My posi works sometimes (too slabs if Im goin straight) but not when im turning slightly to one side. It seems like maybe the posi is getting a little worn so I was wondering if it would help if I threw in another bottle of GM friction additive. I thought I read that this helps. Anybody?

 

The 9-bolt is a cone-type posi. The friction modifier is designed for clutch-type posi's. Note that according to a GM TSB, the 9-bolts are not supposed to get the posi additive.

Beware - this is a controversial issue (for some inexplicable reason) on this website.

Do a search - a while back I documented all of GM's statements regarding the 9-bolts and posi additives.

If it's any help - my rear end gear oil was replaced 10,000 miles ago and the posi additive was put in. The posi stopped completely working. I drained it and put in Red Line Gear Oil for non-posi rears and my posi works better now. Coincidence? Hard to say. Just one man's experience.

 

Really, thats news to me. No additive..... interesting. Ill do a search and check it out. Thanks

 

Let me know what you find. I have "mystery 9 bolt" seems to be a 3.08 posi, but only posi like yours. maybe thats how they are made?

 

No that behavior is not normal. The cones are starting to wear out. An alternative to replacing the posi unit itself is to shim the posi cones. Another guy at this site (Larry Burd) has done this.

 

some 9 bolts "chatter " going slow with a small amout of lock applied to front wheels IF your car does that ad the aditive and it will stop !