UZJ100 4x4, 4wd system explained

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Jody Highroller

Jody Highroller

Joined
Jan 6, 2013
Threads
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100
Location
North Alabama
I've been googling, searching, reading forums everywhere. I'm searching for some 4wd system data on the '99 UZJ100. I am having a difficult time understanding the operation, functionality, and capability of my vehicle. A diagram, a animated video, a stick drawing would be great. :hhmm:

The '98-99 is a little different than the '00-07, which I have found lots of data on. My 99 has the full time 4WD, lo- hi range, RR locker, and center diff button. But after seeing some videos I am concerned that my vehicle is not a "real 4x4". I guess I am insecure about the IFS and no front locker. I am mostly concerned about using my vehicle to transport hunters where we typical go in a 97 V8 ZJ. The zj has taken 2 season of beatings and now its time for some PM. So now these guys are calling the LC for transport up. I think I can do it but I don't want to get stuck 5-10 miles up the incline either. I want to be sure my wheels are getting torque and how it gets it to the ground to spin the tires.

Operation: Right now, I would approach the mountain, stop the vehicle and pull it into Low. If it got rougher I press the center diff button. Roughest terrain I would finally turn on RR Lock.

Also, is my 99 UZJ as capable as a jeep ZJ grand Cherokee V8 with the solid axles and does that only affect articulation?
 
Also, is my 99 UZJ as capable as a jeep ZJ grand Cherokee V8 with the solid axles and does that only affect articulation? (Quote)

Does your 99 LC have the auto adjustable suspension?

How many adults and how much gear total will be traveling with? Three good size guys in the rear seats with gear will lower the rear down quite a bit. You will need to worry more for this as you might scrape the spare tire/hitch/bumper. This can cause one to get hung up as I did two times.
This was an issue with my LC, now that I have the rear coil spring airbags in, it's been great.

My opinion I say yes. My 1998 with rear locker is more capable than most of the other stock 4X4 trucks and jeeps that caravan with. This year I have done over twenty off-road trips in very harsh rocky muddy washed out up/down hill conditions. Haven't gotten stuck yet. My buddy's Jeep had to use his (he seems a little happy footed) winch a five times because of getting stuck, me zero.

If you pick the right line you should be fine.
 
The Mack said:
Does your 99 LC have the auto adjustable suspension?
Click to expand...

The LC doesn't have AHC, just the LX.

If you've got a factory rear locker you're doing well already. These trucks are very capable out of the factory and if you want to combat sagging springs you can go to an aftermarket setup for pretty cheap without lifting the vehicle too much. Airbags are another option more commonly used for towing.

Pick your lines carefully and your LC will do the rest of the work.
 
Get a front Arb locker installed. The 99 will go most any place u point it. The challenge is the front diff is a weak link.
 
...a bit off topic but

Can someone point me to a good thread that explains, The trac system/diff lock/ VSC/ hi/lo settings?


I know that based on the year this changes a bit; however a broad overview of what to use in varying conditions as well as what that particular setting does to the truck would be nice.

Thanks


Sent from my iPhone, please embrace the typos
 
How many adults and how much gear total will be traveling with? Three good size guys in the rear seats with gear will lower the rear down quite a bit. You will need to worry more for this as you might scrape the spare tire/hitch/bumper. This can cause one to get hung up as I did two times.
This was an issue with my LC, now that I have the rear coil spring airbags in, it's been great.

My opinion I say yes. My 1998 with rear locker is more capable than most of the other stock 4X4 trucks and jeeps that caravan with. This year I have done over twenty off-road trips in very harsh rocky muddy washed out up/down hill conditions. Haven't gotten stuck yet. My buddy's Jeep had to use his (he seems a little happy footed) winch a five times because of getting stuck, me zero.

If you pick the right line you should be fine.[/QUOTE]

I'll have 4 people and gear in truck. Thanks for the heads up about spare an hitch.
 
Oh, other than the torque up front T-bars, rear coil-spring spacers and airbags, my suspension is all stock.
 
Not sure if anyone answered your initial question directly.

The system is awd full time. You can lock the center diff in 4hi by pressing the cdl button. This would behave similar to your jeep in 4hi. Front and rear driveshafts turn at the same rate. Without cdl engaged you can spin one wheel alone.

Shifting into 4lo automatically engages the cdl. At this point the vehicle acts like a normal 4x4 in low range. Front and rear driveshafts turn at the same rate.

The rear diff lock will lock up the rears, but not the front (obviously). Factory lockers can take a few seconds, even minutes, to kick in. Turn this on BEFORE you approach a tough obstacle. It will be hard to engage mid obstacle. This shouldn't be used on normal roads, only loose traction terrain.

The ifs doesn't affect the 4wd system, per se. If you were used to a fully locked xj then the arb front locker might be a good mod for the cruiser.

Most people are surprised how capable a stock cruiser is. Take good lines, don't try to force bad angles and you should be fine.

My 0.02 as a new comer who's already done some moderate-difficult Colorado trails in a stock cruiser with 285/75 tires.
 
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Also,if the truck is new to you, you will want to ensure the rear diff will engage. Find a dirt road or loose surface parking lot and make sure the rear diff will engage. On a lot of these trucks, the rear diff has never been used. You do want to test it the first time you really need it. ;)

I think we might have missed a very important point, what tires are you running? Tires make a huge difference. Stock, AT or MT?
 
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If you put it into "lo" then you are automatically locking your center diff. Pressing the center diff button again is....well....Nevermind. Spend some time on this site and you'll see some intense expedition equipped 100's that can do amazing things. I've found that part of the issue for newer LC100 owners including me, is that this truck drives so much like a large sedan and is so refined it honestly feels too fragile to to anything. But push it and you'll start to get a sense of what it can do
 
suprarx7nut said:
Not sure if anyone answered your initial question directly.

The system is awd full time. You can lock the center diff in 4hi by pressing the cdl button. This would behave similar to your jeep in 4hi. Front and rear driveshafts turn at the same rate. Without cdl engaged you can spin one wheel alone.

Shifting into 4lo automatically engages the cdl. At this point the vehicle acts like a normal 4x4 in low range. Front and rear driveshafts turn at the same rate.

The rear diff lock will lock up the rears, but not the front (obviously). Factory lockers can take a few seconds, even minutes, to kick in. Turn this on BEFORE you approach a tough obstacle. It will be hard to engage mid obstacle. This shouldn't be used on normal roads, only loose traction terrain.

Thanks for educating me. I saw a youtube video of some Toyota's on a roller ramp testing their systems. Idea was to prove that their 4wd or awd system were not true vs a Subaru. Also, some guys (mostly solid axle guys ) saying that my LC is not true 4x4 like a jeep. That's why I want to see exactly what the wheels do, and how they receive power in each setting.

uzj100 said:
Also,if the truck is new to you, you will want to ensure the rear diff will engage. Find a dirt road or loose surface parking lot and make sure the rear diff will engage. On a lot of these trucks, the rear diff has never been used. You do want to test it the first time you really need it. ;)

Good point, ice would be a great test surface to validate spin.

I think we might have missed a very important point, what tires are you running? Tires make a huge difference. Stock, AT or MT?
Click to expand...

I bought some treadwright.com retreads that are basically the Wrangler MTR, helluva tire and good value

Muddy Bean said:
If you put it into "lo" then you are automatically locking your center diff. Pressing the center diff button again is....well....Nevermind. Spend some time on this site and you'll see some intense expedition equipped 100's that can do amazing things. I've found that part of the issue for newer LC100 owners including me, is that this truck drives so much like a large sedan and is so refined it honestly feels too fragile to to anything. But push it and you'll start to get a sense of what it can do
Click to expand...

Understand. So what do the wheels do if you driving without off road button engaged in "all time 4wd". What does this mean?:meh:

The Mack said:
Oh, other than the torque up front T-bars, rear coil-spring spacers and airbags, my suspension is all stock.
Click to expand...

Are this items installable with common hand tools? What was material cost?
Click to expand...
 
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Yes, you can do all of this with the right wrenches, jacks, and jack stands.

There is a Sticky on this forum for FAQ's. I would suggest you roll through these topics first. You will find a tremendous amount of information in vetted threads that the community has taken the time to create.

Anything from step by step instructions, material listings, etc.
 
DJWUZJ said:
Yes, you can do all of this with the right wrenches, jacks, and jack stands.

There is a Sticky on this forum for FAQ's. I would suggest you roll through these topics first. You will find a tremendous amount of information in vetted threads that the community has taken the time to create.

Anything from step by step instructions, material listings, etc.
Click to expand...

I agree with you. I will search for details on vetted threads on upgrades, repairs, etc.

But, when I search for technical data or an operational breakdown on the 98-99 UZJ100 4WD system and I have not found anything. I do not mean the basic. I mean in detail of a proven break down of how the wheels spin in each setting. some of the guys here have explained the way the Center diff works and that when I shift the lever into Lo in automatically Locks the center, sending power to the front. Is it 50/50? Limited slip? Does it send power to one wheel if the other spins? I am locked in the rear does than mean both rear wheels get 230hp x (gearing) at each rear wheel while the fronts are getting limited slip??? I feel like this subject is not touched on in detail.
 
Muddy Bean said:
If you put it into "lo" then you are automatically locking your center diff. Pressing the center diff button again is....well....Nevermind. Spend some time on this site and you'll see some intense expedition equipped 100's that can do amazing things. I've found that part of the issue for newer LC100 owners including me, is that this truck drives so much like a large sedan and is so refined it honestly feels too fragile to to anything. But push it and you'll start to get a sense of what it can do
Click to expand...

Just to be clear: putting the transfer case to "lo" will NOT automatically lock the center diff. (at least not on my '06) the center diff is only locked by pressing the center diff lock button.
 
sonk76 said:
Just to be clear: putting the transfer case to "lo" will NOT automatically lock the center diff. (at least not on my '06) the center diff is only locked by pressing the center diff lock button.
Click to expand...

98-99 require pin 7 mod. 2000+ is selectable center lock for Low Range.
 
But then why do the 7pin mod... if in 4L the center diff is unlocked there would be no point


Sent from my iPhone, please embrace the typos

Haha nevermind thx rob you posted just as I wrote that


Sent from my iPhone, please embrace the typos
 
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I chose the 100 series based on a ton of research. The most valuable factor was reliability with good off road capability.

However, when I have a guy at work saying his p30 range rover is a true 4X4 and another guy saying his ZJ is a true 4x4 and my 99 TLC is not, that makes me want ammo to talk specs! I searched and searched and failed when trying to find what my 99 4wd system actually does.

http://youtu.be/2OzK-oRPCbs

This link is curious to me. Particularly when it comes to my questioning of the "Full time Awd" system. I would to see my TLC on this ramp vs a ZJ or WJ vs a Range Rover and go through all the settings for each.
 
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It doesn't get any more 4x4 than your land cruiser. I have noted that some folks will say that because the 100 doesn't have a solid front axle that it's not a real 4x4... Just because they say doesn't make it true.

Be secure in your truck-hood. Out in the real world you're not going to get sand kicked in your face.
 
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