whats anti spin rear diff?

I was lookin at the build sheet and it says anti spin rear diff is that lole a locking diff? When i turn sharp on a paved road that has some sand on it i can hear one tires trying to spin

We've gone round an around on this one here before (no pun intended) on the various names the factory has for various versions of what used to be understood as three very clear, simple choices; Open, Limited Slip and Locking rear ends.

I think we all came to decide that the "new" RAM term for anti-spin is a Helical Limited Slip.

The first step, the "Open" diff gets confused, as "Traction Control" takes over and tries to make it act like a Limited Slip, but is just electronic.

I think the difference, or so I have come to understand it, is that Anti-Spin means there is a mechanical difference, rather than just electronic intervention.

I hope that makes sense.

If I am wrong, surely on Monday morning there will be 20+ people in here to rub it in my face and set us both straight.

Yeah it's essentially an in house name for Positraction aka Sure Grip aka Q2 aka Trak Lok aka a whole mess of names that all boil down to some form of mechanical limited slip rear differential.

My build sheet also states I have an anti-spin rear differential axle.

So does this mean I need to add mopar limited slip additive / friction modifier when I change my rear diff fluid? If so, they kind of hosed that grammar up.

Yes that means you need to put in the limited slip additive when changing the diff fluid.

What's anti spin rear diff? A factory lsd unit

"anti spin differential rear axle" is exactly, letter for letter / word for word, what the build sheet says.

okay okay, I'll add the limited slip additive.

Thanks Guys

Most differential oils already come with the friction additive already in it. Just read the bottle to make sure it isn't there. If you have a clutch based LS, you don't want to add too much. If it is gear driven, none is needed.

Well my differentials are completely stock. Just got done doing a ton of maintenance. Was breezing through the owners manual, and there it was........no friction modifier is needed in 10.5" and 11.5" rear differentials. States it right in there, just in case anyone else needs to know.

Prormk said:

Well my differentials are completely stock. Just got done doing a ton of maintenance. Was breezing through the owners manual, and there it was........no friction modifier is needed in 10.5" and 11.5" rear differentials. States it right in there, just in case anyone else needs to know.

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Friction modifier is only needed for clutch based limited slip differentials. If the factory ever used gear driven LSDs it would not need the additive.

The easiest way to know is to jack up the rear axle by the pumpkin (differential) and spin one tire with it in N and brake off. If the other spins in the opposite direction, it is open, if they both spin in the same direction, it is limited slip or locked.

1500's have clutch type limited slips, 2500's & 3500's have helical gear limited slips. Sooooooo.......... 1500's need the friction additive, HD models do not.

6.7CumminsDrvr said:

1500's have clutch type limited slips, 2500's & 3500's have helical gear limited slips. Sooooooo.......... 1500's need the friction additive, HD models do not.

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It never hurts to have the additive (as long as you put in the right amount). But it does hurt things if you don't add it and need it (have clutch based LSD).

Simplest solution, use gear oil that already has the additive in it (it will say it on the bottle), and never have to worry.

Here's a good article on how it works. Clutch-type Limited Slip Differential - HowStuffWorks

So I checked my window sticker and the build sheet. Not say anti-spin rear diff. Just to be sure I jacked the rear end off the ground trans in N. Spun the drivers side tire in a reverse direction and the passenger spun in the opposite. So. Open diff? I've spun the tires a couple time leaves two lines.

CC12RamLove said:

So I checked my window sticker and the build sheet. Not say anti-spin rear diff. Just to be sure I jacked the rear end off the ground trans in N. Spun the drivers side tire in a reverse direction and the passenger spun in the opposite. So. Open diff? I've spun the tires a couple time leaves two lines.

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If it is a 1500, open diff. The gear driven limited slip in the heavy duty trucks will spin the tires like that, but a 1500 should have them both going the same way.


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jwheeler said:

If it is a 1500, open diff. The gear driven limited slip in the heavy duty trucks will spin the tires like that, but a 1500 should have them both going the same way.


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That's off my build sheet I down loaded today. So it lies? Well that's sucks. If its an open dif, would both tire lay track when I smoke them? Not that I want to waste the rubber again, but it would nice to know for sure.

CC12RamLove said:

View attachment 51360

That's off my build sheet I down loaded today. So it lies? Well that's sucks. If its an open dif, would both tire lay track when I smoke them? Not that I want to waste the rubber again, but it would nice to know for sure.

Click to expand...

Could test it out on dirt or grass. Less wear on the rubber.

Squidbilly said:

Could test it out on dirt or grass. Less wear on the rubber.

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Had to try. short but both spun.

.

Okay. So im going to explain it in the way that I understand it to be, which i assume is correct, but i may be mistaken.

Open Differential: Quite simply, it never locks, or 0% locked 100% slip. Basically the power goes to one wheel and allows the other wheel to spin freely. PROS- allows the vehicle to rotate faster around a corner which improves turn radiuses CONS-diminished stability in straight lines and can be difficult to get the power down because 100% of the power is to one wheel which has limited traction

Locking Differential/Locker: unless separately manually engaged, these are always locked, or 100% lock 0% slip. This means the power goes to both wheels equally. PROS- best possible traction under WOT (wide open throttle) and best straight line stability. CONS- can become tail-happy in less-than-ideal conditions and because locked diffs never slip, turning becomes increasingly difficult

Thats where limited slip diffs/anti-spin diffs/ anti-slip diffs/ whateveryouwanacallit diffs come in
LSD/ASD: there is a preset "setting", if you will, that determines when it locks. Lets say its 50/50 lock/slip. The diff will allow the wheels to spin up to or about 50% power, at which point it locks. PROS- slip allows it to turn while lock allows it to put power down and increase stability. CONS-might be a little touchy in the rain or snow (buts thats the best par).

All of these are mechanically based. There are also electronic diffs like in the Ford Focus RS which is basically a complex electronic traction control to allow more or less slip. I may be wrong, but im quite confident the diffs in all our trucks are mechanical

CC12RamLove said:

View attachment 51360

That's off my build sheet I down loaded today. So it lies? Well that's sucks. If its an open dif, would both tire lay track when I smoke them? Not that I want to waste the rubber again, but it would nice to know for sure.

Click to expand...

If it is on the build sheet, it probably has it. I looked into it a little and the tires spinning in the opposite direction is probably normal on the newer ones. The clutches are not preloaded like the older axles. Pressure is applied to the clutches when they are under load and they will start to grip. But will slip with zero load (like when they are in the air). Supposed to be for fuel economy, less drag when turning.


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