Confused Newb: Rubicon 4H/L and Lockers

[mgroeger]

Nothing abusive about that

Nope, I'm sure his T-Case looked good as new after doing that multiple times.

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[InMyImage]

While I haven't had a reason to mess with the JL yet, I would kick my TJ in and out of 4 hi at speeds as high as 80 mph. If the JL can't handle that kind of use (abuse?) I'm going to have a bad time.

Good to know that it won't cause the tranny to drop :p

 

[spurly]

On the TJ.... seems like it'd be pretty minimal because my front drive shaft would be spinning already. As long as I'm not in a turn the driveshafts should be going the same speed. But on a JL, with the FAD, my front drive shaft is not spinning. Right? I might be wrong on that. either way I'm going to do it at least once. I spend too much time crossing Wyoming (sunny day, snow drifts onto road, melts, sun goes down, now you have glare ice) it's just a matter of time. Maybe with traction and stability control I won't feel the need for it as much as I did in the TJ, but I'm sure there's going to be one I come on up and think "yeah that one looks bad" then reach down.

I've done it a few times around town while driving straight without any issues. It's gotten much easier to shift into 4H now. But I've often wondered on the drivetrains sequence when shifting to 4H. Say you're moving along at 30mph and need to shift to 4H. So, since the front driveshaft is not rotating in 2wd, does the FAD engage first (as soon as the transfer case shifter moves) or does the transfer case engage first?

 

[D60]

It's absolutely true vacuum FADs were problematic. Electric can be quite reliable, look to any GMT800

Ford sorta screwed the pooch with IWE's, although at least they default to lock and actually require vacuum to unlock.

For years it's been primarily electric transfer case motors that have been problematic (I've never owned a "pushbutton" that didn't screw me sooner or later), not so much axle disconnects

 

[D60]

Nope, I'm sure his T-Case looked good as new after doing that multiple times.

There's no reason why not, it's recognized as SOF for a reason

If you experience grinding when tugging on the lever (in any vehicle), stop. That's the sprocket for the front output not timing up. Otherwise, you're generally fine.

Front axles and/or IWE's simply won't lock until the splines line up, so they're pretty much self-policing

 

[xtopherm]

As far as driving on the street is concerned, 4 high is the same as 4 lock in the mitsubishi.

As far as the manual, Jeep basically took the lazy way in trying to explain it. You got the right idea. In 4 high or 4 low half of the power goes to the front axle and half to the rear axle. If a tire on either axle has no traction (ice, or in the the air are easy examples) then all of the power for that axle will go to the wheel without traction. Now in 4 high traction control can still be engaged so the brakes will try to slow the wheel in the air which, to put simply, moves power to the other wheel on that axle. It works well and I expect it to be very capable on the street in snow and ice. When you lock the axle it is a physical lock that engages between the two wheels on that axle and it forces them to turn at the same speed. When locked there is no way for the tire in the air to spin faster than the other tire on that same axle. This can be fun, but it's not a way that you want to drive on the street even if ice is present due to lack of control. Lockers could be handy if you find yourself stuck in deep snow on the street, but really lockers are for offroad use only (or parking lot shenanigans).

This answer should be pinned at the top. You absolutely nailed it.

In a Rubicon, 4-Hi gives you some electronic help - brake lock differential and electronic stability control and it monkeys with the throttle to cut power if there is big wheel spin. It is not quick to react, it requires a bit of throttle, it can overheat and it ultimately does not have the traction of true lockers. But it is a lot easier to steer compared to a Jeep with a front locker engaged.

4-Lo turns all the electronics off, but it allows you to lock the diffs manually and forces 25% of the power to each wheel. It is a rugged, reliable fully mechanical system (except for the locker actuators being electric - I just mean that it is straight gears and shafts from the crank to the wheel). The forced 25% power distribtion means that even if only one wheel has traction, it is enough to move the vehicle forward. And of course the other advantage to 4-Lo is more engine speed so you can crawl slower and still have plenty of torque.

It is great to have the option of trying both depending on what situation you are in, compared to say, one of those little Renegades or the like which just have the electronic option (and no low range Tcase).

 

[mgroeger]

This answer should be pinned at the top. You absolutely nailed it.

In a Rubicon, 4-Hi gives you some electronic help - brake lock differential and electronic stability control and it monkeys with the throttle to cut power if there is big wheel spin. It is not quick to react, it requires a bit of throttle, it can overheat and it ultimately does not have the traction of true lockers. But it is a lot easier to steer compared to a Jeep with a front locker engaged.

4-Lo turns all the electronics off, but it allows you to lock the diffs manually and forces 25% of the power to each wheel. It is a rugged, reliable fully mechanical system (except for the locker actuators being electric - I just mean that it is straight gears and shafts from the crank to the wheel). The forced 25% power distribtion means that even if only one wheel has traction, it is enough to move the vehicle forward. And of course the other advantage to 4-Lo is more engine speed so you can crawl slower and still have plenty of torque.

It is great to have the option of trying both depending on what situation you are in, compared to say, one of those little Renegades or the like which just have the electronic option (and no low range Tcase).

The only thing I would add is that the BLD does work in 4LO. Stability control is disabled when 4LO is engaged but the BLD remains active. I watched it in action this past weekend while we were wheeling.

 

[stylett9]

question, I'm trying to make sense of all the different awd/4wd/full time 4wd/full time awd... this all started with the 2021 discussions.

Am I correct in understanding that being in 4H, or 4L, is the equivalent to a center locking diff?
and because of this, that's the primary difference between a "full time awd, full time 4wd"? with Full time AWD/4wd, the vehicle is sending power to any one of the given four wheels at a time. But with pre-2021 rubicons, the reason you can't just leave it in 4H and think it's the same is because it's the equivalent to center lock? and I apologize, i do realize I just sort of talked in circle.

 

[mgroeger]

question, I'm trying to make sense of all the different awd/4wd/full time 4wd/full time awd... this all started with the 2021 discussions.

Am I correct in understanding that being in 4H, or 4L, is the equivalent to a center locking diff?
and because of this, that's the primary difference between a "full time awd, full time 4wd"? with Full time AWD/4wd, the vehicle is sending power to any one of the given four wheels at a time. But with pre-2021 rubicons, the reason you can't just leave it in 4H and think it's the same is because it's the equivalent to center lock? and I apologize, i do realize I just sort of talked in circle.

AWD is when power is being given to both front and rear axles all the time. It will never give it to all of the four wheels at any given time, it will only send to one of the fronts and one of the rears. In that regard the term "Four wheel drive" is very misleading since you are only ever turning one drive wheel on a given axle.
So that covers your AWD/Full time 4WD scenario and what is allowing this to happen is the transfer case, not the diff.
Being in 4HI or 4LO will achieve the same thing, that is allowing each axle to have a wheel that is being powered. The difference is you NEVER want to be in 4HI or 4LO on DRY pavement because there is no ability for it to slip any given tire during turning which is when the inner and outer tires will rotate at diff speeds. An AWD system allows for that slippage which is why you can drive it ALL the time even on dry roads.
NEVER engage 4LO on anything other than dirt, sand, loose gravel, etc...
If you want to truly engage ALL four wheels you must LOCK your diffs and this can only be done on the Rubicon model (unless you have added after market lockers). When your diff (the round ball looking thing in the middle of your axle) is locked power is being given to BOTH tires on that axle. Typically you are only locking your diff when you are in 4LO and NEVER on dry or even wet pavement. The advantage of locking the diff comes into play in the off road world where you need all four tires to be putting effort in to getting you through an obstacle. This way if one tire is in the air the other tire on that axle can still grab and get you through. Once an obstacle is overcome there is no need to keep your locker on.

 

[stylett9]

AWD is when power is being given to both front and rear axles all the time. It will never give it to all of the four wheels at any given time, it will only send to one of the fronts and one of the rears. In that regard the term "Four wheel drive" is very misleading since you are only ever turning one drive wheel on a given axle.
So that covers your AWD/Full time 4WD scenario and what is allowing this to happen is the transfer case, not the diff.
Being in 4HI or 4LO will achieve the same thing, that is allowing each axle to have a wheel that is being powered. The difference is you NEVER want to be in 4HI or 4LO on DRY pavement because there is no ability for it to slip any given tire during turning which is when the inner and outer tires will rotate at diff speeds. An AWD system allows for that slippage which is why you can drive it ALL the time even on dry roads.
NEVER engage 4LO on anything other than dirt, sand, loose gravel, etc...
If you want to truly engage ALL four wheels you must LOCK your diffs and this can only be done on the Rubicon model (unless you have added after market lockers). When your diff (the round ball looking thing in the middle of your axle) is locked power is being given to BOTH tires on that axle. Typically you are only locking your diff when you are in 4LO and NEVER on dry or even wet pavement. The advantage of locking the diff comes into play in the off road world where you need all four tires to be putting effort in to getting you through an obstacle. This way if one tire is in the air the other tire on that axle can still grab and get you through. Once an obstacle is overcome there is no need to keep your locker on.

so does my analogy/understanding of center lock hold true? For example, when people talk about Land Cruisers having a Center lock (triple lock), this is because it locks up the front and rears to rotate at the same speed, thus not allowing slippage from front to back. Therefor the term center lock or triple lock only applies to vehicles with awd.

for vehicles equiped with 4H and 4L, being in either 4H or 4L is the exact same thing. right?

 

[mgroeger]

so does my analogy/understanding of center lock hold true? For example, when people talk about Land Cruisers having a Center lock (triple lock), this is because it locks up the front and rears to rotate at the same speed, thus not allowing slippage from front to back. Therefor the term center lock or triple lock only applies to vehicles with awd.

for vehicles equiped with 4H and 4L, being in either 4H or 4L is the exact same thing. right?

I don't speak Land Rover so I can't say as to what that means but your explanation sounds plausible.

In short, when you engage a transfer case in a traditional 4 wheel drive vehicle you are sending 50% power to front and 50% power to rear. HOWEVER it is only going to ONE wheel on each axle and it will go to the wheel facing the LEAST resistance.
If you want ALL wheels to turn with equal power you must use your lockers which will lock your differential thereby making the tires on any given axle turn together.

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