offroad with 6.4

[JonRJackson]

hey guys, considering doing a 6.4 swap and the installer asked if I wanted to go to a sport transfer case from my rubicon. says that people are finding the 4:1 with a hemi has some trouble with being able to stop when in 4 low. i can see it makes some sense logically. just wanted to reach out to you guys who have done the swap and get your thoughts. i do enjoy rock crawling, no mud or high speed offroad stuff.

thanks
Jon

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[Randonexplosion]

I think that you will find that you dont hardly need 4 low. I have a 5.3 in my YJ and even on 40s with 5.13s I use 4 hi most of the time.

Low range definitely takes more braking power to stop but at idle it shouldnt make much of a difference what motor it is.

 

[JonRJackson]

I currently have 5.13s in my gladiator on 39” KM3s. I feel like that may be over geared for the 392, but don’t. Have an real world knowledge of it. Hence why I’m here ??

 

[chadinsc]

americas most wanted 4x4 uses the rubicon transfer case on there builds with the hellcats and what not. said they have never had one brake! but you could probably email them or message people on youtube that are running amw trucks and get there opinions. i would think i would keep the stock one and if you find you don’t like it change it then. but for rock crawling and low speed work i would think the 4:1 would be desirable. amw may upgrade brakes on there trucks though?

 

[JonRJackson]

That’s exactly why I am reaching out here. I know there are quite a few guys here that have swapped. Wanted some real world experience to give me some advice.

 

[DocMike]

I'll swap you straight across for my Sport S transfer....

 

[dcmdon]

A friend of mine did a MoTec Chevy LT1 conversion and they told him that a sport transfer case was stronger. I have no idea if this is true. I'd be curious for someone who knows to comment.

 

[DocMike]

Frankly I would go the other route and....
https://www.advanceadapters.com/atlas-transfer-case-jeep-jl-2sp-builder

bolt in Atlas for the JT.

 

[RodRecket]

I'll swap you straight across for my Sport S transfer....

beat me to it

 

[JonRJackson]

Frankly I would go the other route and....
https://www.advanceadapters.com/atlas-transfer-case-jeep-jl-2sp-builder

bolt in Atlas for the JT.

But the same question would apply. 2:1, 3:1, 4;1 etc for the gear ration on the t case. I think that is the whole reason for the suggestion of going to the non-Rubicon t case is to get a better gear ratio for the extra torque of the 6.4.

I was hoping to hear from those who have done the 6.4 conversion for their thoughts on the t case differences and which they would prefer.

 

[JTPatriot]

I have the 5.7 hemi with the Rubicon transfer case. I have on occasion had it push thru my brakes, all I did was put in neutral quickly and all was well. I really like the lower transfer case for slow going and rock crawling. Had a JK with a 6.0 LS and sport transfer case and would take the Rubicon case every time.
You will be over geared with 5.13's and 39's. I have 4.88's and 38's and at 75 I am doing 2100 RPMS, offroad low range is awesome!

 

[rharr]

4:1 is good for slow speed, creeping technical work where you want a touch of momentum and engine speed but not the speed.

If you are just using 4l to get over obstacles and not doing technical work then std trans case is good.

If you are running the dunes where you need more speed but not as much as what 4h offers through the gears then the STD case is better, the 4:1 case will burn through your full range of gears to fast without offering higher speeds.

Engine size should matter, it's more about wheel speed and rpm range you want for the type of 4x4ing you do.

I have a the ecoD (which has about the same torque as the 392) and the 4:1 and I am happy with the setup as it gives me good low speed control for climbing things with a good range of usable gears for the speeds i want.

If I was in the dunes, a gas motor with higher rpms and HP and a taller transfer case would be better so i can get up to speed fast and float on the sand instead of plowing through.

 

[rharr]

I have the 5.7 hemi with the Rubicon transfer case. I have on occasion had it push thru my brakes, all I did was put in neutral quickly and all was well. I really like the lower transfer case for slow going and rock crawling. Had a JK with a 6.0 LS and sport transfer case and would take the Rubicon case every time.
You will be over geared with 5.13's and 39's. I have 4.88's and 38's and at 75 I am doing 2100 RPMS, offroad low range is awesome!

Is the transmission torque converter staying engaged at engine idle speeds because the engine rpm is to high?

In a perfect world you step on the brakes, let off the gas, your engine speed drops and your auto trany un couples, thus stopping forward drive.

Sounds like the stall speed is is setup goofy.

 

[JTPatriot]

Is the transmission torque converter staying engaged at engine idle speeds because the engine rpm is to high?

In a perfect world you step on the brakes, let off the gas, your engine speed drops and your auto trany un couples, thus stopping forward drive.

Sounds like the stall speed is is setup goofy.

There had been some talk about the torque convertor staying locked at to low of an RPM but I have not looked into any since it has not been a consistent issue.

 

[JonRJackson]

Is the transmission torque converter staying engaged at engine idle speeds because the engine rpm is to high?

In a perfect world you step on the brakes, let off the gas, your engine speed drops and your auto trany un couples, thus stopping forward drive.

Sounds like the stall speed is is setup goofy.

Yes, I it should be that way. This is all pre-sales questions. With the 513s I have some push through in 4 low with the stock engine. But I agree with ya on the converter as it should remove any torque at zero throttle.

I have the 5.7 hemi with the Rubicon transfer case. I have on occasion had it push thru my brakes, all I did was put in neutral quickly and all was well. I really like the lower transfer case for slow going and rock crawling. Had a JK with a 6.0 LS and sport transfer case and would take the Rubicon case every time.
You will be over geared with 5.13's and 39's. I have 4.88's and 38's and at 75 I am doing 2100 RPMS, offroad low range is awesome!

I was thinking the same. Guess I’ll have to get bigger tires. ?

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