i have a 9 bolt posi rear end on my 89' formula 350, when i 1st bought the car a year ago, the posi didnt work. but after driving a little while consistantly, the posi started to work fine. im in on spring break home from school now, i fired up my car and did a burnout, but there was only ONE tire mark!!! the car has been in storage since december, and hasent been driven really at all since july. if the car has been sitting alot could that effect my posi? i think it wasnt working when i bought it becuse the previous owner wasnt driving it at all. in this case, when i start driving it alot in may, will my posi start working again? i REALLY dont want to get a new one

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89' Firebird Formula WS6 L98, MSD 6AL MSD Blaster, Hypertech chip, K/N filter cone,flowmaster 80 series, hypertech air foil, koni shocks, edelbrock trailing arms

 

I don't think a sitting posi will get any better. Keep in mind that a worn out posi might leave 2 tire marks sometimes. Before my powertrax, I left 2 tire marks about a third the time(open rear end). If traction is equal on both wheels, any differential will spin both tires. That being said, don't assume your posi is working like it should if both tires spin.

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82 camaro--original steering wheel, brake/gas pedals, seats--everything else modified
82camaro

 

you should also know that limited slip still is not a true posi even in its best condition. it only has springs pushing against the clutches so if one tire is free and the other is solid it sure wont take much to over come the springs holding power