One-piece driveshaft

[jondee86]

One of the difficulties is that the driveshaft tube itself is subject to a
sinusoidal movement relative to the position of the input and output
stubs. This occurs at a frequency twice that of the rotational frequency
of the input/output stubs.

It is almost inevitable, that this torsional vibration will (at certain speeds)
coincide with one of the system resonant frequencies. In the worst case,
the effect will be an annoying vibration that rises to a peak at a particular
road speed, and then fades as your speed increases i.e. you can "drive
through" the vibration.

Because it is a system resonance, it can and will be influenced by other
rotating components. Anything that rotates, from the engine fan to the
rear wheels, can change system resonance. Car manufacturers will go
to a lot of trouble to counteract system resonance, and it is rarely a
problem when cars leave the factory. However, once owners start
modifying the car, resonance problems (noise or vibration) can occur.

Cheers... jondee86