驱动轴断掉是非常危险的，我个人的主张是遵循古人的智慧，防患于未然。车轴断之前很长时间就应该有一些征兆，一定不能忽视。
southmountainer 网友问， 能讲讲有什么样的征兆？ 为什么有这些征兆吗？
先声明，坛里除了两位版主，还有许多高手，都有专业级别的水平，我自认为也就是业余小打小闹，连正时皮带都不敢自己换。所以问我问题，得到的答案很可能不正确或不全面，先交代清楚了，我下边好吹 ：－）
其实自己也吹不出什么来，伟大的股沟是咱的坚强后盾，我就股沟： Symptoms of Drive Shaft Problems，找来几个供大家参考，欢迎补充。
A vehicle's drive shaft--the rotating object located between the differentials and gear box--helps it switch from idle to drive; without it, a vehicle would never move. Usually, a drive shaft does not fail instantaneously, and deterioration happens over time. Accordingly, if drive shaft problems are recognized early, you can avoid costly repairs. There are various symptoms that indicate if your vehicle's drive shaft is faulty.
Vibration
A damaged drive shaft can cause the vehicle to vibrate. The entire vehicle or parts of it--especially the floorboards--may shake and tremble, and the vibration will often intensify and worsen at increased speed. Severe vibrations can also indicate a bad tire; however, vibrations from tire problems usually happen during acceleration, whereas drive shaft problems cause vibration when the vehicle is moving or stationary.
Sounds
A vehicle may emit noises if the drive shaft is bad. You may hear a low squeaking sound that intensifies with increases in speed. The sound may completely disappear when traveling at higher speeds and reappear as the vehicle decelerates. This is often the result of a severely damaged U-joint, a part connected to the drive shaft.
Turning Issues
A drive shaft problem can prevent your vehicle's wheels form turning properly. You may notice that the wheels hesitate when you turn a corner. You may feel resistance from the tires when making sharp turns or U-turns. You might also experience parking problems while trying to maneuver the wheels to turn into tight spaces.
Universal Joint Movement
A U-joint, or universal joint, that moves too much or does not rotate at all can indicate a drive shaft problem. To inspect the U-joint, set the parking brake and shift the vehicle into neutral. Move the yokes of the U-joint back and forth to check for flexibility. If there is excess movement in any direction, the U-joint is unstable and could negatively affect the drive shaft. Also, visible rust on the bearing cap seals surrounding the U-joint can indicate a drive shaft problem.
总之，在没有一点征兆的前提下，驱动轴突然断掉的情况，我不敢说没有，但可以说可能性很小，接近于零。希望大家不做车盲，平时好好学习，认真维护保养自己的汽车，才能极大限度地保证行车安全，避免车毁人亡。
