Transfer Case "tough" to shift in motion? (2H to 4H)

[Vtur]

2hi to 4hi up to 55mph.
4hi to 4lo trans in neutral and no more than a few mph.

Put some man power to it lol.

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[Janster]

When was the last time you tried to engage 4WD?

As they say…If you don’t use it, you lose it. Things will get stiff (kinda like my muscles & joints) if you don’t use them often enough to keep things ‘lubricated’.

 

[Badunit]

I can't shift from 2H to 4H until I slow down to nearly stopped. I've tried it in Drive and in Neutral, no difference either way. I've leaned on it pretty hard in my attempts but I'm afraid to put too much force on it when it should be slipping in easily. I don't use 4wd that often so it could be that. Maybe some day soon I'll spend some time shifting it in and out a bunch of times and see if it loosens up.

 

[Maverickxeo]

I can't shift from 2H to 4H until I slow down to nearly stopped. I've tried it in Drive and in Neutral, no difference either way. I've leaned on it pretty hard in my attempts but I'm afraid to put too much force on it when it should be slipping in easily. I don't use 4wd that often so it could be that. Maybe some day soon I'll spend some time shifting it in and out a bunch of times and see if it loosens up.

That's exactly my situation.

 

[Volt0]

Weird. Got anyone nearby that would let you do a short test drive with theirs? Dealership?

 

[Vtur]

For more leverage.

 

[Janster]

I can't shift from 2H to 4H until I slow down to nearly stopped. I've tried it in Drive and in Neutral, no difference either way. I've leaned on it pretty hard in my attempts but I'm afraid to put too much force on it when it should be slipping in easily. I don't use 4wd that often so it could be that. Maybe some day soon I'll spend some time shifting it in and out a bunch of times and see if it loosens up.

I know this sounds weird……

Sometimes turning the steering wheel ever so slightly or rocking the rig back-n-forth slightly …just enough to allow things to ‘line up’. At least try that to see if you get easier engagement.

Before 4Auto existed, I used to engage 4WD anytime during a hard rain while driving on the highway or straight roads. Drive for a few miles and back into 2wd again. I actually liked using 4hi in the hard rains…..felt sturdier.

 

[NC_Overland]

I know this sounds weird……

Sometimes turning the steering wheel ever so slightly or rocking the rig back-n-forth slightly …just enough to allow things to ‘line up’. At least try that to see if you get easier engagement.

Before 4Auto existed, I used to engage 4WD anytime during a hard rain while driving on the highway or straight roads. Drive for a few miles and back into 2wd again. I actually liked using 4hi in the hard rains…..felt sturdier.

Ive done it. I did it once when driving through a horrible storm with tornadoes around in E MO and another time in tropical storms in NC and FL. It does help and I don’t think it hurts anything when water is ponding on the roads like that.

 

[Maximus Gladius]

North - Wetaskiwin

Darn, I would have been over in a heartbeat if you lived in Calgary. Wetaskiwin is a bit north of me,.. you'll be ok. You have a dealership there that should be able to help you out. Probably a super simple fix.

 

[BearFootSam]

Now that it's cold (average 30⁰ and under lately) outside, shifting into 4h is a bit stiffer than in the past.
This is my first 4x4 that ISN'T push button, so, I'm still green to Jeep things haha

The jeep is an odd duck that straddles the line between ancient and modern. A lot of old trucks require a degree of manhandling to operate that feels as if you’re going to break something if you’re used to modern passenger vehicles in which every control is effortless. So the force required to operate the t-case lever might seem excessive but it’s totally fine. The key is to fully commit and yank it into position with authority. The trouble occurs when you hesitate and then get the grindy noises.

 

[DylanM]

Part of the reason why it takes more effort to shift from 2H to 4H while in motion is because the JT has a FAD.

In 2H the FAD is disconnected. What this means is the right outer axle shaft is not mechanically connected to the right inner axle shaft, ie, each one can (and will) spin independently of the other. As a result of the FAD being disconnected, when driving along in 2H what you have is the right outer axle shaft is spinning the same direction and speed as the right front wheel (because they're splined together), the front driveshaft is not spinning and consequently the front differential is not spinning, the left axle shaft is spinning in the same direction and at the same speed as the left front wheel (because they're splined together), and the right inner axle shaft is spinning the opposite direction but same speed as the left axle shaft due to the action of the spider gears inside the differential.

When you shift from 2H to 4H, the FAD actuator has to move a splined collar to engage the inner and outer axle shafts to lock them together, and the mode selector fork in the transfer case has to engage the splined mode collar with the t-case mainshaft, thereby locking the front and rear t-case outputs together. Doing this while the vehicle is in motion, the front driveshaft and differential inertia has to be overcome to accelerate them both up to speed to match the t-case mainshaft and the left front axle shaft, and the right inner axle shaft has to completely reverse its direction of spin so as to match that of the right outer axle shaft. Honestly, it's a bit of a surprise things shift as easily with minimal grinding as they do.

On previous 4wd iterations without a FAD like in the TJ and JK, the front driveline was always spinning at the correct speed to match the rear so it was very easy to get the t-case mode collar to engage while in motion. In my TJ you can literally shift back and forth between 2H and 4H while in motion using one finger.

But hey, supposedly using a FAD setup improves fuel mileage by a mile per gallon or two.

 

[Maverickxeo]

Part of the reason why it takes more effort to shift from 2H to 4H while in motion is because the JT has a FAD.

In 2H the FAD is disconnected. What this means is the right outer axle shaft is not mechanically connected to the right inner axle shaft, ie, each one can (and will) spin independently of the other. As a result of the FAD being disconnected, when driving along in 2H what you have is the right outer axle shaft is spinning the same direction and speed as the right front wheel (because they're splined together), the front driveshaft is not spinning and consequently the front differential is not spinning, the left axle shaft is spinning in the same direction and at the same speed as the left front wheel (because they're splined together), and the right inner axle shaft is spinning the opposite direction but same speed as the left axle shaft due to the action of the spider gears inside the differential.

When you shift from 2H to 4H, the FAD actuator has to move a splined collar to engage the inner and outer axle shafts to lock them together, and the mode selector fork in the transfer case has to engage the splined mode collar with the t-case mainshaft, thereby locking the front and rear t-case outputs together. Doing this while the vehicle is in motion, the front driveshaft and differential inertia has to be overcome to accelerate them both up to speed to match the t-case mainshaft and the left front axle shaft, and the right inner axle shaft has to completely reverse its direction of spin so as to match that of the right outer axle shaft. Honestly, it's a bit of a surprise things shift as easily with minimal grinding as they do.

On previous 4wd iterations without a FAD like in the TJ and JK, the front driveline was always spinning at the correct speed to match the rear so it was very easy to get the t-case mode collar to engage while in motion. In my TJ you can literally shift back and forth between 2H and 4H while in motion using one finger.

But hey, supposedly using a FAD setup improves fuel mileage by a mile per gallon or two.

That makes sense - my TJ shifts like butter (but I do have a cable shifter).

I've been testing out the transfer case again over the last few days - and I've been able to get it into 4WD at highway speeds - it takes a LOT of force, and it doesn't feel like it goes in all the way, but it does.

That said, I also notice that when the FAD is 'engaged' and I shift it out of 4wd and back a few seconds later, it goes in as easily as my TJ does - I somewhat suspected the FAD was the reason for the 'tough' shifts.

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