No limited slip in my v6.....

RangerMan said:

Don't go with a 9-inch you won't be making the power to use all that beef and will just end up being slower.

Wait around for the wrecked GT's to start showing up and grab the 8.8" off one for cheap

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echo7 said:

I was told in a thread before the server crash that there where limited slips in the v6's stock, but today i made sure to look when my car was up gettin my new bullitt rims put on, spin the tire one way, the other spins opposite, so no limited slip.QUOTE]



I'm pretty sure that if it'sin the air, and you spin a tire one way, posi means it should spin the opposite. If you had a straight-up locker diff, then both wheels would spin foward if you rolled one forward.

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fazm83 said:

Limited slip differentials will spin the opposite way, and a posi rear will spin the same direction.

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Svtpilot said:

There seems to be alot of miscinceptions about Diffs so here we go, differentials 101:
There are 3 types of differentials:
Open rears
Limited Slips
Spools a/k/a Locked rears
Limited slip and Posi are the same thing (and BTW altough "posi" has become a generic term for limited slip like "Coke" is for cola, it is actually a Chevy term. Fords have Traction-lok). Limted Slip rears use clutches, though some like a Detriot Locker use a ratchet assembly, to send power to the wheel with traction. Since normally both wheels have equal traction, when you light up the tires on a limited slip equipped car both tires will spin.
An open rear sends the power to the wheel with less restistence. which is why you see cars stuck with one tire on snow spinning like crazy and one tire on dry pavement not moving.
Lastly are Spools or "locked rears" which are used excuslively in Drag Racing. Technically Spools are not differentials. Spools have no spider gears, just a solid piece of metal with the Ring Gear Bolted to it and splines for the Axles. With Spools both tires spin at the same speed all the time regardless od conditions. This makes turning difficult since when you turn the outside wheel covers more ground then the inside and therefore has to spin faster.(Which is why cars have differentials in the first place,to allow the wheels to spin at DIFFerent speeds.) Because of this Spools are no good for street use.
Normally when on a lift if you spin the tire on a car with an open rear they ill spin in the opposite direction. With a posi the will spin in the same direction and of course the same is true with a Spool. This is true probably 95% of the time, but it is not a 100% accurate way to detremine what type of Diff a car has. The only sure way is to pull off the cover and look at it.

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sam_abuelsamid said:

You are basically correct here but I would like to elaborate a little. There are quite a few different mechanisms for limited slip differentials. There is your basic clutch pack lsd (like various fords including the mustang use). There are also other types of clutch based systems, like conical clutches (I forget which brand uses these). There are worm/gear based systems like the Torsen and Quaife. There are locker types which if I recall correctly using some sort of centrifugal clutch and locking mechanism. There are also viscous coupling systems which use interleaved plates in a silicone fluid. In short there are many different kinds, and they have different locking and torque transfer characteristics. One thing they all have in common is that at low speed differentials (Such as spinning one tire on the hoist) the wheels will spin in opposite directions.

The reason they are "limited slip differentials" is because up to some threshold, they act as an open diff. Once the speed/torque differential across the differential exceeds some threshold, they start to transfer torque from the slipping wheel to the non-slipping wheel. Spinning one wheel when the car is on a hoist proves nothing. One last thing to keep in mind is that the ford lsd is a pretty crappy and even the 8.8 inch doesn't transfer much torque. The Traction control system is much more effective than the lsd.

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Svtpilot said:

Hey I said it was "Differentials 101" Now you're giving them Differentials 2 or Advanced DIffs
As far 7.5 vs 8.8 I wasn't speaking about the ability to transfer power, I was refering to durability. Unless Ford has improved it over the years which is possible, the 7.5 is no where near as durable as the 8.8. And I agree that spinning a tire is not a sure way to determine the type of diff, as I said the only sure way is to pull the cover and look at it. However in most cases they will react as I stated.

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sam_abuelsamid said:

Sorry, I wasn't trying to dispute what you said, just elaborate a little for the sake of anyone who was interested. I am just trying to share the benefit of some the experience I gained over the years to slip control development (abs/tc/vsc) and testing vehicles with different drivetrain configurations. You are right that the 8.8 should be more durable than the 7.5 axle. However, there have been a lot of advancements in metallurgy, metal forming and machining and heat treating in the last 20 years, and a 7.5 diff today is undoubtedly more durable than one from 15-20 years ago. The limited slip mechanism that ford uses in there traction-lok still blows though, and tc will give you more benefit than the oem lsd. Many of the aftermarket units are better than the factory unit, but whether they are better than the tc and worth the cost is a question I will leave open for now.

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