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Discussion Starter #1
1st post. Thanks for having me on board. Just drove my truck off the lot today. So far I'm very impressed. I had better love it... Anyways. As I figure out what these parts are actually, the first question I had had/have is identifying the exact manufacturer and technology used in the rear end. I know it's a 12" AAM, similar to the 11.5" used in previous models including GM 3500. I loved the G80 in my last 2 GM 3500 11.5 AAM. But I don't think my truck uses the G80. I believe it uses a Torsen clutchless LSD. Some folks dont like it as much as the G80 locker but others prefer it. Regardless, if anybody has any info on exactly what in the pig back there, please chime in.
 

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It is a torsen style LSD. Has a 2:1 torque bias ratio. No friction modifier is required and works better if none added (some have had noise issues requiring friction modifier).

Btw: It's actually a 12.5"

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Discussion Starter #4
It is a torsen style LSD. Has a 2:1 torque bias ratio. No friction modifier is required and works better if none added (some have had noise issues requiring friction modifier).

Btw: It's actually a 12.5"

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The window Sticker said 12" but I'll happily take 12.5. How do you feel this adds up to the auto locker in the GM 11.5 version? I like that differential on my 2 most recent truck.
 

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Discussion Starter #5
I believe you meant 11.5 and last I knew the bias on a 3500 is set higher for a slightly more aggressive diff.[/QUOTEIt was the 11.5 until they udgraded the 6.7 to HO version. Now it's at least the 12" or apparently maybe the 12.5?
 

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I believe you meant 11.5 and last I knew the bias on a 3500 is set higher for a slightly more aggressive diff.
Now that I think about it. It is a 11.5 that was upsides to a 12. I hadn't heard of them changing the bias. Last I checked it was 2:1.

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The window Sticker said 12" but I'll happily take 12.5. How do you feel this adds up to the auto locker in the GM 11.5 version? I like that differential on my 2 most recent truck.
In high difference in traction between sides I think the GM diff is better. For normal driving the torsen style is better.

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Now that I think about it. It is a 11.5 that was upsides to a 12. I hadn't heard of them changing the bias. Last I checked it was 2:1.

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The new 12" in the '19's are clutch type now. They also have 4.250" axle tubes, larger hubs and a different wheel bolt pattern.
 

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In a srw? Why doesn’t AAM list a 12 in diff?
I am not sure which trucks get the update. Some info says the high out put trucks and some says the max tow.

copy from this link:

New front and rear axles on the 2019 Ram 2500 and 3500 Heavy Duty have been engineered to improve durability, handle industry-leading payload and towing capabilities, and minimize NVH, as well as take advantage of opportunities to optimize weight.
The Ram 3500 Heavy Duty with the Max Tow Package uses an all-new, larger 12-inch AAM rear axle with 4.25-inch axle tubes, larger head, tail and differential bearings, and new O-ring style axle shaft hub seals. The limited-slip differential uses a friction plate design, while the serrated axle pinion and driveshaft flanges are upgraded to handle the increased torque.
The 9.25-inch AAM front axle on the Ram 2500 and 3500 Heavy Duty 4x4 include improved pinion seals and revisions to the housing to mitigate noise, vibration and harshness. The connector for the front-axle disconnect has been improved to enhance durability and the disconnect shield is upgraded for better protection from road hazards.

Link: https://www.turbodieselregister.com/threads/2-5-i-was-at-bar-last-night.265813/
 

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Discussion Starter #12
The new 12" in the '19's are clutch type now. They also have 4.250" axle tubes, larger hubs and a different wheel bolt pattern.
That's what I'm trying to verify. Seems odd they would go back to clutches after running helical gears on the recent 3500's. Any idea why? Is it a torsen style clutch system?
 

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The new 12" in the '19's are clutch type now. They also have 4.250" axle tubes, larger hubs and a different wheel bolt pattern.
I'm not seeing a different wheel bolt pattern. I'm not saying you're wrong, but I didn't see it. That would be stupid to have a two bolt pattern options.
 

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I'm not seeing a different wheel bolt pattern. I'm not saying you're wrong, but I didn't see it. That would be stupid to have a two bolt pattern options.
I think it is just the dually.

The Max Tow package returns and brings with it larger rear rotors, a 12-inch ring gear, bigger bearings and shafts, the latter requiring a larger bolt circle, so whether or not you get Max Tow every dually will have a different bolt pattern than SRW trucks. With Cummins power, only the MegaCab 4x4 2500 has a tow rating of less than eight tons.

https://www.turbodieselregister.com/threads/2019-ram-hd.265793/
 

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Discussion Starter #15
My single rear wheel came with the 12” pig according to the sticker. I also measured the discs when they were putting on my MT MTZ. The rear discs we almost 15” and the front discs were around 14”. Which makes me think I got the max tow package? The standard brakes are supposed to have smaller discs in the rear.
 

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Discussion Starter #16
It is a torsen style LSD. Has a 2:1 torque bias ratio. No friction modifier is required and works better if none added (some have had noise issues requiring friction modifier).

Btw: It's actually a 12.5"

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Is there any way I can verify this. I’m not doubting you. But I’m getting mixed info from Ram. I talked to someone at MOPAR and even they didn’t know if it was Torsen or clutch. A senior MOPAR Tech is supposed to get back to me. 3 dealers told me that it requires additive which would tell me it’s clutches. I don’t mean to obsess, but I find it odd that AAM doesn’t even list a 12” yet. I’ve never had so much trouble getting basic info on a pig before
 

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Is there any way I can verify this. I’m not doubting you. But I’m getting mixed info from Ram. I talked to someone at MOPAR and even they didn’t know if it was Torsen or clutch. A senior MOPAR Tech is supposed to get back to me. 3 dealers told me that it requires additive which would tell me it’s clutches. I don’t mean to obsess, but I find it odd that AAM doesn’t even list a 12” yet. I’ve never had so much trouble getting basic info on a pig before
Easiest way to verify without any uncertainty is to pull the diff cover and look.
 

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Discussion Starter #18
I wouldnt mind doing that but I normally change diff fluid at 1k for break in. It seems like someone must know for sure what it is. It's a 12" rear diff. No company has ever used such a large diff in a light/medium truck before. The mystery of this seems unnecessary. Somebody knows this.
 

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Just to help keep the water muddy, this is from the owner’s manual for the ‘19 2500/3500 I have with my new truck.

We recommend you use SAE 75W-85 HD Ram GL-5
Synthetic Axle Lubricant in 9.25 Front & 11.5 Rear Axles. Use
Mopar Synthetic Gear Lubricant SAE 75W-140 (MS-8985) in
12.0 Rear axles. Limited slip additive is required for limited
slip axles.

The only way to know for sure is as already posted, pull the cover and look at it.
 
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