Defective Anti-Spin LSD?

[smonska]

My 5k-mile truck has the Anti-Spin Differential $445 option on the Window sticker, Ram Build sheet shows "Anti-Spin Differential Rear Axle", and the axle itself has a tag that says "68272092AC 3.92", which if I lookup the part is 3.92 Anti-Spin.

I've noticed if I get one tire on snow or ice this winter, I get one wheel spin, and the truck barely moves, unlike other LSDs I've owned. So I was curious and jacked up the rear end, spinning one tire the other spins opposite rotation, quite freely, indicating an open diff (or at least not a clutch-type LSD).

I've seen this behavior with torsen-type diffs which act like an open when totally unloaded, but a clutch type diff should force the wheels to spin the same direction. Did the 5th trucks change to a Torsen for an anti-spin, like the 2500s, or do I just have a defective one? It sure feels like it isn't working.

Anyone jacked up their 5th gen Anti-Spin and can conclusively say their wheels spin the same way and have a clutch-type LSD?

 

[Scram1500]

My LSD works, and the wheels do turn opposite when jacked up

 

[kapinallinen2]

My 5k-mile truck has the Anti-Spin Differential $445 option on the Window sticker, Ram Build sheet shows "Anti-Spin Differential Rear Axle", and the axle itself has a tag that says "68272092AC 3.92", which if I lookup the part is 3.92 Anti-Spin.

I've noticed if I get one tire on snow or ice this winter, I get one wheel spin, and the truck barely moves, unlike other LSDs I've owned. So I was curious and jacked up the rear end, spinning one tire the other spins opposite rotation, quite freely, indicating an open diff (or at least not a clutch-type LSD).

I've seen this behavior with torsen-type diffs which act like an open when totally unloaded, but a clutch type diff should force the wheels to spin the same direction. Did the 5th trucks change to a Torsen for an anti-spin, like the 2500s, or do I just have a defective one? It sure feels like it isn't working.

Anyone jacked up their 5th gen Anti-Spin and can conclusively say their wheels spin the same way and have a clutch-type LSD?

I believe it should be a clutch type, have watched countless vids. and read articles and no mentioning of Torsen, pretty sure Ram would have bragged about it.
Also the specs. call for friction modifier in the rear diff. lube for the LS, a positive indication of a clutch type.

 

[GRAYWOLF]

Isn't "anti-spin" just the computer applying the brakes to manage the spin, as opposed to a locking differential?

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[smonska]

Graywolf, that's traction control, all Rams have that. Don't have to pay $445. ;-)

 

[kapinallinen2]

Isn't "anti-spin" just the computer applying the brakes to manage the spin, as opposed to a locking differential?

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Got open, limited slip and e-locker differentials, then there are the traction control and electronic stability controls.

 

[smonska]

Ok, i've done some more research and found pics of the stock 1500 LSDs. The Ram 1500 LSD units are a clutch-type, but come with no preload springs at all, so when there's no torque applied, it's an open diff. They rely 100% on the force of the spider gears pushing against the outside of the case when under load to create clamping force on the clutches. This also means that in low-torque situations, such as a wheel on ice, they're not of much help...

Hence why all of the aftermarket LSD units (Yukon, Auburn, etc.), and posi diffs of olde, have preload springs to make the LSD function from the start.

 

[kapinallinen2]

Ok, i've done some more research and found pics of the stock 1500 LSDs. The Ram 1500 LSD units are a clutch-type, but come with no preload springs at all, so when there's no torque applied, it's an open diff. They rely 100% on the force of the spider gears pushing against the outside of the case when under load to create clamping force on the clutches. This also means that in low-torque situations, such as a wheel on ice, they're not of much help...

Hence why all of the aftermarket LSD units (Yukon, Auburn, etc.), and posi diffs of olde, have preload springs to make the LSD function from the start.

Sounds like an attempt to improve fuel economy... while sacrificing performance.

 

[Willwork4truck]

If thats the case then an elocker would have been a better choice even for pure street trucks like what I bought. Thats unfortunate. Of course the other issue with the preloaded LSD’s is that they (Ford has been my experience) would typically be worn out (clutches) within about 60-80K and essentially back to an open diff.

For a good article on LSD’s, search for “Living With Limited Slip Differentials” from fourwheeler.com, July 1, 2010.

 

[smonska]

Sounds like an attempt to improve fuel economy... while sacrificing performance.

I don't see how it would affect mpg in any way.

I do agree having it normally unloaded makes the clutches last a lot longer. It also prevents the vehicle from fish tailing in the snow or slippery conditions which is the main complaint about LSDs, but kinda defeats why I bought it for winter. I'm fine with fishtailing, I just want to go! ;-)

When torque is applied, i.e. launching/pulling hard, the clutches get pressure and you have 2 wheels together, so it does serve a use there.

 

[Jack Whitefield]

My 5k-mile truck has the Anti-Spin Differential $445 option on the Window sticker, Ram Build sheet shows "Anti-Spin Differential Rear Axle", and the axle itself has a tag that says "68272092AC 3.92", which if I lookup the part is 3.92 Anti-Spin.

I've noticed if I get one tire on snow or ice this winter, I get one wheel spin, and the truck barely moves, unlike other LSDs I've owned. So I was curious and jacked up the rear end, spinning one tire the other spins opposite rotation, quite freely, indicating an open diff (or at least not a clutch-type LSD).

I've seen this behavior with torsen-type diffs which act like an open when totally unloaded, but a clutch type diff should force the wheels to spin the same direction. Did the 5th trucks change to a Torsen for an anti-spin, like the 2500s, or do I just have a defective one? It sure feels like it isn't working.

Anyone jacked up their 5th gen Anti-Spin and can conclusively say their wheels spin the same way and have a clutch-type LSD?

Just do the old, "apply a little brake" trick. If you're in absolute slick conditions, try turning off the traction control as well.

Finally, if all else fails, install and Auburn.

 

[Scram1500]

I find my LSD to be very capable with the traction control assisting. With that being said I have not been on pure ice yet, just moderate snow

 

[devildodge]

In the many debates about open, anti spin, eLocker we have discussed this at great length.

Open diff. Power to one wheel...the spinning one. Traction control can make an open diff perform like an anti-spin.

Anti-spin. Possible power to both wheels.
Needs wheel slip to engage...so if on a slippy surface...it kinda sucks...but traction control helps it as well.

ELocker...the only way to get both tires to have traction at the exact time you need it.
Open diff after 29 mph then helps with drive ability hence making it the same as above, and then engages again back under 25 mph.

And of course...the 15 opinions about why each is better than the other and why each is worse than the other.

Me...eLocker would be my choice hands down everytime.

 

[jdefoe0424]

Funny, I had noticed this when backing a uhaul trailer up into my driveway in 4 low on ice...Guess they didn't want to deal with them wearing out.
I have quite easily gotten it to fishtail driving in the snow. That being said, I still like it better than the "e-diff" of my BMW...it always lagged just a little bit and it was noticeable.

 

[kapinallinen2]

I don't see how it would affect mpg in any way.

I do agree having it normally unloaded makes the clutches last a lot longer. It also prevents the vehicle from fish tailing in the snow or slippery conditions which is the main complaint about LSDs, but kinda defeats why I bought it for winter. I'm fine with fishtailing, I just want to go! ;-)

When torque is applied, i.e. launching/pulling hard, the clutches get pressure and you have 2 wheels together, so it does serve a use there.

Less rolling resistance going around bends.

 

[smonska]

Anti-spin. Possible power to both wheels.
Needs wheel slip to engage...so if on a slippy surface...it kinda sucks...but traction control helps it as well.

The Anti-spin is torque input sensitive (from the driveshaft), so it doesn't need wheel slip to engage, nor does that affect the mechanism. Input a couple hundred ft/lbs in from the transmission, and the clutches are pressed against the carrier. The Traction Control, on the other hand, requires wheel slip to engage, and has a second of lag, just like the e-diff in a BWM.

The issue discovered here, is the minimum amount of torque required to achieve any meaningful clutch friction is more than can be applied on slippery surfaces with spinning.

 

[devildodge]

Yes, you are correct...I worded it wrong...but you will, sometimes, get wheel slip before it engages.

Should have said wheel may slip before engagement.

I demonstrated this last night and numerous times with my 2015.

My 99 is wore out and rarely engages right off.

Which was my point...the elocker is the only one that is engaged and ready.

 

[jdefoe0424]

Less rolling resistance going around bends.

Good point.
If you've ever driven a limited slip that's been set too tight you know what it will do...it will chirp and hop on dry pavement. I can see warranty claims coming from a mile away there.

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[Scram1500]

After a year of ownership (10K miles) I have found a situation where the anti spin won't engage. When already moving, say 10-15mph making a sharp right hand turn uphill, if the gas pedal is mashed (not that I'm trying to fishtail here ) the inside wheel spins away. Not sure if I need more friction modifier or what. Might just be the limitations of the anti spin

 

[devildodge]

Why it is called anti-spin and not no-spin