This is perfectly normal.:
http://en.wikipedia.org/wiki/Universal_joint
The reason why this happens is the angle on the driveshaft.
On extreme angles there will occur an acceleration and braking of the wheel side, which is then heard as the chatter.
You can actually see the acceleration if you turn the driveshaft at an angle by hand.
he only possibility to remove this is using a second link in which the acceleration are cancelling each other out:U4173 True C.V. Driveshaft; Front - CAT
And C.V.D shafts aren`t constant velocity!
Cruise