Transfer case? Sport vs Rubi vs Atlas

ChattVol

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Recommendations appreciated...I'm looking to improve offroad climbing on a 6 speed jlus without breaking the bank. It's lifted 2.5" with 35" ko2's with swapped in jlur axles/brakes/lockers/4.10 gearing. When I want to climb controlled and slow in 4wd low with sport 2.72:1 transfer case, the 5.13 1st gear struggles a bit and I have to feather the clutch alot to not stall.

I've researched regearing to 4.88 and going to 37s and/or swapping in a rubi 4:1 transfer case, but they are $1800 ish new + labor and then offsetting some of the cost selling my t case for $500 or so. I've also searched some salvage yards and the automatics rubi t cases are going for $1300 and no manual t cases are available yet. I would have to have the manual t case according to Magna.(mfg of t case)

As it stands, I've decided to stick with the 35's and 4.10 gearing. My question is...does it make sense to swap in a salvage rubi t case for $1300 + labor or look at a Atlas t case for slightly more or would regearing to 4.88 noticeably improve the crawl ratio? I DD the jeep and offroad once a month and prob eventually go to 37s tire size. Thoughts?
@doug_outlawoffroad @rustyshakelford
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rustyshakelford

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Recommendations appreciated...I'm looking to improve offroad climbing on a 6 speed jlus without breaking the bank. It's lifted 2.5" with 35" ko2's with swapped in jlur axles/brakes/lockers/4.10 gearing. When I want to climb controlled and slow in 4wd low with sport 2.72:1 transfer case, the 5.13 1st gear struggles a bit and I have to feather the clutch alot to not stall.

I've researched regearing to 4.88 and going to 37s and/or swapping in a rubi 4:1 transfer case, but they are $1800 ish new + labor and then offsetting some of the cost selling my t case for $500 or so. I've also searched some salvage yards and the automatics rubi t cases are going for $1300 and no manual t cases are available yet. I would have to have the manual t case according to Magna.(mfg of t case)

As it stands, I've decided to stick with the 35's and 4.10 gearing. My question is...does it make sense to swap in a salvage rubi t case for $1300 + labor or look at a Atlas t case for slightly more or would regearing to 4.88 noticeably improve the crawl ratio? I DD the jeep and offroad once a month and prob eventually go to 37s tire size. Thoughts?
@doug_outlawoffroad @rustyshakelford
Or any others?
Man that’s a tough one. We have the 4:1 rubi case and 5.13 gears. Our crawl ratio is awesome. If you’re wanting to go up to 37s I would recommend addressing your gearing with the 6 speed. After that’s done, then look into an atlas. I wouldn’t pay 1300 for a takeout case but haven’t priced an atlas either. The gears will be a noticable improvment in drivability.

Brett
 
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ChattVol

ChattVol

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Man that’s a tough one. We have the 4:1 rubi case and 5.13 gears. Our crawl ratio is awesome. If you’re wanting to go up to 37s I would recommend addressing your gearing with the 6 speed. After that’s done, then look into an atlas. I wouldn’t pay 1300 for a takeout case but haven’t priced an atlas either. The gears will be a noticable improvment in drivability.

Brett
Thanks for feedback...to be clear, the on road driveability is fine now with 4.10's and 35s. I'm referring to improving offroad controlled climbing in 1st gear so I dont have to ride the clutch. Is there a crawl calculator?
 

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Thanks for feedback...to be clear, the on road driveability is fine now with 4.10's and 35s. I'm referring to improving offroad controlled climbing in 1st gear so I dont have to ride the clutch. Is there a crawl calculator?
If you go to 37s I don’t think you’ll be happy with on road or off road. That’s what I’m getting at. I would address the gears and go from there.

Here’s a calculator I used. Just real quick your crawl is like a 57. Change to 5.13 gears it’s a 71. Keep 4.10 and do 4.1 it’s 80 something. I would want the benefits of the gears all the time vs only when it 4l personally.

https://www.rocky-road.com/calculator.html

Brett
 
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ChattVol

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If you go to 37s I don’t think you’ll be happy with on road or off road. That’s what I’m getting at. I would address the gears and go from there.

Here’s a calculator I used. Just real quick your crawl is like a 57. Change to 5.13 gears it’s a 71. Keep 4.10 and do 4.1 it’s 80 something. I would want the benefits of the gears all the time vs only when it 4l personally.

https://www.rocky-road.com/calculator.html

Brett
Thanks...what rpm are you at in 6th gear at 70mph? I thought 4.88 gearing and 37's are a little stronger than stock 4.10 and 33s? Arent 4.88 and 37s similar to stock and optimal for power/gas mileage?
 

rustyshakelford

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Thanks...what rpm are you at in 6th gear at 70mph? I thought 4.88 gearing and 37's are a little stronger than stock 4.10 and 33s? Arent 4.88 and 37s similar to stock and optimal for power/gas mileage?
At 70 I’m around 2400-2450ish. My average mpg for this tank and I’m less than half is 16.6. Have tons of power and drives great. 35s would be great with 4.88s but if you want 37s the 5.13s are nice. Not many people have the 6 speed so the mentality has to be different. The same for one isn’t the same for the other.

Brett
 
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ChattVol

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At 70 I’m around 2400-2450ish. My average mpg for this tank and I’m less than half is 16.6. Have tons of power and drives great. 35s would be great with 4.88s but if you want 37s the 5.13s are nice. Not many people have the 6 speed so the mentality has to be different. The same for one isn’t the same for the other.

Brett
Yeah...seems like the 6 speed isnt as efficient and needs stronger gearing than the auto. Is your 16 mpg mixed city and hwy driving? With 35s and 4.10, mine gets 20mpg on hwy at 70mph and 16 around town.
 
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If you go to 37s I don’t think you’ll be happy with on road or off road. That’s what I’m getting at. I would address the gears and go from there.

Here’s a calculator I used. Just real quick your crawl is like a 57. Change to 5.13 gears it’s a 71. Keep 4.10 and do 4.1 it’s 80 something. I would want the benefits of the gears all the time vs only when it 4l personally.

https://www.rocky-road.com/calculator.html

Brett
According to that calculator that oddly doesnt factor in tire size, transfer case ratio makes alot bigger impact on crawl ratio. Baseline 5.13 1st gear with 4.10 diff gearing and 2.72 t case is 57 crawl ratio. 4.10 gearing with 4:1 t case results in a 84. 4.88 gearing with 2.72 t case only raises crawl ratio to 68.
 
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ChattVol

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At 70 I’m around 2400-2450ish. My average mpg for this tank and I’m less than half is 16.6. Have tons of power and drives great. 35s would be great with 4.88s but if you want 37s the 5.13s are nice. Not many people have the 6 speed so the mentality has to be different. The same for one isn’t the same for the other.

Brett
When you regeared, did you buy the master overhaul gear kit for $1050 ish or just the ring and pinion for $600?
 

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When you regeared, did you buy the master overhaul gear kit for $1050 ish or just the ring and pinion for $600?
Yes. G2 is also offering gears. They are cheaper than the Dana spicer at around $950. Haven’t installed any of them yet

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Yes. G2 is also offering gears. They are cheaper than the Dana spicer at around $950. Haven’t installed any of them yet

Brett
Good...I'm hoping some folks start to upgrade to Atlas and sell their rubi t case.
 

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As Iv mentioned before even with 5.13’s it’s not low enough with 37’s. I’m at 71:1. In the bigger rocks/ steep sections is where the issue is. 4:1 case would take me to 105:1 and would solve the issue.

An atlas would be cool but you’ll need new driveshafts, likely a custom t case skid made and maybe have to cut up the center console to fit the twin sticks. Price I think around 2200-2500

One thing I didn’t mention about the rubi case being $1800 is that the dealer also adds 1000 core fee. So it’s $2800 until you give them your sport t case..that was disappointing.

I have not tried to find a rubi t case at a salvage yard yet. Of course, the manual trans t case is a unicorn too.

All of that said I will likely be buying a case through the dealer..installing myself and returning my sport case. I should have just bought an auto but I had such a bad taste in my mouth about autos..I had the JK 4 speed 42rle..terrible.
 
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As Iv mentioned before even with 5.13’s it’s not low enough with 37’s. I’m at 71:1. In the bigger rocks/ steep sections is where the issue is. 4:1 case would take me to 105:1 and would solve the issue.

An atlas would be cool but you’ll need new driveshafts, likely a custom t case skid made and maybe have to cut up the center console to fit the twin sticks. Price I think around 2200-2500

One thing I didn’t mention about the rubi case being $1800 is that the dealer also adds 1000 core fee. So it’s $2800 until you give them your sport t case..that was disappointing.

I have not tried to find a rubi t case at a salvage yard yet. Of course, the manual trans t case is a unicorn too.

All of that said I will likely be buying a case through the dealer..installing myself and returning my sport case. I should have just bought an auto but I had such a bad taste in my mouth about autos..I had the JK 4 speed 42rle..terrible.
Atlas case will require an adaptor and will be in the $3600 range.
 

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Atlas case will require an adaptor and will be in the $3600 range.
oh wow so they are not doing a 2 speed at all? I wouldnt want a 4 speed atlas. I dont think they have ever made a 3 speed.

The JK verision is 2200 ish and is a 2 speed
 

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