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Unread 10-26-2013, 01:45 PM   #1
cbi1000
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How do the 4x4 systems work????????

Ok, so i'm trying to get my ducks in a row to buy a new JKU, just trying to determine what model to get.

Rubicon has Rock-Trac 4x4 system, the other models have the Command-Trac.

Rock-Trac seems to be:
Lockers front and rear
4.1 ratio
Disconnect sway bar

So my big questions are these:
1. In 4 wheel HIGH or LOW with the lockers turned off, is the 4x4 systems working exactly the same between the rubicon and Sport?

I understand the rubicon would have a bit more torque due to the 4.1 ratio and 410 gears, but that being said are the two systems working the same?

thanks

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Unread 10-26-2013, 02:00 PM   #2
brianjw
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In 4x4 high both operate the same. In 4x4 low they both operate the same, except the rubicon has a lower gear ratio.
The rubicon lockers only operate in 4 low below a certain speed (unless re-wired).

The 4.10 gears are very much worth it if you're planning on running larger tires. What are your plans with the jeep? Lift? Big tires? Off roading much? Looking at automatic or manual trans?
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Unread 10-26-2013, 02:16 PM   #3
cbi1000
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Quote:
Originally Posted by brianjw View Post
In 4x4 high both operate the same. In 4x4 low they both operate the same, except the rubicon has a lower gear ratio.
The rubicon lockers only operate in 4 low below a certain speed (unless re-wired).

The 4.10 gears are very much worth it if you're planning on running larger tires. What are your plans with the jeep? Lift? Big tires? Off roading much? Looking at automatic or manual trans?
Yes, I want to put 35" tires and a lift. I started another thread about a build i'm thinking about doing. Getting a Sport 24s and putting 4.88 gears and Detroit True Track lockers. But I don't know much about either of those, a jeep builder here in town told me about them.

thanks, i really did want to know if 4 wheel high and low where mostly the same in the different models.
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Unread 10-26-2013, 02:22 PM   #4
HappyTrails
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Like Brian said. The Rubicon 4LO gear ratio is 4:1 vs Sport/Sahara 4LO is 2.73:1. 4LO can be used up to 25 mph. And the Rubicon lockers can only be engaged in 4LO (unless re-wired to work in 4HI...not recommended! Turning is a ***** with the lockers engaged). The Rubicon's gear ratio is great for rock crawling.

The electronic sway bar disconnect is a nice feature, unless you plan to really off-road it (flex the suspension a lot). I've busted 2 sets of sway bars from off-roading, even though I hit the e-disco button on my Rubi. When you flex it fully, sometimes the sway bars come back up the wrong way and bend into a boomerang shape or just snap. Except in those two instances, I usually manually disconnect the sway bars.

Just depends on what you intend to do with your JK. Mud bogging, rock crawling, desert running, forest service trails, daily driver? And if you plan to do rock crawling...go with an automatic transmission.
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Unread 10-26-2013, 02:38 PM   #5
cbi1000
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Quote:
Originally Posted by HappyTrails View Post
Like Brian said. The Rubicon 4LO gear ratio is 4:1 vs Sport/Sahara 4LO is 2.73:1. 4LO can be used up to 25 mph. And the Rubicon lockers can only be engaged in 4LO (unless re-wired to work in 4HI...not recommended! Turning is a ***** with the lockers engaged). The Rubicon's gear ratio is great for rock crawling.

The electronic sway bar disconnect is a nice feature, unless you plan to really off-road it (flex the suspension a lot). I've busted 2 sets of sway bars from off-roading, even though I hit the e-disco button on my Rubi. When you flex it fully, sometimes the sway bars come back up the wrong way and bend into a boomerang shape or just snap. Except in those two instances, I usually manually disconnect the sway bars.

Just depends on what you intend to do with your JK. Mud bogging, rock crawling, desert running, forest service trails, daily driver? And if you plan to do rock crawling...go with an automatic transmission.
This jeep will my my dd, and i'm lucky enough to live in Oregon, i have mud, rocks, desert, and forest all round me. My favorite thing is forest service roads and rock crawling. Not really into mud.

thanks,
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Unread 10-26-2013, 05:08 PM   #6
222Doc
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Quote:
Originally Posted by HappyTrails View Post
Like Brian said. The Rubicon 4LO gear ratio is 4:1 vs Sport/Sahara 4LO is 2.73:1. 4LO can be used up to 25 mph. And the Rubicon lockers can only be engaged in 4LO (unless re-wired to work in 4HI...not recommended! Turning is a ***** with the lockers engaged). The Rubicon's gear ratio is great for rock crawling.

The electronic sway bar disconnect is a nice feature, unless you plan to really off-road it (flex the suspension a lot). I've busted 2 sets of sway bars from off-roading, even though I hit the e-disco button on my Rubi. When you flex it fully, sometimes the sway bars come back up the wrong way and bend into a boomerang shape or just snap. Except in those two instances, I usually manually disconnect the sway bars.

Just depends on what you intend to do with your JK. Mud bogging, rock crawling, desert running, forest service trails, daily driver? And if you plan to do rock crawling...go with an automatic transmission.
if that happens your links are to short on the E sway. they should not buckle over and hit the tie rod ever. No matter how flexed you get, unless you break a shock then the front can just drop right out.

The auto today need less gear than the manual. That is why it comes with only 3:73 stock JKR. BUT if you get a RUBI auto get the 4:10 35"s ready.
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Unread 10-26-2013, 05:24 PM   #7
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222Doc, Thanks! I will take a look at the links and see about lengthening them. I never thought about that.
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Unread 10-26-2013, 06:17 PM   #8
brianjw
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Quote:
Originally Posted by 222Doc

if that happens your links are to short on the E sway. they should not buckle over and hit the tie rod ever. No matter how flexed you get, unless you break a shock then the front can just drop right out.
Great point.
You can see the angle of my sway bar here, with a 3.5" lift sitting under its own weight.



I know people love to hate aev but at least their lifts account for this stuff!
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Unread 10-26-2013, 07:17 PM   #9
suicideking
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If you will be doing any rock crawling, you will be better off with the Rubicon because of the lower gears and transfer case, and lockers. The D44 front diff is also better suited for 35's vs D30 front on Sport and Sahara.
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Unread 10-27-2013, 05:56 AM   #10
spinlock
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The Rubi uses Rock-Trac which is manufactured by New Venture a manufacturing consortium of the Big 3 and is designed specifically to work with locking differentials. The Sport uses the Command-Trac a more general purpose transfer case was originally designed by New Process a division of Chrysler which is now part of New Venture.

There are numerous videos on YouTube explaining the details of most 4WD system known to man or at least Google ... and the Jeep website shows which model has which system
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Unread 10-27-2013, 08:42 AM   #11
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Aren't Rubicon and Sport transfer cases both NV241? Just with different gearing?

And I think 4.88s with a manual are too low for 35s and daily driving.

TruTracs are just nice limited slips, they don't lock like a Rubicon. Limited slips aren't worth that kind of money in a JK since they have the brake lock technology that works shockingly well.
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Unread 10-27-2013, 09:29 AM   #12
brianjw
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Quote:
Originally Posted by krawler510
Aren't Rubicon and Sport transfer cases both NV241? Just with different gearing?

And I think 4.88s with a manual are too low for 35s and daily driving.

TruTracs are just nice limited slips, they don't lock like a Rubicon. Limited slips aren't worth that kind of money in a JK since they have the brake lock technology that works shockingly well.
I think the rubicon is a 241OR, with a lower ratio and stronger case.

I wouldn't say 4.88 and manual are "way" too low in 35s. 4.56 would be equal to stock rubicon gearing so its just a little lower. Probably lower than necessary for most though.

One advantage to the Truetrac though is that the brake lock differential should make the Truetrac nearly lock up in difficult conditions, but work smoothly. But not quite like a locker still.
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Unread 10-27-2013, 10:20 AM   #13
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Quote:
Originally Posted by brianjw
One advantage to the Truetrac though is that the brake lock differential should make the Truetrac nearly lock up in difficult conditions, but work smoothly. But not quite like a locker still.
I'm sure it would be very effective but they are expensive. I'd just vote real locker for off roading.

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Unread 10-27-2013, 11:55 AM   #14
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Quote:
Originally Posted by krawler510 View Post
I'm sure it would be very effective but they are expensive. I'd just vote real locker for off roading.

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Agree with this. There is no substitute for a 'real' locker when wheeling. A limited slip will help you in snow/ice/rain, but will not help much when wheeling rocks compared to a locker.

Besides, the factory LSD in the Sport and Sahara don't work very well, pretty useless. The lockers in the Rubi on the other hand work very well.

Here's a good article on the different types of lockers:

http://www.fourwheeler.com/how-to/tr...cker-overview/

Click 'read full article' at the bottom of that page.
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