392 Transfer case

[Bayrat]

Just curious, in reading the Jeep description of the transfer case Quadra-Trac® SRT® 4x4 System it sounds almost as though this is their top of the line. So I'm wondering what exactly we have with the Select Trac as opposed to our dependable Rock Crusher box we've always seen.

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[IdahoJOAT]

I'm getting reports the xsfer cases are the same in the 392 and 4xe, is this true?

 

[Bzinsky]

Just curious, in reading the Jeep description of the transfer case Quadra-Trac® SRT® 4x4 System it sounds almost as though this is their top of the line. So I'm wondering what exactly we have with the Select Trac as opposed to our dependable Rock Crusher box we've always seen.

Mp3022: yes same as 4xe, but they disabled the 2wd option in the 392.

It is basically an old school box with an added feature, awd.

They called it “auto 4wd” but in operation it’s effectively awd. Imagine being in traditional 4wd, but instead of the front driveshaft being locked to the rear driveshaft, it uses what is effectively a clutch based center differential to send power to the front tires. It can only adjust the power sent to the front. It seems to operate on throttle position, more throttle = more power to the front. At low throttle you should essentially be 2wd.

A similar system has been in pickup trucks for awhile, I’ve had it since 2014 in my truck. I absolutely love having all the benefits of an awd system and all the benefits of a traditional 4wd system.

 

[Bzinsky]

Also I don’t believe they tell you to do this in the jeep manual, but they do in the trucks.

If you’re driving around on a slippery surface like sand, snow, or mud, I would use 4hi instead of 4auto. No sense in potentially overheating the clutches with constant operation on a slippery surface.

 

[3TV]

Also remember that the MP3022 transfer case has a 2.72:1 gear reduction, whether it is in a pickup truck, a 4XE Sahara, or a 392 Rubicon XR. So the 392 Rubicon does not have all of the features a regular Rubicon has. It is lacking the 4:1 gear reduction in the transfer case.

 

[Bzinsky]

Also remember that the MP3022 transfer case has a 2.72:1 gear reduction, whether it is in a pickup truck, a 4XE Sahara, or a 392 Rubicon XR. So the 392 Rubicon does not have all of the features a regular Rubicon has. It is lacking the 4:1 gear reduction in the transfer case.

Probably a good thing it doesn’t have that. just guessing, what’s it like 75:1 total torque multiplication with the 4:1 transfer case?
Well 470ft lbs of torque with 75:1 torque multiplier = damn

 

[Bayrat]

Mp3022: yes same as 4xe, but they disabled the 2wd option in the 392.

It is basically an old school box with an added feature, awd.

They called it “auto 4wd” but in operation it’s effectively awd. Imagine being in traditional 4wd, but instead of the front driveshaft being locked to the rear driveshaft, it uses what is effectively a clutch based center differential to send power to the front tires. It can only adjust the power sent to the front. It seems to operate on throttle position, more throttle = more power to the front. At low throttle you should essentially be 2wd.

A similar system has been in pickup trucks for awhile, I’ve had it since 2014 in my truck. I absolutely love having all the benefits of an awd system and all the benefits of a traditional 4wd system.

Perhaps I did not fully understand the new box features. Having owned true full time four wheel drives such as a couple of Dodge Power Wagons of old and one GM with the same features, there was a clutch pack/differential in the transfer case which allows the front and rear axles to turn at different speeds and that is how they could run on dry pavement without issues. In these new cases, my understanding is there's an electronic engage and disengage which lives outside of the box. This sets up a defined lag in the connection, one reason I do not like the way my bride's Grand Cherokee operates. Rather than smoothly applied power, there is a "grab" and sometimes a clunk sound when this occurs. You are 100% correct, lock it in if really needed because the other system is whack a mole.

 

[Hpc3]

Probably a good thing it doesn’t have that. just guessing, what’s the like 75:1 torque multiplication with the 4:1 transfer case?
Well 470ft lbs of torque with 75:1 torque multiplier = damn

Yep totally unnecessary in the 392 configuration.

 

[Bzinsky]

Perhaps I did not fully understand the new box features. Having owned true full time four wheel drives such as a couple of Dodge Power Wagons of old and one GM with the same features, there was a clutch pack in the transfer case. In these new cases, my understanding is there's an electronic engage and disengage which lives outside of the box. This sets up a defined lag in the connection, one reason I do not like the way my bride's Grand Cherokee operates. Rather than smoothly applied power, there is a "grab" and sometimes a clunk sound when this occurs. You are 100% correct, lock it in if really needed because the other system is whack a mole.

The front axle disengage and engage on my truck is done when you switch it from 2wd to 4auto.

I’m pretty sure it works the same way on the 4xe. I’m also pretty sure the 392 just doesn’t even have that part because you don’t have selectable 2wd.

There is no clunk in my 4xe or my truck. Smooth as if it’s already in 4hi.

Maybe your wife’s grand cherokee engages the front axle on the fly or something?

 

[Bayrat]

The front axle disengage and engage on my truck is done when you switch it from 2wd to 4auto.

I’m pretty sure it works the same way on the 4xe. I’m also pretty sure the 392 just doesn’t even have that part because you don’t have selectable 2wd.

There is no clunk in my 4xe or my truck. Smooth as if it’s already in 4hi.

Maybe your wife’s grand cherokee engages the front axle on the fly or something?

Hers is the top of line offering similar to the one she had in her 2001 Cherokee 4L. The clunk is when it is in 4hi and it has to grab on for traction ie the thing locks up. Never had that in the true full time units in either 4hi or 4low or hi or low Lock.

 

[Fast-n-Furious]

Looked at my 2022 392 XR and the transfer case looks different from the regular JL. At least the fill plug is on the left on mine.

 

[Bayrat]

Possibly due to clearance issues?

 

[Quadjeeper]

Yep totally unnecessary in the 392 configuration.

I beg to disagree. As far as power/torque you are correct. But for downhill, slow low range/1st gear engine braking it lacks compared to the 4:1 in the regular Rubicon. I had a '20 3.6 Rubicon that I never needed brakes on downhill technical stuff but with the 392 had to ride the brakes, which I prefer not to need to do. Trade offs.

 

[J.Ralston]

Why would they not have the 4:1 on the 392? I literally just ordered one with the Xtreme Recon package because I hate the eTorque. But I love the 4:1 TC. Great, so now I have decisions to make…

So could I take the 4:1 transfer case from my existing JLUR that has the 3.6 liter V-6 eTorque and put it in the 392 when it comes in?

 

[XtremeRetard]

Mp3022: yes same as 4xe, but they disabled the 2wd option in the 392.

It is basically an old school box with an added feature, awd.

They called it “auto 4wd” but in operation it’s effectively awd. Imagine being in traditional 4wd, but instead of the front driveshaft being locked to the rear driveshaft, it uses what is effectively a clutch based center differential to send power to the front tires. It can only adjust the power sent to the front. It seems to operate on throttle position, more throttle = more power to the front. At low throttle you should essentially be 2wd.

A similar system has been in pickup trucks for awhile, I’ve had it since 2014 in my truck. I absolutely love having all the benefits of an awd system and all the benefits of a traditional 4wd system.

I thought I read it also uses abs sensors etc to adjust the torque as required for max traction via the variable clutch etc.

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