I have a 1987 Monte carlo SS and im wondering if it is positraction or Limited slip in the differential.?

Question

Hi, Is having positraction any god? does it increase speed or restrict it??? and what is the difference between positraction and limited slip? which one is better?

Answer 1

Hi, I also have a 1987 Monte Carlo SS. Mine has a 3:73 limited slip rear end in it. The main difference between a limited slip and a posi is that a posi traction rear end has power to both rear wheels all the time. A limited slip rear end powers one wheel, but when that wheel starts to "slip" (spin) it engages the other wheel turning it into a temporary posi and allows the car to "hook up" better. For normal driving, you wouldn't be able to tell the difference between the two, only if you were racing a lot. In my opinion a posi is better as it allows you to get more traction.

Answer 2

Positraction does help with increasing speed while giving both rear tires the power to move the car. Positraction is understood as "full" and "slip" traction. Full positraction is both tires go all the time, and the slip positraction is where it sends power to both sides if it's dominate side slips. Although "full posi" sounds like the better deal, you spend more gas on it so I wouldn't say it is always better than slip.

Answer 3

My turn, my turn. LOL. Let's first clear up some misconceptions your, "friend", gave you...m'kay? First off, 0.030" overbore is not going to add that much displacement. 30 over will work out to about 355 cubic inches, not 380. Second, the 350 is not a big block, rather it is a small block. Pontiac, Buick, and Oldsmobiles had a big-block 350 in the early seventies. This is the smallest displacement big block that I know of, and they are extremely rare. These were a, "sleeved down", 394 inch GM big-blocks, and shared only the displacement with the small block Chevy. But really, this is the only source of confusion, and it is native to the SBC, because of this weirdo power-plant. The further we get away from its production date, the less people remember that there actually is such a thing as a big-block 350. They are just outrageously rare. 383 cubic inch, small-block, GM v-8's are usually the product of a bore, AND, stroke modification. This displacement is achieved when you put the connecting rods, and crankshaft from a 400 ci SBC into the .060 over SBC 350. Two superchargers? Boy, you do want some performance enhancement, don't you? LOL Twin superchargers don't exist my man. At least none that are going to do you any good. Now there are twin-TURBO setups out there, but they are a pretty difficult set up. And the reasons that you use twin turbos are different than why you only use one supercharger. There are rare instances where turbo-lag is countered by the addition of a supercharger, and both are present. But again, very rare. One blower will provide you with an almost infinite amount of added compression. Which is what its job is. In many cases this added pressure is adjustable even. Only need one. I'm pretty sure you are just thinking of a Turbo set-up and don't know it. Where do you live? I ask because if you live in a large city, you'll likely have to have the car emission tested in order to register it. There was no 350 available for that car, that year. It came standard with either the 231 inch V-6, or a 305 in V-8. So putting a 350 in it is going to mean special registration depending on where you live. That is a pretty kool body style, fairly light and rigid, and capable of handling quite a bit of power under the hood. With that said, compared to an older Monty, it can't even stand in its shadow. Be very careful getting a whole bunch more power under there. I should mention that any significant output gains with the power-plant must be addressed also with the transmission, and rear end. Much more than 50 b.h.p. over stock out-put and you are going to have to replace the tranny and rear-end on your project with better stuff. Ever hear the term, "Crate motor"? That's gear-head nomenclature for a new motor. You can buy the whole engine you are describing here, much cheaper than you could assemble it yourself. A high perf crate motor will run you about $2K, and I guarantee you, that you will be very pleased with the 250-300 horse that will make. Put a stage 2 B&M shift kit in that TH tranny, and dig up a 10 or 12 bolt rear end off of a junker somewhere. And smoke the, "Fast and the Furious", crowd like they deserve! Recipe for a good bracket racing build on that Monty: New, high-performance 350 SBC= $3000 to your front door. New electrics=$1000 Built TH350, or R700 transmision=$2500. Built rear-end=$1000. New front-end=$1500. And plan on about $2500 misc. to deal with any of the 4 or 5 million little headaches this set up is going to cause. That's about 11 or 12 thousand dollars to produce a solid, 300 horsepower car that will take the pressures of racing. I could spend that on just the engine alone, and still get beat. Conversely. An 11 or 12 thousand dollar restoration would give you a collectors item that will eventually be worth that. Never try to enhance the performance of an engine with any amount of mileage on it. You'll just finish killing it, and likely won't realize any actual benefit. Performance modifications START being productive when the engine is in top shape. That thing sticking out of the hood you are talking about, is lovingly called a bug-catcher. This has nothing to do with anything, and will fit carburetors, and certain fuel injectors. Those, "butter-fly", valves are there to prevent atmosphere from gathering near the intake while the engine is idling. You'll notice they are closed in this state, and open when you put your foot in it. At a certain point you dont want atmosphere doing anything unexpected as it can cause a backfire that can destroy an engine that likely costs $150,000. They look kool as heck on a street machine but you will realize no actual effect here. In short. You might want to cut your teeth on something a little less ambitious. The Monty would make a kool bracket racer, but its true value is as a collector piece. Before deciding to, "install a four-barrel", I'd recommend knowing what, exactly, that is.

Answer 4

Positraction and limited slip are the same thing. the only two differential types are a locker(electronic or mchanical) and limited slip. a locker lockes both drive wheels together solid where as a limited slip attempts to send the power to the wheel with the most traction.

Answer 5

You've just made a pretty common mistake. Positraction is a registered trademark name belonging to General Motors, referring to a limited-slip differential. "Positraction" and limited-slip are the same thing. Mopar called their limited-slip differentials Sure-grip. (Its called a genericized brand name, like Kleenex is to facial tissue)
I know you'll probably get a lot of feedback on this question, but you should really spend a couple minutes on the internet researching this for yourself. There are lots of good sites with pictures of how they operate, and there lots of variations on these devices.

Answer 6

Will is probably right. One way to check is to raise the rear wheels off the ground and turn them by hand (car NOT running). If they both turn in the same direction, it's posi. If they turn in opposite directions, it's an open rear end.

Answer 7

positive traction..both tires pulling at the same time
limited slip..rear end doesn't use both axles to move vehicle, only engages when both axles are needed.for pulling load, or off road use...i think...not so sure about limited slip.

Answer 8

Stock in that car is limited slip