Sure Grip or not

[Joseph24251_200]

Ok a few years back i purchased a 8 3/4 from a salvage yard it has a 741 center and it came out of about a 73 or 74 Dart. I got it for $275 but heres the thing the other day i backed up about 15ft on the street just to get straight and when i gunned it both wheels spun, one a lil less then the other. When i got this rear i was thinkin it was an open carrier, what i wanna know is could this be a worn out sure grip cluthch type and how can i tell? Also shouldn't a sure grip pull both tires at all times or do u have to back up 15ft just to get it to lock?

 

[OldVart]

About the only way to tell for sure is to pull the center section and have a look at the unit. Sometimes, even without a sure grip, if the car is nice and level, on a flat surface, you can get both wheels to spin a little.
Also, check the bolts that hold in the center section and see if there's any type of a small metal tag attached to one of them. That may give you a little more insight into what you actually have for gears, etc.

 

[Joseph24251_200]

ok it actually happen more then once and the gears are either a 3.23 or a high 2 something. I check the gear ratio a whille back by jackin up both rear wheels and countin the number of times the wheel rotated and the yoke. i actaully checked twice one only rotated backwards the other time both wheels rotated the same direction. I'm askin because i want both wheels to pull u might know that. But i was about to buy a locker but if it has a sure grip i don't need a locker i just need a rebuild kit right. I guess i'll just pull it first and find out. I have to many projects!!!!!!

 

[ramcharger]

Jack the car up and spin one wheel. If both wheels spin the same direction, you have a sure-grip or a locker. If they spin opposite diections, it an open rear end.

An open rear can spin both tires if the traction (or lack of) is exactly the same on both tires.

 

[charger70]

I believe backing up is an old urban legend. at least for Mopar. I heard that too when I was a teen in the early 70s.
Another way to check,
With only one rear wheel off the ground and trans in Nuetral. If you can spin the wheel its open, cant spin , sure grip.
With both rear off ground and trans in park (or in gear for manual) if you can't spin, sure grip, if you can spin the other one better be going the other direction or you likely have a broke axle.