Just Took My 89 Bird out for the the first drive today. I'm trying to find out what gears and if it is limited slip my rearend has. It layed good doubles. It appears to be limited slip. Cause one spun before the other caught. It Is a 2.8 Bird converted to 305 with 10 bolt. Is there a site like mortec to tell me what the numbers mean. Will the numbers really tell me what gears i have. My dad is a old school auto tech and he said to jack it up and count something or spin the tires by hand . Thank guys

 

pull the diff cover to know for sure what it is, or if you dont believe the gears or anything have ever been swapped in the axle housing then get the stamping code off the right axle tube it is stamped into the tube housing about 4" away from the edge of the diff housing where the axle tube slides in

it will be three letter/numbers code

call your local chevy parts counter and have them decode the code for your year make and model

and hope that it is the original axle housing to the car and has never has a ratio/carrier swap

pulling the diff cover is stil the best betotherwise you weill never know for sure
limited slip/posi sends power to the tire with the most traction

it is not like a locker

good luck

 

For a quick check for posi, jack up the rear end so both wheels are in the air. Turn one tire and look at the other one. If the other tire spins in the same direction, it's posi. If it spins in the oposite direction, it's just a regular open diff.

 

Old wives tale. This doesn't work for torsional type posi units. - If you want to know, pull the cover. You can almost bet the fluid needs changing anyhow.

 

As soon as i get home in 2 days I'll ****** the cover off. so that is a old wives tales about spining one and the other going in the other direction. Learn something new all the time on here.

 

The spin one tire thing works for most standard plate type posi units, but not for torsionals or some cone type units.

 

I found that with the torsionals or some cone type posi units, if you have both tires jacked up in the air and slowly rotate one tire, the other will spin in opposite direction. If you spin one tire really hard and fast the posi cluch will engage and the other tire will now spin in the same direction. But you will feel a lot more resistance.

 

Sorry, my bad, I'm old school and not up on the latest diff. components. I could find nothing on the web about torsion differentials, but there is a lot of info on the Zexel Torsen diffs in f-body cars. If thats what you have it should be bullet proof. Torsen diffs are what they put in the aircraft tugs for towing airliners around the airport. I knew Mazda used them but had no idea GM was using a form of them. That's pretty cool.

 

Pulled cover and got some pics and a few numbers tried to find a site with listings to no avail. What Numbers do I need? Ring and Pinion #'s, or carrier #

 

TTT