Help with Differential noise maybe?
 

When I make left turns and some times right turns from a stop I get a loud moaning sound coming from the rear end area of the car. Mostly the noise happens on left turns. The moaning noise goes away when I straighten the car up. There is no sliding feel to the car in the turn only the noise! I have had the differential rebuilt but probably have less than 500 miles on the differential. The car is a 64 with a stock 327 and a 4 speed. This morning I drove it over to a friends house who has a pit in his garage and we could not find any marks that indicated that something rubbing against the floor or another part. Everything seemed tight without any side play or movement.
I know that without being able to hear the noise this question is going to be hard to answer but I am hopping that someone here has had the same noise or close and can possible tell what their fix was or where is is coming from. Could the clutches be failing in the differential? I have also sprayed silicon on all the rubber bushings that come in contact with metal thinking the noise might be coming from them. I did not grease the big donuts the are between the cross member that holds the differential and bolts to the frame, could the noise be coming from them? Thanks for any suggestions.

Rear
 

If the car has a posi unit, the noise you may be hearing are the clutches sticking in the rear. This is a fairly common problem. Get the car on a lift or high on a set of jack stands, remove the fill plug and suck out the fluid .Harbor Freight sells an inexpensive hand crank liquid transfer tool you can use to empty and fill the rear. Replace with two bottles of posi additive from GM and two bottles of gear oil. You can get both at your GM dealer or from NAPA. The NAPA additive is sold as a posi additive or limited slip differential additive. Fill with gear oil until it runs out. Install the fill plug. Drive the car to an empty parking lot and drive the car in tight figure eights in forward and reverse for a few minutes. Check for leaks and call it a day. Jerry

I agree with Tampa Jerry, but for a second thought, what is the history of your spindle bearings? Have they ever been rebuilt? :cheers: Dennis

Not sure what the spindle bearings are? He also rebuilt the trailing arms. What brand, and weight gear oil should I use? Thanks for the responses.

Sounds like posi chatter. Did you call your builder to speak with him? Question would be what type of clutches were used and how were they setup?
If there was a drain plug installed then changing out the oil is easy. You should have been instructed to break in the rebuilt diff as well and change the oil at 500 miles, did you get that info?

You should use 2 bottles of Gm additive and a non synthetic gear oil, 90 wt or 85-140 is what I use. I change it out at 8-10k miles.

Thank you. I picked up 2 bottles of additives today and will change the oil in the differential tomorrow and hope for the best! Let you all know what transpires.