I need some info on the posi unit in my 88 IROC. When I jump off the line, generally spinning, the rear end will posi about 15-20 feet then turn into a one wheel wonder. I am not familair with how the posi works, and would like to tear into it and fix it. I would like to know what I will need. This is extremely hard on the rear end when it does this and needs to be fixed. I have the borg warner nine bolt rear end.

 

The nine bolt is a cone style posi. If you look in the tech articles section on this site you will find one on shimming the posi which will cause it to hold tighter. You can do it to the point that it will not really slip at all.

Thanks

Ben

 

Thank you

 

If it's too far gone for shimming, I sell brand new series 3 posi carriers for 9 bolts. Also gear ratios to 4.10. All the info is on my page.

Miles

 

Have you treid changing the gear oil and adding some new posi additive?

Just a suggestion

 

I have the same problem and I've just been through this. The Borg Warner should NOT have posi additive in it (There are GM TSB's on this). The posi additive has a friction modifier that you want for your 10-bolt, but not your 9-bolt. I have some GL-5 Red Line Oil on order (should come via UPS today) that does NOT have the friction modifier. According to Red Line (who I contacted myself), the oil that I ordered should also help the posi action to occur more, which sounds like what you are looking for. If you are interested in this, I can post the web page that I ordered it from...