Originally Posted by
OZMDD
I'd first try to establish whether or not it is caused by the vehicle moving or is isolated to the drivetrain. Put the car on a lift/jack stands and see if you can replicate it without actually going anywhere. Then I'd start looking for the source (need two people for this.) Might be early stages of a dry or dying throwout bearing.
FYI - WD40 isn't really a lube, and can actually loosen/wash out the real grease in your u-joint bearing caps. It has some lubricating properties, but is really intended to free stuck/rusty parts and dry wet parts.