Posi is short for "Positraction". It's a marketing term introduced by the Eaton Corporation for limited-slip differentials. A limited-slip differential is a type of diferential that is intended to spin both wheels if the speed difference between them becomes too great..
Then, how does a posi rear end work?
Positraction units prevent loss of traction by sending power to both driven wheels. At the same time, each wheel rotates independently when necessary, preventing the non-slipping wheel from losing power. A slipping wheel loses power with the conventional rear end design.
what is a posi traction? TOM: Actually, Jeannie, "posi-traction" is just Chevrolet's name for limited slip differential on passenger cars. But because of the way the differential works, when one wheel starts to slip, ALL of the power is then delivered to THAT wheel. That doesn't help you much if that wheel is stuck on snow or ice.
Correspondingly, is posi same as limited slip?
Posi means that both of the drive wheels always spin at the same speed all the time. Limited slip allows one wheel to spin fast than the other for better turning, but if it detects one wheel spinning much fast than the other it makes them both lock up and spin.
Is limited slip better than open?
Since an open differential directs more power to the wheel with the least amount of resistance, in the event of a loss of traction when turning, drivers will more easily lose control. Limited-slip differentials distribute wheel power where needed, reducing traction loss around turns.
Related Question Answers
How can you tell if you have limited slip?
The easiest way to tell if you have an open differential is to jack up the car and spin one of the rear tires. If the other wheel spins in the opposite direction, you have an open differential. If it spins in the same direction, you have a limited slip differential, or LSD.Does changing differential fluid make a difference?
Front-drivers typically integrate the differential in the transmission housing and share the same fluid. The differential oil lubricates the ring and pinion gears that transfer power from the driveshaft to the wheel axles. Changing this oil is just as important as changing your engine's oil, and for the same reason.Why do truck tires only spin?
Why are cars called "2-wheel drive" when they only spin one of the wheels? Both wheels do spin if the surface is dry, the reason why you only saw one wheel spin has to do with gears in the axel. When a car around a corner one wheel has to travel faster than the other or the tires would skip.Why is a limited slip differential Good?
Limited-slip differentials distribute wheel power where needed, reducing traction loss around turns. Better management of wheel rotation increases handling, traction and safety from spin-outs during quick turns.What happens if you run out of differential fluid?
If left too long or if the fluid starts to run low, the differential will become noisy and can eventually fail. If that happens, the gears can seize, locking up the rear wheels and potentially causing a lot of damage or even an accident.Does a limited slip differential help in the snow?
Better cars will use a limited slip differential, which will recruit whichever wheel on an axle that has more traction to help out. This actually works against you in the snow, you need a certain degree of wheel spin while climbing slippery hills or similar. Anti-Lock Brakes: You know what these are and what they do.How long can you drive with a bad differential?
A rear differential service consists of removing the rear differential cover, cleaning any old fluid from inside the differential case, resealing the cover, and adding clean fluid. After a rear differential fluid change, most vehicles will go 20,000 to 40,000 miles before it's due again.What happens if rear differential goes out while driving?
Depending on the vehicle and the issue the rear differential has, what happens when the rear differential goes out while driving varies in severity. If you have broken gear teeth or badly chipped teeth then you will experience a soft of “skip” in power or vibration that increases with speed.Can you drive with broken rear differential?
They're what transfers power to the wheels from the transmission (in a front-wheel drive setup) or the differential (in a rear-wheel drive system). If one of your axles is broken, do not drive the car. It's not safe. If your axles are failing, you'll still technically be able to drive your car.What the difference between a locking differential and limited slip?
Limited-slip differentials are considered a compromise between a standard differential and a locking differential because they operate more smoothly, and they do direct some extra torque to the wheel with the most traction compared to a standard differential, but they are not capable of 100% lockup.How do you know if you have a bad differential?
There are many signs that will let you know that your differential needs to be repaired or replaced. One of the most obvious signs is a loud whirring noise that takes place when your vehicle is decelerating. You also may hear a howl or a whine when you are accelerating. This can be symptomatic of a bad differential.How do I know if I have a g80 differential?
look in your glovebox & you'll find a label that has a bunch of 3 digit codes. they're in alphabetical order. Work your way down & over until you see G80. Once you see the G80 code, go ahead & start saving your money for a truetrac.Is limited slip differential worth it?
In a limited-slip differential, engine torque is distributed evenly to each wheel on the axle. Ideally, it is better to drive on roads that are clear when you have this differential. But if you drive over mud or ice on the road, one of your wheels may lose traction as it spins.What makes a rear end posi?
It has to do with the rear end differential which is responsible for making the wheels turn or spin rather. Posi Traction was GM's trademark for their limited slip rear ends in the 60s. Other vehicles (Ford ) use limited slip…same thing down to the part number.How do limited slip differentials work?
Limited slip differentials transmit equal torque to both wheels when driving straight. However, when one wheel spins due to loss of traction, a patch of ice, mud, too much throttle, etc., then the unit automatically provides more power to the wheel that has traction.Is a Dana 44 limited slip?
Independent rear suspension (IRS) Dana 44 axle This axle is referred to as a Dana 44 ICA or Dana 44 IRS. The majority of Corvette and Viper Dana 44 IRS set ups use a limited slip differential.How do I know if my Jeep has limited slip differential?
Rotate either rear wheel. If the wheel on the other side turns in the opposite direction, you don't have limited slip. If it turns in the same direction, you DO have a limited slip diff.Why does only one wheel spin when I do a burnout?
Originally Answered: Why is it that when you're doing a burn out sometimes one of the rear wheels spin instead of both wheels? That will happen if you have a normal “open” differential. Therefore if one wheel breaks traction and starts spinning virtually all the torque will go to that wheel make it spin even more.Is a limited slip differential good for drifting?
Because VLSD's will work well for drifting in the rain but don't offer the same performance and predictability of 2-way aftermarket differentials or a welded differential in the dry. Another thing to note for you “hardcore drifters” is that safety is a big factor as well. 
