So I have made my prototype single link tire chain to get me rolling if I get stuck or need a bit of traction to make a snow and ice covered hill.

But I need to know if an older Astro van is single wheel or posi and if single which wheel it is? I also have an old Olds rwd car.

Is there a standard on GM rwd vehicles?

Thanks.

One wheel drive on GM's is pass. side rear.

AFAIK, with a conventional differential, either wheel will slip depending on which has the most traction. You cannot predict.

Raise both rear tires off the ground, engine off, transmission in neutral, parking brake off.
Rotate one rear tire by hand, if the other rear tire rotates in the same direction, it has a posi diff.
Be sure and use jack stands, and block front tires from moving.

On a non-posi rear axle the tire with the least resistance will spin, so either side could be a drive wheel.

GM started in 1984 a large black and white adhesive label in their cars and trucks called a SPID (Service Parts ID) with RPO (Regular Production Option) and interior and exterior paint colors. Earlier pickups and utility (Suburbans, Blazers, etc) had a blue and white label in the glove compartment, underhood or on a front wheel skirt a similar label. Letters and numbers, at the bottom of the label there will be codes like 8811U/8811L followed by BC/CC. Those are the exterior colors, "U" is upper body color,"L" is lower, BC/CC stands for "base coat/clear coat" paint type.

SPID's are usually in different locations dependent on vehicle line, in the trunk on the deck lid, if the spare tire is under the trunk mat it is sometimes stuck to the cover. Inside the floor console (if there is a removable compartment sometimes under that) or in the glove compartment and sometimes under the hood or on a fender skirt. If the SPID is not there you can take your 1990 and later VIN number into a GM dealer and they can reference that information (usually) in the Electronic Parts Catalog's data base.

Anyway, you are looking for the code "G80" on the SPID label, a non Positraction axle does not have any option attached to it. Also, many GM vehicles also had a small metal tag attached to a differential cover bolt stating "Use Limited Slip Lube Only"

If you can find the build/spec sheet look for a G80 code.

It will not be one wheel even if it is an open differential. Either could break loose and spin in that case.

Yep G80, it's a locking diff. not a limited slip

quote:

Originally posted by GaryBF:
AFAIK, with a conventional differential, either wheel will slip depending on which has the most traction. You cannot predict.

IOW, one chain is useless unless you are positive it's posi.

There’s a reason tire chains come in pairs.

Thanks guys the Astro is a 97 I think or close to it. The olds is a late 70's

If I cannot get traction with either rear wheel and I throw the chain on the passenger rear and I can get a bite it will be the wheel that drives, win?

The car that made these two equal length tire marks had positraction, can't make those marks without positraction, which was not available on the 1964 Buick Skylark
What is positraction?
It's a limited slip differential which distributes power equally to both the right and left tires. The '64 Skylark had a regular deferential, which anyone who's been stuck in the mud in Alabama knows, you step on the gas, one tire spins, the other tire does nothing.

quote:

Originally posted by old rugged cross:
Thanks guys the Astro is a 97 I think or close to it. The olds is a late 70's

If I cannot get traction with either rear wheel and I throw the chain on the passenger rear and I can get a bite it will be the wheel that drives, win?

An open differential will divert all power to the tire without traction, so you will still be stuck. Applying the parking brake can help, but if you're really stuck you need traction devices for both wheels.

quote:

If I cannot get traction with either rear wheel and I throw the chain on the passenger rear and I can get a bite it will be the wheel that drives, win?

What folks are saying is in a car without posi, the drive will go to the single wheel with the LEAST amount of traction. So in your example, no.

Heres a video of 10 snow/traction devices you can pop on or off your vehicle rather quickly, the first one, the AutoSock requires these things called Tyres, and you need to be able to move your vehicle in Metre's

There are some clever ideas presented.




Link to original video: https://www.youtube.com/watch?v=chrLCKzAVVg

quote:

Originally posted by RichardC:
The car that made these two equal length tire marks had positraction, can't make those marks without positraction, which was not available on the 1964 Buick Skylark
What is positraction?
It's a limited slip differential which distributes power equally to both the right and left tires. The '64 Skylark had a regular deferential, which anyone who's been stuck in the mud in Alabama knows, you step on the gas, one tire spins, the other tire does nothing.

Some have a limited slip differential. Those are better than the unlimited slip differential.

Positraction was a copyrighted name by Chevrolet, Pontiac called theirs Saf-T-Trak, Ford Equa-lock and Chrysler Sure-Grip.

There are others, I've forgotten a bunch of useless facts since I'm out of the business now.

"Positraction," or "posi" for short, has become sort of a genericized trademark for a limited slip differential. I'd like to call them "LSD" but I keep getting funny looks.

a single tire chain is useless. Even on a limited slip differential if the amount of difference in traction is great. note the limited part. its a clutch pack not a locker.
Go for a pair or go home.
I love the my cousin vinny quote. one of my favorite movies.