How can I tell if my car has a posi/ LSD differential.?


Asked by Nov 30, 2009 at 11:46 PM about the Pontiac Firebird

Question type: General

I jacked up the car so  both rear wheels were in the air and spun one, the other spun in the opposite direction. ?  

4 Answers


Typically this means that you either you have an open diff or very worn limited slip unit. Try turning one side while someone holds the other side. If your side still spins then it's open.


I'll try, thanks.


Ok so I got the chance to test this out. I jacked up one wheel, put the car in drive and tried to spin the wheel. It was able to spin forward easily. Then I spun it in reverse and it wasn't able to spin as easily, so according to you I do not have a posi diff. However, when I accelerate quickly and peel out, I leave two tire marks on the pavement, indicating that they both spun. I am real confused. What ya think man?


Do a burnout and turn the wheel some as your roll forward. You should get two equal length marks. One will be shorter if one stops spinning indicating an open diff or slipping cltuches. It might be easier to pull off the cover and look at the gear set .

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