suregrip question

[challenger71]

when you spin a rear tire on a suregrip if the tire spins and the otehr does not, does that mean it is a limited slip posi. I believe that if you spin a rear tire and the other tire spins the opposite direct, it is an open rear? Am I right or confused?

[70_challenger]

You're partially correct...
If you spin one rear wheel, and the other rear wheel spins in the same direction, it is a positraction diff.  (Of course, those are called 'Suregrip' by us Mopar guys!) 

As you said, if you spin one wheel and the other wheel spins in the opposite direction, it is an open diff.

-Tom

[challenger71]

I have an issue then, cause when I spin one tire the other does not move. Any ideas?

[brads70]

I have an issue then, cause when I spin one tire the other does not move. Any ideas?

Both tires are off the ground right? If so maybe a brake is holding it from spinning. It's normal for one wheel to not spin in an open diff when you turn the other.

[the_engineers]

When the tires are off the ground, what was said is correct. With wheels down, an open diff only spins one wheel, a SG spins both.

[70_challenger]

Right.  I was assuming that your wheels are off the ground when doing this test.  If they ARE off the ground, and one is stationary, then I would suspect that it is an open diff, and the brake is probably holding it still (as Brad stated)

-Tom

[challenger71]

Ok, so then what does it mean when the wheels are off the ground and I spin a tire and the other tire spins the opposite direction. I thought that meant it was an open diff.  the brakes are not locked up because they both spin very easy. I have never had it when one tire spins and the other does not. I've always had it that both tires spun the same direction or they spun the opposite.

[Chryco Psycho]

opposite is an open diff

[UKcuda]

Put it in park ?

[Bullitt-]

  I Don't Know......But I wonder if it's a sure-grip that is worn out....Is that a possibility?

[Supercuda]

Possible, but with both wheels off the ground it should still be able to spin them both in the same direction. A VERY wiped-out SG diff will only react like an open one, but that would be shortly before it tried to leave the housing. Cone-clutch styles will do this pretty often, but only on a high-mileage unit or one that has been badly abused. The plate-clutch style is a little easier to tell if it is SG when wiped out, because the clutches will generally hold under a no-load test, but spin free under any real torque. Best bet is to remove the pig and see, if you have doubts.

[challenger71]

That is what I will be doing next week, tearing it out. I know on my 71 when I spun a tire off the ground the other tire spun the opposite, but on this 73 when you spin one side the other does not move. So far that only thing going for me is that it has a 489 case. I won't sell it to someone until I know for sure if there is anything wrong.

[Cooter]

If you are able to move one wheel independently of the other, It's an "open rear. What I think is happening here is that if you will look at the driveshaft, I think you'll see it is moving.. Instead of the other wheel in the opposite direction. An open rear will either move the other whell in the opposite direction , OR the driveshaft if in Neutral...Like mentioned, put the car in park and the rear is forced to walk around itself sending the other wheel moving in the opposite direction...

[dodj]

Put it in park ?

If you do as UK says, I'll bet it spins in the opposite direction.

[challenger71]

Unfortunately, I can't put the car in park cause it has no drivetrain in it.