This is somewhat interesting. I can drive the Formula without any noises coming from the rear for about 25 miles. After everything is nice and warm......
Slow turns, forward and reverse, brakes on or off doesn't matter. I hear this clunk/knock noise coming from the rear. I'm hoping you guys can help me out. Whether it's diff or spiders why would it make no noise until it's warm?

I don't even have a whine just the hot clunk.

 

i'd look at u joiunts and torque arm followed by any other bushing in the rear

 

I'll look at that stuff but in regards to u-joints, isn't that a whine that changes pitch with drivetrain rotational speed? This noise only happens on 1-4 mph turns. They also have to be sharp turns.

 

did you change the diff fluid yet and add some fresh posi additive?

 

is this a 9 bolt rearend? what shape is the posi in, if u jack it up and leave the car in park (auto) or 1st gear (5spd) and try and move the rear tires, see how much effort it takes to move the tires in opposite directions.

 

I changed the diff fluid about a month ago. I used Amsoil which should include the posi additive.
It is a 10 bolt. It is very difficult to turn the tires in opposite directions while it's jacked up.
I'm thinking the posi is fine but maybe the spiders are going. Saturday I'll be checking the stuff ede posted about. Any more suggestions on what to check for Saturday?

 

My u-joints and bushings are all fine. Nothing moves. The rear has develped a quiet whine at slow sharp turning speeds. I'm wondering if a bearing is checking out.

 

Still working on this problem. I have it up in the air for now. How would I go about checking the side gear bore? According to my Helm's the side gear bore, if oversizing, could cause this problem. I've eliminated all other possibilities that I know of except this and the posi itself.

U-Joints are not leaking and have no slop
All bushings are acceptable
No metal particles in diff so bearings and gears are good
Torque arm is solid

More help?
:hail:

 

time for a new rear end... you blew out the spider gears... LoL my friend just blow his out in his K-5 blazer did the same thing that your talkign about. LOL i'm on this web site right now looking for the link to that one 10 bolt web site that everyone raves about.

good luck...... time for a better POSI unit

 

That's exactly what I don't understand. Every single gear in there including the spiders are in perfect shape. The wear pattern is even perfect.
I'm going to try different gear lube and see what happens. Who knows, maybe this posi is extremely sensitive. Maybe also the Amsoil series 2000 gear lube I put in there was short in the posi additive department.