My dad's 02 suburban is makin some rear end bearing whine. It does it worst when the driveline is loaded. When you unload the rear, it still whines but is much quieter. If I remember correctly if you hear whine under load it means the pinion bearing is the culprit. Is this correct? Any other ideas out there?

 

Has any work ever been done to his rear axle?
If so maybe the lash between the gears was inproperly set.

 

no, everything on the truck is bone stock.

 

I'm guessing it a G80 rear axle not an open diff?
How many miles on it to date?

 

I'm not 100% sure, but I think it's a G80 because he has the factory installed tow package. About 65000 miles. I don't think it would be G80 unit failure because he drives this thing like a grandpa.

 

Has he ever had the fluid in the rear end changed? If not, its definitely overdue. I'd start there first. Its a fairly cheap fix, if thats all it is. I just did mine this past weekend, took me about 30-45 minutes and about 25 bucks for the fluid.

 

I already told him to do that and see if it helps any. Supposedly the service interval is 100,000 miles on the synthetic diff fluid. I changed mine every 25 cause I'm **** like that.

 

I would have him change it even though it says teh interval is 100k miles

 

I have been told by many here not to use synthetic oil in the diff.
I used dino oil when I did my eaton install and have had zero problems.
Don't for get the friction modifier!! 4oz bottle.

 

Depends which rear you have...the G80 calls for 75w-90 synthetic w/ no additive, while most aftermarket lsd's need dino w/ a friction modifier