the bearing will prove impossible to achieve if wear or damage has occurred. Inconsistent handling will occur including rolling or weaving at low speed and poor directional control at indeterminate higher speeds. The steering head bearing should be dismantled for inspection and renewed if required. Lubrication should also be carried out.
Bearing races pitted or dented. Impact damage caused, perhaps, by an accident or riding over a pothole can cause indentation of the bearing, usually in one position. This should be noted as notchiness when the handlebars are turned. Renew and lubricate the bearings.
Steering stem bent. This will occur only if the machine is subjected to a high impact such as hitting a curb or a pothole. The lower yoke/stem should be renewed; do not attempt to straighten the stern.
Front or rear tire pressures too low.
Front or rear tire worn. General instability, high speed wobbles and skipping over white lines indicates that tire renewal may be required. Tire induced problems, in some machine/tire combinations, can occur even when the tire in question is by no means fully worn.
Swinging arm bearings worn. Difficulty in holding line, particularly when cornering or when changing power settings indicates wear in the swinging arm bearings. The swinging arm should be removed from the machine and the bearings renewed if adjustment does not cure the fault.
Swinging arm flexing. The symptoms given in the preceding paragraph will also occur if the swinging arm fork flexes badly. This can be caused by structural weakness as a result of corrosion, fatigue or impact damage.
Wheel bearings worn. Renew the worn bearings.
Tires unsuitable for machine. Not all available tires will suit the characteristics of the frame and suspension, indeed, some tires or tire combinations may cause a transformation in the handling characteristics. If handling problems occur immediately after changing to a new tire type or make, revert to the original tires to see whether an improvement can be noted. In some instances a change to what are, in fact, suitable lyres may give rise to handling deficiencies. In this case a thorough check should be made of all frame and suspension items which affect stability.
© April 2014