4WD or Not?

[J-Frame]

All Rubicons have a 4:1 Rock Trac.

Not sure when they started offering but mine is an earlier 21 build and has it. Maybe you missed it on the option sheet?

Possibly, or just dealer didn't know any better. The only Rubicon I've seen it on is a 392. Maybe its a Southern thing, lol!

Sponsored

 

[Dyolfknip74]

Possibly, or just dealer didn't know any better. The only Rubicon I've seen it on is a 392. Maybe its a Southern thing, lol!

392 is a little different, it has no "2wd" either. It can be activated via Tazer though.

Nope, there is lots of them.
In saying all this, I wish I didn't have it. I prefer to know when I'm in 4wd. Tipping the tcase lever isn't a big deal although I am happy it's there for my spouse when she's driving.
I also had specific "Svc4wd" that were related to it as well. PIA.

 

[J0E]

Nobody's suggesting you mash the brakes. Just put it in 1st in 4H if there is no other reason to be in 4L and gently apply braking as necessary. Engine braking for the majority of the effort with brakes gently applied to make up any deficit.

1st isn't low enough, that's a solid reason. Off road you should be in 4 Low rather than 1st being too high.

Well, I should have mentioned I keep it in manual, usually 1st gear. Still too fast.

 

[dcmdon]

dcmdon,
I'm not sure if you are asking me (The OP), or someone responding. I haven't said anything about a tire losing traction at all. My question really revolves around overheating the brakes by riding them or using 4Lo and the gear reduction offered by the 4:1 case in my Rubicon to maintain a slow enough speed on badly worn, rutted up Forest Service roads we frequent. Wifey has back issues, and I have pretty severe shoulder issues, so the head-toss is a problem, and sometimes we just want to go slow and see the view. The 2Hi range, even locked in manual and 1st gear is frequently too fast. And at least in my opinion, the engine braking on the 2.0Turbo is pretty non-existent unless I'm running high revs.

J-Frame

You can't overheat brakes in any kind of rock crawling. The amount of energy you are putting into them is a tiny TINY fraction of the energy of a stop from 70 mph. Its not even close.

The reality is that the hardest you will work your engine, brakes, or transmission is on the road. Driving along at 70 mph the engine has to put out somewhere in the area of 80 hp just to maintain speed.

Tooling along on the trail the motor is putting out a small fraction of that. And don't forget that the kinetic energy that the brakes have to turn into heat varies as a square function.

That means that your truck has 16 times as much energy the brakes need to absorb at 80 mph as it does at 20 mph.

 

[unsavory]

I don't think you are correct, particularly with the 4:1 RockTrac transfer case. Perhaps they used to be, or maybe without the 4:1. Someone will check the Jeep builder and find out I bet.

My late model 2022 JLUR has the 4:1 Rock Track Heavy Duty Full Time 4wd option. It was a $800 add-on.

This system comes with CV joints in the front, instead of U-Joints.

The transfer case has positions for 2H, 4H-Auto, 4H-Full Time, and 4L.

 

[J-Frame]

An elucidating thread. We will probably go on a short afternoon ride today on a local FS section that is pretty rough. I’ll air down to 20 psi, and play with 2Hi/brakes vs 4Lo/gearing and see which I’m more comfortable with.

Continuing the education, on this type of rutted roads (not rock-crawling) what is everyone’s experience with sway bar disconnect? Any improvement in ride and handling or a waste of time?

J-Frame

 

[JayJay]

what is everyone’s experience with sway bar disconnect? Any improvement in ride and handling or a waste of time?

Hi Joseph, I have the sway bar disconnected most of the time when I'm on forest service roads. It smooths out the side-to-side shock when hitting potholes and rocks.

 

[J-Frame]

Hi Joseph, I have the sway bar disconnected most of the time when I'm on forest service roads. It smooths out the side-to-side shock when hitting potholes and rocks.

And that is part two of what I’m looking for! Wifey is not a fan of head-slap! Much easier on the nut holding the steering wheel to deal with it. Will be trying all the Rubicon goodies out later today.

None of my other three Jeeps have been Rubicon’s, and I have sort of ignored the gizmos on my ‘21 Rubi, never needed them, never had them. I have to say I am no longer one of those that thinks the Sport is “the same thing” as a Rubicon.

J-Frame

 

[Steph1]

It is a good idea to use it when you safely can, even if it’s just to make gears turn and work.

As for your opening comment, if people would only modify for ‘’needed’’ upgrades, only a few guys here would be driving modified Jeeps. The vast majority modify for looks, as all Jeep models are very capable and way more sufficient than their owners need.

 

[JayJay]

And that is part two of what I’m looking for! Wifey is not a fan of head-slap! Much easier on the nut holding the steering wheel to deal with it. Will be trying all the Rubicon goodies out later today.

Airing down as you mentioned will also help with the "head slap". Between that and disconnecting the sway bar I think that you'll see a noticeable improvement.

BTW, we love the Roan Mountain area. We come up every year for the Rhododendron Festival at the state park. Mitchelle shops the arts and crafts and I listen to the music.

 

[jeepoch]

Joseph,

I off-road a lot in my 2019 2Door 3.6L Sport. No fancy anything in terms of transfer case options on my rig. No lower differential gears, lockers, duck buttons or any of the cool things available to you. However, my fun factor is still incredibly high when wheeling here in my home state of Colorado.

I find that lifted on 35's with manually disconnected sway bars along with the ZF8-speed transmission 'Autostick' allows me to go nearly anywhere here in the mountains I care to meander. Any day at or above treeline is certainly why I love this thing. Truthfully, driving around the flat lands along the Front Range is also a blast. This Wrangler is my daily driver and the best vehicle I've ever owned. I've owned it for exactly three years now, have 50K miles on the odometer and a good fraction of that has been off-road. Maybe 25% or more.

I am nearly always in either 4Hi or 4Lo when not on pavement. With the Sport's standard 2.72 transfer case and 3.45 gear ratio (much taller than your 4.0 and 4.10's respectively), I find my compromise in which 4wd gearing selection is mostly in anticipated my top speed. Since it's pretty easy to achieve 7th or 8th at just 20-25mph in 4Lo, I tend towards 4Hi only on well maintained county roads. However, I'll never shy away from going low whenever the conditions warrant. Any steep grade (either up or down) and 4Lo is generally a reflex decision. Having good engine braking available is typically never an after thought for me. It's a nice advantage to have all the tools at my disposal when within any serious off-road situation. Needing to switch to 4Lo (on the fly) when it's not already there is never in my (or your) best interest. Never. It's always best to think ahead.

So it basically comes down to this; can you trade top traveling speed for the potential of requiring significant (useful) engine braking at very low velocities? In 4Hi, 1st gear can be maintained (without red-lining) up to about 10mph. Way too fast for most off-road situations. So, anticipating travelling at a top threshold velocity of 15 to 20mph anywhere off-pavement is how I routinely use the 4wd transfer case lever.

Mountain trails, steep grades, inclement weather or any other mitigating factor nearly always finds me selecting 4Lo (along with a lighter than normal foot on the throttle). Open diffs also mean that I simply can't just muscle my way through the really tough stuff like you locker junkies can. Traction is absolutely my best friend. No slipping (spinning) of any wheels for me.

Furthermore, the Hill Decent Control (HDC) feature is by far the best thing since sliced bread when the situation arises. Needing to only manually brake going downhill is such a comfortable safety improvement. In fact one I would sorely miss if this feature wasn't available. Controlling your decent velocity in 0.7mph increments is just such a pleasure in the really extreme stuff. Not needing to ride the brakes in any safety critical condition is for me, priceless. If you don't know how HDC works or how to use it, figure it out and practice. It really is that good. Not that difficult to use. I love it.

However in snow, especially in the deeper stuff, I find that 4Hi using Traction Control (TC) is sometimes way superior. Regardless, every JL independent of trim, all support Brake Lock Differential (BLD). This automatically applies braking action to any single slipping wheel whenever any axle is not 'locked'. Recall, a locked axle mechanically connects both wheels on the same axle together. So both will spin at the same rate independent of applied torque. So with lockers any one wheel (of all four) that 'grips' will maintain forward momentum. When unlocked with open diffs, at least two wheels on the same axle must 'grip' to keep moving. Also recall that with an open differential (or unlocked axle), the slipping wheel gets the most delivered torque. So the slipping wheel only tends to slip even more. By automatically applying braking action to just that slipping wheel, then the other wheel gets more of the applied torque. In other words, BLD is a cheap semi-slip pseudo locker.

Another technical gotcha is that TC is generally only applied when driving 'straight'. It coordinates the braking action in concert on all four wheels on both axles to try and maintain traction and forward momentum. But both features [TC and BLD] really do help maintain traction in the most slippery of conditions. Yet interestingly, TC is completely disabled in 4Lo but BLD is not. Brake Lock Differential is always active on any wheel spinning at a faster rate than the other on the same axle. So even if you choose 4Lo (without lockers) the JL will still try it's best to keep you moving. So even us JL Sport pilots have a tremendous off-road advantage over every other Jeep model without lockers. That is also why the JL Rubicons can tackle quite a lot of the really tough stuff without the need to engage it's lockers. But as the old cliche goes, it's always better to have the capability available when needed than not having it when you don't.

In summary, there are always dynamic conditions which require some forward thinking when selecting the most appropriate 4wd mode. But by far (for me), in good conditions, I generally have a lot more fun in 4Lo at low speed when adventuring through the high altitude mountain passes that I call my back yard. Smelling the scent of Douglas Fur and Forest Pine is never something I tend to travel quickly through. I really, really enjoy getting off the beaten path and finding a panoramic vista that only people with a horse, good hiking boots or a Jeep can get to.

Have fun, stay safe, Jeep on...
Jay

 

[J-Frame]

Airing down as you mentioned will also help with the "head slap". Between that and disconnecting the sway bar I think that you'll see a noticeable improvement.

BTW, we love the Roan Mountain area. We come up every year for the Rhododendron Festival at the state park. Mitchelle shops the arts and crafts and I listen to the music.

Come see me next time you are up here. I own Bob’s Dairyland in Roan Mtn.

 

[J-Frame]

Joseph,

I off-road a lot in my 2019 2Door 3.6L Sport. No fancy anything in terms of transfer case options on my rig. No lower differential gears, lockers, duck buttons or any of the cool things available to you. However, my fun factor is still incredibly high when wheeling here in my home state of Colorado.

I find that lifted on 35's with manually disconnected sway bars along with the ZF8-speed transmission 'Autostick' allows me to go nearly anywhere here in the mountains I care to meander. Any day at or above treeline is certainly why I love this thing. Truthfully, driving around the flat lands along the Front Range is also a blast. This Wrangler is my daily driver and the best vehicle I've ever owned. I've owned it for exactly three years now, have 50K miles on the odometer and a good fraction of that has been off-road. Maybe 25% or more.

I am nearly always in either 4Hi or 4Lo when not on pavement. With the Sport's standard 2.72 transfer case and 3.45 gear ratio (much taller than your 4.0 and 4.10's respectively), I find my compromise in which 4wd gearing selection is mostly in anticipated my top speed. Since it's pretty easy to achieve 7th or 8th at just 20-25mph in 4Lo, I tend towards 4Hi only on well maintained county roads. However, I'll never shy away from going low whenever the conditions warrant. Any steep grade (either up or down) and 4Lo is generally a reflex decision. Having good engine braking available is typically never an after thought for me. It's a nice advantage to have all the tools at my disposal when within any serious off-road situation. Needing to switch to 4Lo (on the fly) when it's not already there is never in my (or your) best interest. Never. It's always best to think ahead.

So it basically comes down to this; can you trade top traveling speed for the potential of requiring significant (useful) engine braking at very low velocities? In 4Hi, 1st gear can be maintained (without red-lining) up to about 10mph. Way too fast for most off-road situations. So, anticipating travelling at a top threshold velocity of 15 to 20mph anywhere off-pavement is how I routinely use the 4wd transfer case lever.

Mountain trails, steep grades, inclement weather or any other mitigating factor nearly always finds me selecting 4Lo (along with a lighter than normal foot on the throttle). Open diffs also mean that I simply can't just muscle my way through the really tough stuff like you locker junkies can. Traction is absolutely my best friend. No slipping (spinning) of any wheels for me.

Furthermore, the Hill Decent Control (HDC) feature is by far the best thing since sliced bread when the situation arises. Needing to only manually brake going downhill is such a comfortable safety improvement. In fact one I would sorely miss if this feature wasn't available. Controlling your decent velocity in 0.7mph increments is just such a pleasure in the really extreme stuff. Not needing to ride the brakes in any safety critical condition is for me, priceless. If you don't know how HDC works or how to use it, figure it out and practice. It really is that good. Not that difficult to use. I love it.

However in snow, especially in the deeper stuff, I find that 4Hi using Traction Control (TC) is sometimes way superior. Regardless, every JL independent of trim, all support Brake Lock Differential (BLD). This automatically applies braking action to any single slipping wheel whenever any axle is not 'locked'. Recall, a locked axle mechanically connects both wheels on the same axle together. So both will spin at the same rate independent of applied torque. So with lockers any one wheel (of all four) that 'grips' will maintain forward momentum. When unlocked with open diffs, at least two wheels on the same axle must 'grip' to keep moving. Also recall that with an open differential (or unlocked axle), the slipping wheel gets the most delivered torque. So the slipping wheel only tends to slip even more. By automatically applying braking action to just that slipping wheel, then the other wheel gets more of the applied torque. In other words, BLD is a cheap semi-slip pseudo locker.

Another technical gotcha is that TC is generally only applied when driving 'straight'. It coordinates the braking action in concert on all four wheels on both axles to try and maintain traction and forward momentum. But both features [TC and BLD] really do help maintain traction in the most slippery of conditions. Yet interestingly, TC is completely disabled in 4Lo but BLD is not. Brake Lock Differential is always active on any wheel spinning at a faster rate than the other on the same axle. So even if you choose 4Lo (without lockers) the JL will still try it's best to keep you moving. So even us JL Sport pilots have a tremendous off-road advantage over every other Jeep model without lockers. That is also why the JL Rubicons can tackle quite a lot of the really tough stuff without the need to engage it's lockers. But as the old cliche goes, it's always better to have the capability available when needed than not having it when you don't.

In summary, there are always dynamic conditions which require some forward thinking when selecting the most appropriate 4wd mode. But by far (for me), in good conditions, I generally have a lot more fun in 4Lo at low speed when adventuring through the high altitude mountain passes that I call my back yard. Smelling the scent of Douglas Fur and Forest Pine is never something I tend to travel quickly through. I really, really enjoy getting off the beaten path and finding a panoramic vista that only people with a horse, good hiking boots or a Jeep can get to.

Have fun, stay safe, Jeep on...
Jay

Jay,
That is an excellent response!

Wifey and I just got back in from our Sunday Expedition and we had an excellent trip. I played with airing down to 25 psi from 30 last weekend, and we covered a familiar FS road about 15 miles long. We did hit an off-side trail we have never done before.

After airing down, I watched my speed, holding in 1st, we were at about 15-16 mph and without braking we were too fast for wifey’s picture taking, leaf-looking. Dropping into 4LO and using the autostick I ended up in 3rd/4th and about 6-10 mph without touching the brakes at all. I did use the “Off-road +” button, but did not disconnect the sway bar.

The head-slap was reduced considerably at 25 psi. Will drop to 20 psi next trip. And may try the sway-bar disconnect as well. Not trying too many things at one time. All in all, a wonderful trip, with good results playing with the Jeep and trying new things.

Thanks!
J-Frame

 

[J-Frame]

@jeepoch So you are not feeling any loss of power going to the 35’s with the stock gears? I am considering 35’s when I get around to new tires, with the 4.10’s and the turbo I don’t think I’ll really feel a dropoff in performance, I see 8th gear all the time now.

 

[jeepoch]

@jeepoch So you are not feeling any loss of power going to the 35’s with the stock gears? I am considering 35’s when I get around to new tires, with the 4.10’s and the turbo I don’t think I’ll really feel a dropoff in performance, I see 8th gear all the time now.

Joseph,

Sure, there is some noticeable drop in takeoff power when compared directly to stock. However, I bought a Jeep not a Ferrari. My take off acceleration on 35s still give me more than enough power to attain anything I may want or need to do with my Wrangler. Racing a Porsche is something I'd likely never consider.

For a true driving purist, the 3.45 differential gears is certainly not optimum but the 8-speed transmission handles the 35's almost as if it were designed for them. I had fully believed a regearing was in the cards and almost a forgone necessity. Yet, after giving it some time to experience this setup I've decided that leaving it alone has been perfectly fine (for me). But I'm no lead foot. I'm pretty happy with the 22-23mpg I can routinely achieve driving around the greater metro Denver area, which includes some of it's surrounding foothills. Even with the 3.6L v6. So leaving the stock gearing has had it advantages.

Also, many people love running on under inflated tires for the 'ride' feel. On trail this is of course desirable. I typically air down to 15psi any time when off-road (even casually). But on road, these 35x12.5x17 Duratracs get pumped up to 40psi. That's the pressure just slightly over the best chalk test of 38psi.

Sure this ride is not as 'mushy' but certainly helps with the better mileage and overall tread wear. Did I mention this is a Jeep and not some boring Prius?

I love my JL Sport. Off road it keeps me on my A game (without lockers), but it is also so much more accommodating on-road due to the taller gears.

But that's just me. I'm certain that there are hundreds of Jeepers that will tell me I'm all wet behind the ears for loving this setup. That's fine. That's the beauty of these things. Mod it the way it makes you happy. Mine puts a smile on my face every time I'm near it but especially when I'm out wheeling in it.

Go have fun. These things rock.
Jay

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