Ever had your Jeep drop out of 4LO spontaneously?

[Rubi SoHo]

So this happened to me in the summer, but wanted to see if anyone has had anything similar?

Was in Moab, lined up to show my wife and kids the Baby Lionsback. They’d never been off-road in this Jeep yet. Put her in 4LO and started up. About half way, we lost traction, then lost all forward momentum. Had to back down (skid backward really), terrified my wife. I was a bit spooked too because the jeep kept trying to slide sideways which would have lead to a rollover, but we got down without any accident fortunately.

Realized I’d somehow ended up with the transfer case in Neutral. I’m guessing I just didn’t fully engage the thing somehow, and it popped out? But it felt like we were fully engaged and light on dash said 4LO, and I had the rear locker on. We made it ⅔ of the way to the top so we were definitely in 4LO at the start of the climb.

Would be lying if I said I didn’t have some loss of trust in the system now. I did spend the rest of the day in 4LO on a different trail without issues, but no sustained climbs were encountered so haven’t “recreated” the scenario that caused this in the first place.

Jeep operates flawlessly ever since.

Anyone think I may have an issue that needs to be looked into? Or just bad/luck coincidence?

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[Deleted member 59498]

No but my 2020 would pop out of 4Hi often when new and really hard to engage. No problem with new one.

 

[Jtclayton612]

When new I had it pop out of 4HI a couple times. It didn’t want to engage unless it was really in there, also busted my knuckles a couple times going back to 2HI. After I broke it in by shifting back and forth a few times I haven’t had any problems.

 

[Dan M.]

I've had it pop out the first few times I used it. I think the lever doesn't fully go into 4Lo until you use it a few times.

 

[jeepoch]

@Rubi SoHo,

Many people have difficulty with the 4Hi to 4Lo shifting. Recall in 4Hi you're using the same gearing as in 2Hi. There is no gear change, just the engagement of the front drive shaft. So that's why you can shift into 4Hi at speed.

Going to 4Lo (or back into 4Hi), you are actually engaging (or disengaging) the lower 4 to 1 gear set. However, this gear selection is clutchless. That means the teeth and cogs got to mesh mechanically before the gear change is applied. That's also why you have to do this at low speed (but rarely ever stopped).

In order for this meshing to occur, the input shaft rotation rate from the transmission) must much the rotation rate of the output shaft speed of the drive shaft to the axles (and indirectly via the differentials to the wheels). This is exactly why it requires a low velocity, either forward or backward of the vehicle to make this shift occur easily.

When stopped and even when in transmission neutral, the alignment of the teeth to the cogs of the new gear set may not line up exactly. And when not, the gear change is very difficult if not impossible no matter how hard you apply force to the transfer case lever. Only when the teeth can truly mesh can the shift occur and the new gearing now be fully engaged.

It is of course possible to just partially engage the lower gear and this is likely what happened to you. In that case, the shift lever may have 'felt' like it was fully pulled back all the way into the 4Lo position but not really. From your reference, it may have seemed 'in-gear' but rather have just been partially seated.

This allowed you to move, up until the torque became high enough to start shaving the teeth and dropping out of gear.

Remember, this is a manual no clutch process. The trick is to just move your rig slow enough to naturally mate with the new gearing. When performed properly, each gear change should be smooth and seamless. If not, then some grinding will occur and the edges of the gear teeth will become 'rounded'.

Some people continue to force their transfer case into gear saying it just needs to be broken in. What's actually occuring is the teeth are being gound down, shaved and rounded so that it's easier to mesh.

The down side is that with rounded teeth it's also much easier to fall out of gear. Plus all the metal shavings now in the transfer case fluid.

So the secret is to never 'force' a gear change. (Never.) If the shift isn't smooth and seamless, the natural meshing of the teeth isn't happening. With practice, you'll gain confidence in meshing the gear shifts. Again it's all about invoking a real slow (< 3pmh) roll before shifting the lever. But then making the shift with little to no force. The 4Lo lever position will go all the way back nearly effortlessly.

One should never have to 'break-in' a transfer case. The gearing is designed to mesh, but only when naturally aligned.

Hope this helps.
Jay

 

[Shibadog]

That’s scary. I’ve never had that happen on any 4wd I’ve had. I’m betting you weren’t fully “in” 4 lo. New shifters on these are a PITA. Be careful out there.

 

[BDinTX]

With our first Wrangler I found a gravel road and practiced shifting in and out of 4Lo. I figured I didn’t want to be trying to learn it when I actually needed it. In our case, the transfer case shift cable wasn’t set correctly from the factory. It wouldn’t stay in 4Lo with power applied even with me HOLDING it in gear.

To resolve I had to take out the center console and adjust the shift cable.

Wrangler #2, I tested 4Lo on my test drive before signing on the dotted line.

@Rubi SoHo since yours went into, and stayed in 4Lo the rest of the day it likely was just an incomplete shift. Like @jeepoch described, you need to be rolling. Test it out a few times when you don’t have an audience. That can cause performance anxiety.

 

[Rubi SoHo]

Thanks guys, I figure everything is probably fine, but I’d be lying if I said it won’t be in the back of my mind for a while until I feel like I can trust it again.

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