I have a 1987 GN with about 145k miles on it. The rear end is making a fairly loud whining noice on DECEL. When I am cruising or accelerating there is no noticeable noise. I've ran red line posi differential oil in the diff for many years so it's got me surprised to have rear end troubles.
Any input or ideas as to the cause or fix would be appreciated.
My 87' does the same thing, even with the GM diff. additive. My mechanic, who strictly works on TRs' says it is absolutely nothing to worry about. I have 129k on my car and I have had no problems so far. I have a question for you...When you are cruising at 65-70 mph, does the car vibrate? To the point where the headlights in the rear view look like rings? I have also been told that this is not a problem, not just by my mech. but also by other regal enthusiasts. Although no one seems to think this is a problem, I still feel as if it will create a problem later. So I guess I don't have an answer to your problem, I just have the same problem.
Usually the whining is the age on the posi units themselves. My friend had this problem and came to the result that it was a slight warp in one bearing that made the noise. Not something that would kill the rear but enough to make a little racket. As Far as what i like to refer to as the Chevy Shimmy which it seem all GM's develop after about 75,000 miles it's just the way the front suspension wears. You get a slight shake that disappears after you cross the 72 mph threshhold because there is more air on the nose to push down and take the shake out. Not a real problem just typical GM.