The driveshaft is an important part of modern engines. It takes the power from the engine itself and turns it into propulsion. Under normal working conditions, it's a silent part, so when it begins to vibrate, you can be sure that something's wrong with the engine. Knowing how to fix driveshaft vibration issues is an important part of engine maintenance.
An improperly balanced driveshaft doesn't sit correctly in its housing. This alters the angle at which the driveshaft connects with the double-cardian joint at the end, which affects whether it's held at a constant velocity or not. As a result, engines with a constant velocity joint on the driveshaft will vibrate when the engine is on.
Universal joints (also known as "U-joints") hold the driveshaft in place. When they get worn, begin to work loose or lose their lubrication, the driveshaft will begin to vibrate while the car is moving and the engine is running. This is easily remedied by adding more lubricant, tightening the U-joints or replacing them if they've worn out.
The yokes on the driveshaft should be in line with one another, even on a "multiphase" driveshaft. This allows the driveshaft to operate at peak efficiency and not fight itself during use, which causes vibration. The yokes should be in the same position on both ends of the driveshaft, which can be achieved by rephasing and realigning the shaft.
