UZJ100 4x4, 4wd system explained

[stonepa]

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.

If by "not true 4x4 like a jeep" (at least in stock form) they mean it doesn't break a critical component, puke fluids all over the ground, or look like every grocery getter in my town, then, yeah, it's not a true 4x4.

That being said, I've seen some beautifully 'built' Jeeps out there. I just wouldn't want to rely on them for all of my needs. They seem a bit 1-dimensional.

 

[SkiLyft]

My truck has a cargo box = +5HP
And the stickers add an additional +10HP

My consensus is that I have a real 4X4




Sent from my iPhone, please embrace the typos

 

[DanInDenver]

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.

Do not talk, DO!
Just wheel the Motherf$&@er!

 

[DJWUZJ]

^^ what he says!

Look 1/3 of the way down the page for info on the system.

http://townhall-talk.edmunds.com/direct/view/.f0d6fd4.eeca1cf/0

 

[hoser]

Some would say true 4wd's have Front, Rear, Center differential locks.... and low range. That eliminates the RR P38, ZJ and LC100 in stock form.

 

[Jody Highroller]

QUOTE=DJWUZJ;8966559]^^ what he says!

Look 1/3 of the way down the page for info on the system.

http://townhall-talk.edmunds.com/direct/view/.f0d6fd4.eeca1cf/0[/QUOTE]

Thanks for the link. I've read it before and it's a great report. But it's defining 2000- and beyond 100s with ActiveTrac.

In my group of hunting buddies, there is not a lot of modding. It's all pretty much factory stuff, and its some ruff mountain. If it gets too slick we ride the razor or atvs. But the consensus of the group is we like the warmth of the jeep. But now the jeep is needing maintenace and so of course it's my TLC they want to roll up in.

 

[Junglejack]

Pretty sure the AWD is unchanged. ATRAC/TCS can sometimes sort of act like super ABS, and it is engaged when things get squirrely not in general operation. If your 100 has an "L" instead of sombrero, that might explain the perception relating to capability. As has been said, just stab it and steer and show your palominos what it can do. Provided it is not equipped with 20 inch spinners or whatnot.

 

[uzj100]

Actually u have true 3 wheel drive, 2 drive with locked rear axle and 1 drive in the front axle. Unless your Jeep and rover friends have installed aftermarket lockers their axles are open. Your lc has a rear axle locker which will help a ton. When you engage low range in most trucks that usually just locks the center diff with two open axles. You will be good to go.

Don't forget to test rear locker engagement prior to needing it.

 

[sonk76]

98-99 require pin 7 mod. 2000+ is selectable center lock for Low Range.

Thanks for the clarification! I wasn't aware of the difference across years. Makes me always weary of commenting on anything other than my specific model year...

 

[Jody Highroller]

Actually u have true 3 wheel drive, 2 drive with locked rear axle and 1 drive in the front axle. Unless your Jeep and rover friends have installed aftermarket lockers their axles are open. Your lc has a rear axle locker which will help a ton. When you engage low range in most trucks that usually just locks the center diff with two open axles. You will be good to go.

Don't forget to test rear locker engagement prior to needing it.

Ok thanks. So does that mean that a zj pr RR p38 when in 4 low is the same as my 99 with the center diff button pressed and the shift lever in 4 low? What is the button for??? Does the zj center diff do an auto lock when in 4 low?

 

[uzj100]

Yes. Jeep and rover have center diff lock in 4 low. 50 / 50 torque split to each axle. Same as your 100. You have the advantage of rear diff lock if things get more difficult.

The center diff lock button is for 4 high on the 98 and 99 unless you do the 7 pin mod. 4 high locked is good in sand or snow. 4 low with center diff unlock is great for tight trails and moving trailers around if the conditions are messy.

 

[larss]

I'm no expert here but I think we're over complicating this...

The 4wd system in 98-99 100s is pretty simple. Under normal conditions, power is sent to both the front wheels and rear wheels. Don't think there's any percentage "split," it just acts like an open diff. If one wheel looses traction then the other three won't turn. Similar to how a 2WD car won't move when one drive wheel looses traction.

The CDL button is for when you're off road or on snow/rain/ice. This will lock the center diff so the front drive shaft spins at the same speed as the rear. You don't want to leave this engaged on dry pavement as it will cause binding in the drivetrain. Most "part time" 4WD trucks ONLY have a locking center diff, so the manuals will say to only engage it on slipper ground.
With the CDL engaged, one front wheel AND one rear wheel would have to loose traction before you stop moving. It is automatically engaged in 4Lo because lets face it, if you're wheeling you want it engaged.

Locking the Rear just takes the above scenario one step further. Now the two rear wheels (and one of the front wheels) will all spin at the same speed. So three wheels will have to loose traction before you stop spinning.
Transfer case has to be in 4Lo to engage the rear locker and you will also loose ABS.

That's all there is to it!

Like others have said, I would be surprised if your friends' Jeeps with Minimal mods had a locker on the front or rear. Ergo you should have the more capable rig.

 

[Jody Highroller]

I'm no expert here but I think we're over complicating this...

The 4wd system in 98-99 100s is pretty simple. Under normal conditions, power is sent to both the front wheels and rear wheels. Don't think there's any percentage "split," it just acts like an open diff. If one wheel looses traction then the other three won't turn. Similar to how a 2WD car won't move when one drive wheel looses traction.

The CDL button is for when you're off road or on snow/rain/ice. This will lock the center diff so the front drive shaft spins at the same speed as the rear. You don't want to leave this engaged on dry pavement as it will cause binding in the drivetrain. Most "part time" 4WD trucks ONLY have a locking center diff, so the manuals will say to only engage it on slipper ground.
With the CDL engaged, one front wheel AND one rear wheel would have to loose traction before you stop moving. It is automatically engaged in 4Lo because lets face it, if you're wheeling you want it engaged.

Locking the Rear just takes the above scenario one step further. Now the two rear wheels (and one of the front wheels) will all spin at the same speed. So three wheels will have to loose traction before you stop spinning.
Transfer case has to be in 4Lo to engage the rear locker and you will also loose ABS.

That's all there is to it!

Like others have said, I would be surprised if your friends' Jeeps with Minimal mods had a locker on the front or rear. Ergo you should have the more capable rig.

If while I'm in 4wd and one wheel loses traction and it makes my other 3 stop turning....I need to sell this.

 

[FlammableFishie]

If while I'm in 4wd and one wheel loses traction and it makes my other 3 stop turning....I need to sell this.

That's where ATRAC comes in. You can keep it.

 

[Jody Highroller]

That's where ATRAC comes in. You can keep it.

98-99 do not have active trac (ATRAC)

 

[FlammableFishie]

98-99 do not have active trac (ATRAC)

Sh*t. You're right... Brain fart. You can still keep it though, nobody would be raving about these if they stopped moving after one wheel loses traction. That'd just be stupid.

 

[Jody Highroller]

Sh*t. You're right... Brain fart. You can still keep it though, nobody would be raving about these if they stopped moving after one wheel loses traction. That'd just be stupid.

Very true. That's why I think his post could be technically wrong. I may not ever find real engineering data on how this 98-99 works. Even a Subaru with symmetrical 4wd system sends power to the wheels that are not spin whenever the others lose traction..

The link I posted is am excellent 4wd drive test. They use a roller ramp to prove that toyota and Honda "full-time 4WD systems are worthless. If the poster who "simplified it" is correct I will be getting a different vehicle, very soon. Btw, I've had my off road with these a MTR retreads and I've not been stuck. But where I plan on going is the roughest test thus far.

 

[uzj100]

Guys. The truck is full time 4wd. That means power is moving where it needs to go all the time. Like a rally car. Actually every 4wd without a locked center or locked axle or electronic aids would be stuck with 1 wheel stuck. When u go to 4 Low and the center diff locks u then have one wheel per axle that can assist. Then beyond that is axle locks.

Watch some you tube videos. These trucks are crazy good in stock format and used by the United Nations and many military's. no Heeps or rovers are used these days.

 

[RKFZJ80]

If while I'm in 4wd and one wheel loses traction and it makes my other 3 stop turning....I need to sell this.

Agreed! I'll be happy to take it off your hands I would hate for you to get stuck

 

[Jody Highroller]

If loss of traction occurs, shouldn't power be distributed to the wheel that has traction, not be eliminated and therefore stop turning