I have been fighting a diff. problem here lately. The car is an FD. Had the stock torsen in it and started to get a nasty whine. Tore it down to find some chipped teeth and side play/ Went ahead w/ a S4 turbo II clutch style internals and the previous FD matching final drive. Put it back together and it had a bad whine. The pattern was set correctly so we figured it was the gear set just worn down. Went w/ a new 4.30 fianl drive from mazda. Pattterned the gears shimmed it to within spec (perfect actually) and buttoned it up. Went for a drive and still have the bad whine. As soon as the tires rotate the whine is there. On or off load ( in gear or coasting). Any ideas? Is the pattern off? Dont know what else. Thanks G

 

The noise is there when the clutch is engaged. When you depress the clutch pedal it is not. Obviously a load noise transfer. I do have solid rubber diff. mounts. It is way to much noise for that. Bad wheel bearing noise ?

 

G

FYI Many of the diff threads for the FDs are in the 3rd gen section.

I don't have mod privileges in this forum or I'd move it.

 

does the noise go away as soon as you push the pedal, or does it wind down and stop after pushing the pedal all the way in?
does it do it while sitting still or only moving?

my first guess is your throwout bearing is toast

 

Bad rear hub bearings?

 

Yes. it goes away only when the pedal depressed. A throw out would cause noise in the diff.?

 

Possible. This noise was not there before we tore it down. It is different then the previous bad diff. noise.

 

not in the diff, but its really hard to pinpoint a noise from inside the car. if it does it while sitting still, thats a dead giveaway (since the diff isnt doing anything).
just trying to help narrow it down