VY Mechanical Noise?

[Seth_23]

So this is going to be hard to explain, but when I drive my car at certain speeds, it makes a strange pulsating mechanical noise when I sit at certain speeds, usually 100Ks exactly, going slightly faster or slower, the sound goes away.

Its very constant/rhythmic like "vrrr, vrrr, vrrr, vrrr". I'm not too sure if its coming from engine or g/box. Any help would be much appreciated!

[Sean880]

Is the gear box manual or auto?
Are you sure the noise originates from the engine or gearbox and not elsewhere up front? (Last time I heard a noise as you describe (not in a commodore) it was present most of the time when you applied the throttle and sounded like an auto gearbox problem, especially when under load. But the owner claimed it was something else).

As you say the noise starts in your car at about 100 kms are you sure it is not front wheel/hub/bearing related? Just a thought.