AAM 11.5" w/Anti-Spin (Worm Gear-Torsion) type gear set.

[LF-6.7LRam]

I have read/been told the Eaton design (Anti-Spin) - worm gear/torsion type (Anti-Spin) needs a gear oil that does not contain the LS additive to perform as designed. (This unit is totally different then the Clutch Type).

Was curious if any member has experience with this?

 

[SubieRubyRoo]

What spec is called for?

 

[Big E]

It doesn't NEED a limited slip additive.

If the oil has it or not doesn't matter.

 

[PontiacHO]

That’s typically an off-road diff.

 

[LF-6.7LRam]

The Eaton rep - we chatted with replied with - the Unit to perform as designed requires (Not Recommends) a GL-5 gear oil that does not contain the LS additives.
The AAM rep - some what beated around the bush - but did reply - the unit will perform fine with a gear oil that contains the LS additives - but might not perform as well when compared to a unit running GL-5 gear oil without the LS additives.

 

[marc1]

Was curious if any member has experience with this?

Yes, I installed an Eaton Truetrac in my Chevelle. Did you have a specific question or do you want just general comments? It is a good unit, I was happy with it. Torque bias was mostly uniform under straight line acceleration, cornering bias was fine as well. I didn't think there was an advantage over my original traditional clutch style and subsequently would probably not go this way in the future where a clutch type posi is still available. I do not like the cup / cone Auburn style differentials (i.e. BOP rear ends) so in those cases, if my cup and cone are worn out, I would use the Truetrac if a clutch Eaton wasn't available. I used non-LS gear oil as per Eaton recommendations. The LS additive will affect the torque bias. How much is the bias affected, I don't know, I never tried LS oil to see the effect for myself, there was no need to experiment on that in my case.

 

[Big E]

That’s typically an off-road diff.

You are probably thinking of the Detroit Locker.

 

[LF-6.7LRam]

Locally - Automotive stores - I couldn't come across not one brand of GL-5 Gear oil that didn't contain the LS additive.
figured I would now - go to on-line ordering.

 

[Big E]

I've used both Redline and Amsoil gear oils over the years that claim to contain friction modifiers for clutch type limited slips. I have always had to add more to get my clutch types to not chatter around turns. Especially the Dana 80 with the Powerlock LS in my '96 Ram.

I have Amsoil Severe Gear in my '16 Ram for 40k now. I have not noticed any problems with the diff not working right.

IMHO it won't make a noticeable difference, but it's your truck.

 

[LF-6.7LRam]

Big E - does your 16 have the Eaton TrueTrac?

 

[marc1]

I couldn't come across not one brand of GL-5 Gear oil that didn't contain the LS additive.

That is definitely the biggest issue now. There are very few non-LS lubes out there. I am interested in what you eventually go with and how it works.

 

[Big E]

Yes. That's the factory limited slip that comes in the HD Rams with the AAM axles.

I see that Eaton does claim that friction modifiers and slippery synthetics will decrease performance, but they don't really say how much.

Looks like they recommend a 80w/90 conventional oil w/o friction modifier.

Torsen, which also makes a helical gear limited slip says it can be up to a 10% decrease in performance, but also says a small amount can reduce noise in turns.

I've had my truck up some moderately rocky trails in Moab, and didn't have any issues with rear wheel spin.

Personally I would rather have the protection of a top quality synthetic in my axle over a small improvement in limited slip performance.

 

[LF-6.7LRam]

right now I am leaning towards the Red Line GL-5 75W-90NS & Castrol Longlife 75W-90 Syntrax.
Possibly Mobil Delvac 1 (75W-90) if I can find it on sale.

 

[LF-6.7LRam]

Thanks Big E & Marc for your advice and replies.

I'm 58 - and this as planned is my last truck - & - wanted to just do things right to help it perform properly to & through retirement.

 

[c502cid]

I'm an old school Detroit Locker guy so smoothness is obviously not one of my qualities needed in a locking diff. I have Detroit's in the rear of my 84 K30 and 71 Blazer, power-loks in front of both. I would love to replace the AAM G80 Gov-lok in my 2002 GMC 3500 but I hate to say, the G80 works flawlessly. I've run with and without LS additive and I can't tell a difference in operation.

 

[LF-6.7LRam]

I'm an old school Detroit Locker guy so smoothness is obviously not one of my qualities needed in a locking diff. I have Detroit's in the rear of my 84 K30 and 71 Blazer, power-loks in front of both. I would love to replace the AAM G80 Gov-lok in my 2002 GMC 3500 but I hate to say, the G80 works flawlessly. I've run with and without LS additive and I can't tell a difference in operation.

Thank You - good to know!

 

[LF-6.7LRam]

I'll leave this hear for the rest of this topic!

https://bobistheoilguy.com/forums/threads/eaton-gear-oil-recommendations-for-the-truetrac.232583/

 

[SubieRubyRoo]

Don’t want it to turn out like this…

 

[dnewton3]

Let's be careful here ...

First of all, the OEM names for some tractions control units are different from the Eaton names (see link below).

For many years, the GM version of the AAM 11.5, from the factory, uses their "G-80" (GM designation) type of "locking" diff. (It's not a true locker, but it's a ramping-clutch type unit, but that's a story for a different time) ... I'm not sure if they still use this "locking" (ramp-clutch) system now. I don't even see that system in Eaton's line up now.

The RAM version of the AAM 11.5, from the factory, does not use that same unit, as far as I can tell. It's the "Anti-Spin", is it not?

Because the AAM is offered by many OEMs, and it has a decent aftermarket support, you must be careful that you're discussing apples-to-apples here.


The GM G-80 "locker" uses FM in the gear lube. GM has a previous statement out regarding their "grape juice" diff fluid (9986115). That statement says to not add FM to the diff; that's because their GM fluid already has FM in it, and adding more could adversely affect the bias value of the clutch pack. This unit absolutely needs FM to work properly, but not too much FM.

The TrueTrac version uses a Torsen type system. These also are sensitive the frictional effect of the worm-gear bias. These will work with FM, but they will lose a bit of their effectiveness. Generally, just a good GL-5 with no FM is the right choice for Torsen type units.

I don't see a unit called "Anti-Spin" in their catalog. Is that a name of the vehicle OEM and not Eaton?

https://www.eaton.com/us/en-us/prod...action-control/aftermarket-differentials.html

 

[BrianF]

Sorry if I'm missing anything but is this for the 11.5 in a Ram with the factory traction device? If so you may have better luck with LS additive. Reading on a Cummins forum, sounds like guys were having chatter when using 85 and 90 weights without additive.

My 3500 has about 140,000km and running group 4 80w140 with LS additive since about 40,000km. No chatter and no issues with lockup. I've run her with no load and some heavy loads in some slippery situations. Never had issues with it.