Need a little help understanding 4WD response

[techteacher]

Was out with the JT for the first trail ride yesterday and it was a beast. I'm new at all of this and looking for a little help understanding what the Jeep was doing when I got it stuck in a mudhole.

Went into it and cruising along and then got caught up front and rear just sank into some ruts and felt like I was sitting on my belly. What I didn't understand was how the 4WD system was reacting. I gave it gas and I got nothing - no wheel spinning, no response. Watching the recovery video it was like my tires didn't start spinning until they got the little nudge of the recovery strap and then it just crawled itself right on out. Maybe I was just expecting wildly spinning tires and the Jeep is just smarter than me in that situation.

So, if you are about to run through a mudhole what are you turning on/off? 4hi/4lo? lockers locked/unlocked?

I feel like there is a Marisa Tomei simple My Cousin Vinny explanation here that I need.

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[MarineHawk]

It's strange that you couldn't get any spin from the tires, but I assume it's the traction control system overreacting. The more of these types of stories I read, the more I'm glad that I have lockers on mine (as do you). I assume that, if you had locked the axles, you would have gotten power to all four tires. This is because the TCS starts its mischief when one tire is spinning faster than the other tire on the same axle. That can't happen when you have the lockers engaged.

 

[ZTMAN]

What 4wd mode were you in when you were stuck?

 

[Mark Doiron]

Were you in low or high gear? Locked on which axles? Did you manually turn off the ESP system if in high (it automatically turns off in low)? If you were in high and didn't turn it off manually (full off--read your owner's manual; it's more than just a simple press of the switch), then the Jeep ESP system took control of the brakes and throttle. It wasn't expecting tire slippage and was trying to prevent that.

 

[bruno747]

If you were just in 4 high, it's very difficult to get all wheels spinning in thick muck. This platform just doesn't have enough low end oomf for that.

In 4 low locked, granted they won't be *wildly* spinning, but they will be spinning.

If traction control was activating your Jeep should have had a wild exhaust note as it defuels and pulls timing out to drop power. Might be hard to hear on factory exhaust though.

 

[PyrPatriot]

It's strange that you couldn't get any spin from the tires, but I assume it's the traction control system overreacting. The more of these types of stories I read, the more I'm glad that I have lockers on mine (as do you). I assume that, if you had locked the axles, you would have gotten power to all four tires. This is because the TCS starts its mischief when one tire is spinning faster than the other tire on the same axle. That can't happen when you have the lockers engaged.

But isnt traction control disabled in 4L?

 

[techteacher]

But isnt traction control disabled in 4L?

That's what I thought - it gives a warning when switching into 4lo. I was in 4lo at the time with no lockers on.

 

[Mark Doiron]

But isnt traction control disabled in 4L?

Yes. It's all part of turning off the ESP system, which can be done manually in 4WD-high, and automatically in 4WD-low. And in high there are two modes of off, what they call full and partial. I encourage anyone who thinks pressing the ESP switch to off turns it off to read their owner's manual. There's more to it than that.

 

[Mark Doiron]

That's what I thought - it gives a warning when switching into 4lo. I was in 4lo at the time with no lockers on.

The lockers ensure that both tires on that axle spin at the same speed. Without it, if one tire starts to slip, brake locking differential tries to compensate by applying the brake to that spinning tire, slowing it down and allowing the differential to send power back over to the tire that's not spinning. This is probably what you observed when you saw no tires spinning. The locker, however, keeps both tires spinning at the same speed. A locked front axle makes steering tough, and (from my experience) can lead to damage to the power steering pump (if you turn too hard too much, the fluid overheats and causes the vanes in the pump to deform--it sucks to drive home from an adventure without power steering). Use the front locker with caution. However, it probably would have been a good idea to at least have the rear axle locked.

 

[ShadowsPapa]

Go to the 4wheel drive screen and it will show you what's going on to some extent.
Obviously these guys know their poop (can we say that here?) so little to add other than agree - and mention the screen as it should show some helpful information.
I like the advice given to go to 4L if not there already, locked that puppy - then you would be turning wheels because there's no place to lose the torque to that way.

 

[WXman]

Bottom line is that in 4-low if you get on the throttle pretty good it'll spin and throw mud everywhere. If you're saying that yours didn't do that, then there is an issue with it.

In 4-high if you hold the TCS button long enough it'll also disable traction control in that mode.

 

[MarineHawk]

But isnt traction control disabled in 4L?

No!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! It's only in a "reduced mode."

Read the manual.

“BLD may be enabled even if TCS and ESC are in a reduced mode.”

Without the lockers, the Jeep tries successfully to stop wheels from spinning even in 4WL “even if TCS and ESC are in a reduced mode.”

Read this thread’ read your manual: https://www.jeepgladiatorforum.com/forum/threads/question-about-traction-control.25038/

 

[MarineHawk]

The lockers ensure that both tires on that axle spin at the same speed. Without it, if one tire starts to slip, brake locking differential tries to compensate by applying the brake to that spinning tire, slowing it down and allowing the differential to send power back over to the tire that's not spinning. This is probably what you observed when you saw no tires spinning. The locker, however, keeps both tires spinning at the same speed. A locked front axle makes steering tough, and (from my experience) can lead to damage to the power steering pump (if you turn too hard too much, the fluid overheats and causes the vanes in the pump to deform--it sucks to drive home from an adventure without power steering). Use the front locker with caution. However, it probably would have been a good idea to at least have the rear axle locked.

Just to be clear, locking the front axle without crazy sharp turns on hard surfaces can significantly add to your traction for reasonably short stretches. He was just trying to go straight through a mud pit, and the TCS was stopping him from doing it. Going through mud with the front locked won't damage the steering pump.

 

[Mark Doiron]

Just to be clear, locking the front axle without crazy sharp turns on hard surfaces can significantly add to your traction for reasonably short stretches. He was just trying to go straight through a mud pit, and the TCS was stopping him from doing it. Going through mud with the front locked won't damage the steering pump.

The time mine happened, it was a mudhole on a trail. There was a sharp turn as you exited the mudhole. I have no idea what OP's exact situation was. But, hope that sharing my experience might save him (and others reading this) the expense and misery I suffered.

 

[ShadowsPapa]

The time mine happened, it was a mudhole on a trail. There was a sharp turn as you exited the mudhole. I have no idea what OP's exact situation was. But, hope that sharing my experience might save him (and others reading this) the expense and misery I suffered.

I think we can sum it up with "use the lockers, but if you have to turn more than very slightly, unlock the front axle" - sound about right?
Because the inner wheel of a turn has to go slower than the outer wheel of a turn - locking prevents that but if the turn is very gradual AND you are on slick surface, no harm.
Just unlock before making as sharp turn especially on a solid surface.

Don't need to own a Jeep - it's why we don't put locking or limited slip differentials in the front of Eagles.

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