There are, of course, many other causes which contribute to the little noises which accompany the car along the road, but the novice will find here the most common ones, and by a process of elimination may arrive at his particular bane; to find it naturally suggests the cure. Therefore, stop that knocking.
CHAPTER XL
CHASSIS KNOCKS
Does your car chatter? Does it talk to you and protest against running over holes and bumps in the road? If it does, it is a sign to which you should pay attention, a hint that you should do away with the knocks and clicks and chattering which annoy you and everybody else within hearing as you run along. That is, if you can find them, for there are some noises so obscure as to defy detection even by the expert.
Such was the car which developed a sharp click whenever it was started forward or backward. It ran quite a long time before it was possible to discover just what and where it was. It was somewhere in the back, but so hidden as to defy detection. The rear axle was of the floating type, the construction in which the driving shaft is connected to the hub of the wheel by a number of flutings on the shaft, into which corresponding projections of the flange fitted. These had become worn and allowed sufficient play to cause a noise.
By walking alongside of the rear wheel while the car was being started and stopped, it was decided that the sound came from the hub of the wheel. The hub cap was removed and by placing the finger on the hub flange and end of shaft at the same time the play was detected by the sense of feeling, though it was hardly visible to the eye. The trouble was overcome by having the shaft welded to the flange.
A few days later the owner happened to be at the agency and told what he had found.
“So glad you came,” was the response, “for we have been looking for the same kind of a click a long time ourselves and the service-station mechanics have not been able to locate it. They thought it was in the brake, but upon examination could see no reason for a click.”
There have been cases where the wheel was keyed on, and where the keys had acquired sufficient play to cause a continuous knocking, especially when the machine was being driven at low speed. This sort of knocking is more likely to occur with the four-cylinder, slow-speed engine than with the high-speed, many-cylindered type.
A mysterious knock may sometimes be traced to the torque rod, when it becomes loose at the forward end, or to worn torque-tube bearings, and in some cases the bolts fastening the torque rods to the rear axle become loosened, or worn, causing a knock, especially when going over bumps or dropping into holes.