I have been having problems with the rear diff in my S. It makes a high pitched hum sound when I am decelerating, out of gear, and foot off the gas. I went underneath and jack it up, and noticed that I can wiggle the axle input shafts and the driveshaft input shaft, which all go into the diff. housing. Is this normal? It is supercharged and I heard the bearings wear out faster in the charged ones. I just adjusted the backlash also, which I thought was the problem(it wasn't)
I think all my bearings may be shot, would this account for the hum/whineing noise? Also does anyone know how much the parts cost for a diff rebuild?(bearings, seals,etc>)

 

WHEN I CRASHED MY S2000 I SCREWED UP MY REAR DIFF. AND IT MADE THAT NOISE TOO. MY INSURANCE COVERED MY ACCIDENT AND THE BODY SHOP SAID THAT I HAD TO REPLACE THIS AND THAT AND ONE OF THE PARTS THAT NEED REPLACING WAS THE REAR DIFF. I CAN'T REMEMBER HOW MUCH THE REAR DIFF. COSTS BUT MY TOTAL FIX ON MY CAR WAS $10,000.00. I HOPE THAT HELPS YOU A LITTLE. ALSO THERE IS A LOT OF THINGS YOU ARE SUPPOSED TO DO WHEN YOU SUPERCHARGE YOU CAR LIKE REBUILD THE TRANY, AND THE COOLING SYSTEM AND MOST IMPORTANT THE SUSPENSION.

 

Anyway... When you checked your backlash, did you loosen the locknut that holds the companion flange onto the pinion? It sounds like it is too loose (ie. too little preload on the pinion bearings).