Moroso Climbing Gear Lube...?

[HammerDown]

A knowledgeable friend suggested I try the above gear lube in my 81. It's always had the clunking sound when coming to a stop. He said "it will cure the clunk" When I change out the fluid and add two bottles of the GM additive it goes away for a time but always returns.
Soooo any feedback about the Moroso stuff?

 

[Hib Halverson]

There is no such thing as a lubricant which will cure a "clunk" coming from your rear axle.

In fact, there's a chance that the "clunk" may not be related to the rear end at all.

I would get the car up on jack stands or a lift and carefully inspect the rear suspension and the rear axle for problems.

If you determine the clunk is coming from within the rear axle assy., it probably needs to be overhauled.

 

[HammerDown]

There is no such thing as a lubricant which will cure a "clunk" coming from your rear axle.

In fact, there's a chance that the "clunk" may not be related to the rear end at all.

I would get the car up on jack stands or a lift and carefully inspect the rear suspension and the rear axle for problems.

If you determine the clunk is coming from within the rear axle assy., it probably needs to be overhauled.

"There is no such thing as a lubricant which will cure a "clunk" coming from your rear axle."
...Then why does it not clunk when I change out the oil and refill with clean oil w/addative?

"In fact, there's a chance that the "clunk" may not be related to the rear end at all. "
...for sure it's the the rear my guess the clutches are sticking

"If you determine the clunk is coming from within the rear axle assy., it probably needs to be overhauled"
...it's been doing this for some 100,000 miles also if I do some figure 8's in a parking lot it clears it up for a short time.
Thanks for the feedback

Edit question...what type of limited slip is in our Vette's? Is it a plate, gear or cone type limited slip?

 

[JohnZ]

The original Posi unit is an Eaton plate-clutch type. If the additive cures the "clunk" (or chatter) temporarily and the symptom comes back, your Posi needs an overhaul, and changing to the Moroso race-track lube isn't going to help you at all. Have the Posi unit professionally overhauled and use GM Diff Lube and two bottles of GM Posi additive when it goes back in and you won't have to touch it again. Fixes for Posi chatter that keeps coming back don't come in a bottle.