I am looking at adding a posi to my 84 'marro, actually I'm looking at a 4th gen rear with the posi. My only question before I go about looking for the new rear is will the posi unit make for an undrivable car in the rain/snow. I have heard stories from people who say that their truck/car consistently swings the rear end out on them in bad weather, but I really cannot see that happening if you respect the vehicle and know how to drive what you have.

The marro will never see the snow, but I am going to take to my astro later on, when I make some progress with the marro. I have an lsx swap in mind, probably a 5.3, I don't need the power of a 6.0 in the van. I like the sound of being able to put the power to the ground with both wheels, but only if I can do it in all weather conditions

I have heard the same thing as you, that a posi is unstable on ice, however my winter truck is a 1987 Dodge Ramcharger 4x4, It has Chrysler diff in the rear with thier version of posi-traction. The unit is so stiff that it pops going around tight corners on dry pavement. The front diff is Dana 44 with a manual locker. The front diff so stiff, that I actually broke a driveshaft turning tight on a hard clay surface with a heavy trailer behind. We live just outside of the Great Smoky Mountains National Park and I work as a RN on the Indian Reservation. Snow and ice are not considered an excusable absence from work, so the old Dodge sees it's fair share of ice, and some snow. I don't know if the weight of the truck has anything to do with it, but one has to work real hard to make it loose traction. We have seen it drag one wheel turning in snow in the parking lot, but the rear has never fishtailed on the highway. At one time, I was thinking about putting a air locker in the rear diff, but was advised against it, as the posi unit will allow some slippage, where the air locker would not, and would cause serious handling problems. On the other hand, my Trans Am has the 9 bolt posi unit. It handles well on the highway, but the car fishtails like crazy on dirt roads, and I can only imagine what it would be like on ice. I believe it has more to do with weight and balance then if it is has posi traction or not. The T/A is obviously nose heavy, where the SUV weighs in just shy of 5K, and is almost balanced. Your Camaro will probably have completely different handling characteristics with a posi unit, then your Astro van will with a posi unit. A nurse friend of mine drives her Astro AWD through all kinds of weather, and it has a posi rear diff. Charles

You'll be able to start from a stop better, but you'll have a greater chance of fishtailing when you take corners during acceleration. I had both options during the winter and I prefered the posi. You just have to pay more attention when you drive.

Plus, donuts are so much fun to do when it's slick out =)

if the tires start to spin with posi you are going to kick sideways, if only one starts to spin, like in an open or crappy lsd than the car will still go straight. posi will help you in the rain as long as you don't matt your foot. no matter what you do your car will not be good in the snow, so keep it in the garage and away from the salt

The risk of fishtailing is there with a regular rear end as well, because my open rear has spun me around a couple times in the rain. I just got on the acceleration a little too quickly before turning and the rear broke loose.

Go with the posi, you'll be much happier. I live in Ottawa, and my freind lives in Chelsea quebec up on a hill on country roads. Getting up the hill is always an issue, and he never had a prob with his posi, only the newer cars, like his 03 mustang.

I had a limited slip on my El Camino (aka the worst winter car/truck ever, only like 200lbs over the rear tires) and it did well the only time i spun out was when i was passing somebody in a snow storm and i hit some ice at 40 ( i know dumb ) the limited slip i think is better in rain. never had a problem of spinning around, I only spun for a second then the car went on always pointing forwards. and it's alot quieter then the gov lock which sounds like you left a piece of your car or truck behind you. my dad's silverado has one and it scares the crap out of me when it locks in!

all i can say is get good tires89 iroc with posi, had all weather goodyears on it...couldnt even get up a f777ing hill in the rain with 305tbi =/
-------------------------talked to girlfriend about this "Remember the time it rained and I was trying to go up the hill?" she laughed and said "Which hill, which time?"

I have always driven rwd in the snow and that includes 2 Firebirds, both V8's. Both had open diffs. With the open diff, its still quite easy to swing the rear around, cause if one tire breaks loose then the other gets all the tractional forces, so it usually breaks loose too. And I actually consider open diff's dangerous on snow/ice, and treacherous on hills in these weather conditions. I've had tires rated in the Ultra High Performance All season catagory that werent worth a crap on ice/snow. Here in my town theres a hill that seperates one side of town from the other and when the weather was too bad that hill was literally impassable. Only way to get up it was with the gas pedal mashed and in 5th gear with the speedo reading about 110mph just to get the tire to burn through enough to get traction. Trying to get a Manual tranny to get grip with 1 tire is a lost cause. These cars are not safe on snow/ice unless they are equipped with posi. POSI IS ABSOLUTELY a benefit in bad weather. One great thing about posi in inclement weather is the predictability. You will KNOW when its gonna slip, whereas with an open diff its kind of an unknown because its so sensitive to vehicle weight displacement and such.

That one wheel peel bs damn near got me killed last winter. There is a traffic light right before a set of railroad tracks, and it was icy with over 6 inch's of snow on top of that. and it was getting slushy, when the light turned green I had to really work to even move since it just wanted to sit stuck, then it finally started creeping, as soon asI got over the tracks the rails got me stuck on them. With one tire I just couldnt get it to move. There was traffic behind so I couldnt back up, and a friggin train was coming, but fortunately it was a ways off and was slow. A truck was behind me so I asked him to push me over the rails. If I woulda had posi I never would have been in that situation, two pushers is ALWAYS better than one.

After last winter I made the decision that I wouldnt drive my birds during winter anymore. So now I got a beater dd thats much better in bad weather.

While the Posi is definitely a plus and is important, good tires are even more important. If I ever drove my Birds on the snow/ice again, I'd definitely cought up the money for a set of winter tires

Limited Slip (AKA Posi) was introduced by Auto companies as a way to improve traction in bad road & weather condition and was not sold orignally as a performance option.

well not all posi and limited slip rear ends are the same. Auburn uses to cone and is limited slip (takes little longer to engage in my opinion) then there is gov lock which uses a flat clutch pack (known to burn out easy if you don't have the correct fluid or level. Then there's the air lockers (ya they use air to engage, usually extreme duty or rock crawling, or wheeling) Then there is the classic setup that GM has used forever.

Before you get one though know what you are doing they can be tricky and if you have ABS they can be very specific sometimes.

Posi...POSITRACTION=Chevolet trade name for a limited slip used in the 60's. No such item as a Posi rear-No mater what the internals are they are still a limited slip.

I call my current rear "Unlimited Slip". Also known as the "Peg leg".

I have a 9 bolt Aussie sitting in the garage with a 3.27 limited slip waiting for funds to replace the peg leg.

Can't wait.

I don't think it is as big a factor as many people make it. FWD vs RWD vs 4X4 vs posi or open diff. It is knowing what the vehicle can do and is capable of. I have driven an old 86 Sunbird with a 2.0 4 popper in some pretty deep snow and passed more than one 4X4 after they slid off the road and augered in pretty deep. I knew if I stopped I would never get going again. It is all about knowing the vehicle and driving technique.

You have to be smarter than what you are doing/working on.

mine's a one-wheeler-squealer and i've driven it in everything including freezing rain. it is not only possible but quite easy to break the rear loose driving in a straight line on glare ice. a limited slip will benefit you in that type of weather only as long as you use a feather touch on the gas. but then nobody should ever drive cars like ours in that weather anyway...