Input from the techs on what might have happened with my Diff.

[G-Tech]

i have a R200 with 3:54 gears and Quaife internals. Its in a 280zx with a LS (400whp) motor. The diff has been awesome to me for the last 12years, ever since the 1st v8 motor. I had a professional install it originally 12years ago and did nothing but put a 300zxt diff cover on it a few years ago so obviously i changed the fluid then. It has always had a slight whine to it under light throttle when on the highway. if i let off the gas it goes away, if i accelerate more it goes away. It was explained to me that because it is a gear driven unit that it will have that whine. No big deal.

Anyway, after my most recent trip to the drag strip(which i do a couple times a year). The whine has now gotten a little louder. its the same whine, the same characteristics just all of a sudden, now its lil a louder. And yes it has fluid, it was the 1st thing i checked

What does anyone think might have happened? Is it about to go or maybe it needs to be re-adjusted and/or re-shimmed? It makes no other noise or clunk.  

Thank you for any thoughts you might share

 

[NewZed]

12 years behind a lot of torque, with yearly abuse, is a pretty good run.  Bearings do wear.  Maybe it just needs a refresh.  Carrier bearings are pretty easy. 

 

An easy way to see if they're worn is if the carrier falls right out when you take the caps off.  It's funny how much attention is paid to getting perfect preload but after thousands of miles the preload disappears as the bearings wear.  And as the bearings wear it should allow the ring gear to move away from the pinion gear which might cause noise.

 

Just a guess.  I haven't worked on an R200 but I have been deep in to a Ford diff.  They're all similar.

[G-Tech]

Thank u Newzed. That's a good start for me to look at. That diff owes me nothing so if I had to replace it, I'm good with that but of coarse I'd rather a different alternative.  A friend of mine also suggested the same thing.