I don't know where to post this but would someone explain to me why with a positrack rear end if you spin one tire the other goes in the opposite direction?

 

actually the myth for posi-traction is if you spin one tire the other will spin the same way.

posi-traction is just GMs name for a limited slip.

here: http://auto.howstuffworks.com/differential.htm

 

That is with a non-posi rear end.

If you don't have a posi rear end (open differential) when you have the car in the air (jacked up) and the wheels are off the ground, when you spin one wheel, the other will go in the opposite direction.

 

yet.... the 02 trans am i was swapping rears on 2 weekends ago did the same thing.. they spun the oppisiate way.

but.... it has a posi.

the 4thgen SS i was messing with the same weekend did the same thing... they spun the opposite direction.


but..... it has a posi.




the only SURE way to know is to look.
and you probly need to change the gear oil anyway, so just pull it and look.

the spinning the tire method is pure bullsh!t. only SOME limited slip diffs spin the same way, and of thoes, some spin the oppsite when they're worn.

 

The newer ones (LS1 cars) don't have clutches; they accomplish the same end result in a different way. Therefore the "test" doesn't work on them.

You can't go by all of those "tests" you hear about; the only sure way to know what you've got, is to take off the cover and look.

 

bingo.

athough my car doesnt pass the test either..... then again, i dont have a stock posi unit in mine.. its also clutchless.

 

My 9" Trac loc will spin the wheels in opposite directions, yet it will lay two equal length strips of rubber on the ground. Point is there are many different types/designs of limited slip differentials out there. They all accomplish the same thing by different methods.

 

While all that info's great I kinda meant how do both whells spin the same direction while in drive but when the back of the car is in the air if you spin one wheel the other goes in the opposite direction?

 

from the link i posted:
http://auto.howstuffworks.com/differential3.htm



look at the animation. if you think about it carefully, you'll be able to visulize how everything is moving.