when I take off hard my rear only locks up sometimes, seams like when I baby it it locks up more. going into 2nd it locks up a little more but not all the time.Does any one have any ideas why. I'm still trying to get the #s off the rear, but between undercoating & rust it's hard. ( it's a 12 bolt in a 69 z ) The track opened 2 weeks ago & I would like to make some runs in a week or two. My 18yr.old son wants to go and bring some friends from school & I doin't want to get beat by some riceburner in front of them. Thanks Bob

Got the right posi gear oil in it? not all limited slip oils work in a posi.

thanks for the help,I was out of town for a few days so I just got your info . I'll drain and refill the rear & see what happens. Thanks Bob

If it is a clutch type, either the clutches could be worn or your putting more power through the rear than the current set of springs can handle and may have to upgrade to thr 800 pound spring set.


Larger Dave

I'll drain and refill the rear
not all limited slip oils work in a posi.
We are in NZ...I went thru 3 diff types...then at wits end, called ito another diff shop who have me some of his stock out of a bulk drum..no labels...worked perfect ever since.
The problem now is The guy has retired and died...]
I THINK it was a Goodwrench??? oil?

Also there is an additive, I think about 8 ounces, but I can't remember the name of it.

Rob

Go to a GM dealer and get some Posi-Lube additive.

Kev

Go to a GM dealer and get some Posi-Lube additive.



I'm pretty sure this is a friction modifier, and would make this situation worse.

I'm pretty sure this is a friction modifier, and would make this situation worse.
Right, the posi additive is for "smooth operation"

Two years ago my sons 12 bolt in a 70 chevelle would make loud snapping noises when he drove around a corner, he had me listen outside the car, it sounding like something was binding up and then it would make a pretty loud noise, the guy in town that works on this kind of stuff said to put the positract lube, about eight ounces, it went away, but what he has is probably different.
just my .02 cents.

Rob