Diff problem

[jondee86]

Anything that changes the point of contact between crown wheel and pinion
could potentially lead to a whine from the diff. But if the mechanic replaced
the pinion bearings, I should think that he set the pre-load correctly.

Last time I researched this question (as it comes up regularly) I believe that
I read that the noise is a resonant frequency generated by the teeth of the
pinion striking (contacting) the teeth of the crown wheel. Typically the
noise will be speed related, rising to a maximum at a certain speed, and then
fading away as the speed increases.

In effect, the crown wheel is ringing like a bell under the impact of the
pinion teeth. Settin the pinion depth incorrectly is said to be one possible
cause (contact patch not in the centre of the tooth face).

Cheers... jondee86