Gladiator crabs on 4WD Hi

[u-joint]

...2 u-joints...

There's only one u-joint around here.

Sponsored

 

[CerOf]

This isn't a differential problem, it's not a locker or LSD problem, it's a front axle issue.

It’s the front drive shaft being locked to the rear drive shaft with the longer wheel base means the front travels quite a bit different path/distance in a turn compared to the rear.

 

[CerOf]

Here’s a good article on it.
http://www.4x4abc.com/4WD101/def_turnpart.html

 

[Jeeperjamie]

Late to the game but mine does it as well, turning traction control off does make the feel less when turning. I already knew from it happening in my JKU that it would do it but you can feel it more in the JT. I found the same thing in the JKU that turning traction control off did the same thing. Also I also shift in and out of 4hi and to 2hi when driving, depending on the speed at which I'm turning. It freaks the wife out when she's driven them in the snow with 4hi on, she always thinks somethings wrong with the jeep.

 

[ricky0018]

Also late to the game but glad I saw this. First time Jeep owner and first winter in the Jeep for that matter. Had to switch to 4hi here in Illinois (which wasn't super intuitive in my opinion) and it was jerking like crazy on tight turns. Glad to hear that's normal but that doesn't mean I like it. Overall the Jeep has done really well in winter conditions though so I can't complain too much.

 

[ShadowsPapa]

From one of my college books on drive trains, drive shafts, locating vibrations and so on - look at the RPM variations on the output end. That shaft is switching from 850-1150 each revolution - and back. Do that on both front wheels and it feels like it's trying to walk, surging.
Doesn't 30 degrees sort of match the turning angle when you go into a parking lot, parking space or driveway?
The front axles aren't turning nearly that fast but look at the ratio and drop that down to 10 rpm at the inner shaft - it's still wanting to go from 10 down to 8.5 rpm then back up to 11.5 rpm.

At an angle of only 10 degrees (which isn't all that much) here's the change in rotational velocity minimum and maximum - at only 10 degrees angle and a rotational speed of 250 rpm on the input side, the output (or wheel side) varies 4 rpm each way - enough to cause a wheel to want to "jump":

This is why drive shafts have two joints phased a certain way - to eleminate that change in angular velocity at the far end - the speed the shaft up at the front joint and the rear joint slows it back down, when the front joint slows the driveshaft down, the rear joint speeds it back up so the input speed or velocity matches the output at the far end even though the driveshaft itself is speeding and slowing the whole time.

For evidence that CV joints don't have such issues, I can relate to my experience with Eagles. They have CV (Constant Velocity) joints at the front axles. Think about the term - constant velocity. Why are they used? To get rid of that jumping on vehicle where torque is always applied to the front axles, especially on turns.
As far as the transfer case locking the front and rear together - not really the issue, otherwise you'd have such jumping even with CV joints. You do not.
And to anticipate "but the Eagle transfer case isn't a part time.................... well, maybe not from the factory but hundreds of us have put in Jeep transfer cases to mix things up a bit, especially when that viscous coupling blows in the t-case. You then have the front and rear outputs locked just like the JT has - but have CV joints and no jumping in 4x4 mode (but STILL it's part time so you do not want to drive it on dry pavement in 4 wheel drive mode)

You are applying some hefty torque to those front axles, the more you turn the wheels, the higher the angular velocity change is. At only 10 degrees you have a pretty fair change. Turn it tighter and you can see some really large RPM changes if you do the math, enough to make the truck "jerky".

For those of you who have "flex sockets" in your tool box, you've probably noticed you can use them fairly easily if you don't have too much angle on them but get much past 10 or 15 degrees and it's almost impossible to turn that bolt or nut. It's a similar thing - this type of joint doesn't like tight turns especially under high torque.
It's ok when in coast mode or with little to no torque, and fine when you have it in 2 wheel drive as the inner shafts can speed up and slow down all they want, under no load.
Force them to try to keep up under load, under heavy torque (and it's worse with the transfer case locking the front and rear together) and they get a bit jumpy.

 

[willhonkforparts]

So I’m in Colorado Springs and my neighborhood is still snow packed after the supposed storm, I put my Gladiator Rubicon on 4hi and it feels like it’s crab walking when turning on snow packed roads. Is this normal? I had a 2 door JL Rubicon and I didn’t feel it crabbed at all.

That's just what u-joint axle shafts feel like in 4wd. I have had RCV shafts in my JKU for about 5 years now, and had completely forgotten how herky jerky the u-joints are, even in low grip situations.

 

[Elff]

I was playing around the snow the other day and ran into this exact situation.
I was really surprised how different it was from my little 2dr TJ.
But,
punching it in 2wd in snow with the wheel cranked is Fun as F@WK!!!!

The JT can do figure 8s with really nice control.

 

[ShadowsPapa]

I was playing around the snow the other day and ran into this exact situation.
I was really surprised how different it was from my little 2dr TJ.
But,
punching it in 2wd in snow with the wheel cranked is Fun as F@WK!!!!

The JT can do figure 8s with really nice control.

I used to take my AMX out into the empty Sears parking lot years ago after one our storms and do donuts, figure 8s, get it sliding and just let 'er rip. Besides fun, I gained insight on how to make it do what I wanted to do so on the street I had far better control and never had any troubles in the winter, snow or ice or both.

We've not had any good lasting snows like that in a long time. We get snows, but it's different in recent years (and I have few reasons to go anywhere since retirement, and the world has changed around here)

 

[Elff]

It is definitely good practice so you learn the capabilities of the vehicle before you get in over your head in bad weather on the street.

 

[Deleted member 23202]

It may be as simple as your axles not being centered under the truck.
Or that your toe alignment is off.
Or, if you have adjustable control arms, they may be off.

 

[ShadowsPapa]

Those things aren't going to have impact on what the OP is feeling.
Toe would have to be way off and would impact dry driving more than snow and ice or wet pavement. There's no reason for toe to be off enough to impact anything since lifts don't change toe (and he'd see feathering or scrubbing on the tires)
Control arms impact caster - not jumping when turning. Too much caster can cause wobble (if it's extreme) and too little can cause wander but won't make it jump when in 4 wheel drive making a turn. He'd also note either of those problems on the highway first.
Axle not being centered doesn't really impact much at all unless he's got a big lift and it's way off - and again, that would impact dry highway driving or turns and not the jumping feeling in snow or ice or slick.
Any of the above would be known on dry land. Axles being off-center don't seem to be a big problem on these unless they are way off or the owner is OCD.

 

[NC_Overland]

Will try that for sure, but don’t want to have too much fun in my neighborhood!

Looks like your questions are answered. I love Colorado Springs. The west side at least. What part of town? I lived there from ‘11-‘13. Old Colorado City.

 

[DrPlastic]

Just an off the cuff question....is there a CV joint conversion kit to convert the U-joint front axles to CV joints for those that do not have the 4-Auto transfer cases?

 

[Elff]

Yes
RCV Axle shafts
https://www.quadratec.com/p/readylift-suspension/ultimate-front-1-piece-cv-axles-jeep-wrangler-jl
Or the 35 spline version
https://www.quadratec.com/p/rcv-per...pline-front-1-piece-cv-axles-jeep-wrangler-jl

Sponsored