Part time vs full time

[Cwish]

Dont make fun..kinda new but what is the honest difference between part time 4wd and full time

[Mudderoy]

Dont make fun..kinda new but what is the honest difference between part time 4wd and full time

Hey I didn't have a clue when I got my first Jeep. The NP242 has full time, part time 4 hi. The 4 hi means you can drive fast with it in 4x4. The full time means you can have it in 4x4, go fast, on normal dry surfaces. No slippery conditions necessary.

The 4 hi part time is for only the most slippery conditions. You can drive normal speeds but generally the conditions aren't going to let you.

The difference between full time and part time is in full time the front and rear differentials are NOT locked together. So when you make turns the front wheels, turning faster aren't binding up on the rear wheels turning slower.

In part time the front and rear differentials are locked. The front differential turns at the same rate as the rear. This is great for traction and going straight.

If you run part time on a dry surface and make a turn, a lot of stress builds up in the drive train, and normally what happens is the chain in the transfer case pops as it jumps over the drive and driven gears. This can lead to heat build up and the chain stretching. Of course the many other components that make up the drive train (not so much the engine or transmission) can break during this high stress situation, but normally it's the transfer case.

What really curled my hair was finding out that when I have it in 4 hi part time I don't have a 4 wheel drive, I have a 2 wheel drive! One wheel in the front and one wheel in the back are locked together. To get all four wheels locked together for maximum transfer of power to the ground, well you need lockers.

[willpoot]

Good question Cwish, I am new to this as well. I am going to be lifting mine at some point. I have never heard of lockers. I thought I had 4 wheel drive. Is there anyway to test, to know for sure if you have lockers or not. I assume that if you put it in 4x4 and spin the tires, if all four spin it has lockers. Or does it have to be under some kind strain.

[prerunner1982]

Lockers were not stock in the XJ, if someone has previously modified your XJ then perhaps they put a locker in it. However if it is not lifted and does not appear to be modded for off road use (bumpers, winch, aggressive tires, etc) then I would be inclined to believe it does not have a locker either.

However to test for a locker you could open the differential and inspect, after all it has probably been awhile since the fluids in the axle were changed.....if ever. If you pull the cover and you see something like the first picture below then you have no traction aid and only 1 tire actually gets power. If yours does not look like the picture below then it would be time to start researching and see what kind of traction device you have. It could be a limited slip or a locker.
http://image.4wdandsportutility.com/f/9368727+w750+st0/0705_4wd_09_z+dana_35_upgrades+rear_axle_drain.jpg

I believe you can also jack up the axle and if you turn one tire and the other turns the same direction you have a locker but if the other tires turns in the opposite direction it is an open differential....

[willpoot]

Thanks for the explanation. Feel like a preschooler on here. Just trying to learn all I can.

[Mudderoy]

Good question Cwish, I am new to this as well. I am going to be lifting mine at some point. I have never heard of lockers. I thought I had 4 wheel drive. Is there anyway to test, to know for sure if you have lockers or not. I assume that if you put it in 4x4 and spin the tires, if all four spin it has lockers. Or does it have to be under some kind strain.

Yep, lockers are pretty expensive and not necessary for driving on the street. I know some people will argue that point. :D

The best you can hope for is something called posi-track, or limited slip. The Chrysler 8.25 came with limited slip (I believe that is what they called it), but not in all 8.25. Basically it would lock both sides of the axle, sometimes. Again this is for the street really.

Here is a video that might help explain what the locker does for you. Any locker will work, it doesn't have to be ARB.

http://www.youtube.com/watch?v=9Zvvbt0Y6do

A differential is designed to put power to the wheel that needs it the least! Yeah I know. lol

[4.3LXJ]

Good question Cwish, I am new to this as well. I am going to be lifting mine at some point. I have never heard of lockers. I thought I had 4 wheel drive. Is there anyway to test, to know for sure if you have lockers or not. I assume that if you put it in 4x4 and spin the tires, if all four spin it has lockers. Or does it have to be under some kind strain.

You do have four wheel drive. What Tony was referring to is a condition where opposite corners are under low traction situations. In that situation only, you would have power going to the wheels with low traction. If you have good traction at all wheels then you have power to all of them and four wheel drive.

Lockers will change that situation. There are two types of lockers. Selectable and automatic. Selectable are more expensive, but can be turned off for good road manners and use on icy conditions. Automatic lockers will put power to either wheel that has traction, or both. They are not very highway friendly, but certainly drivable. But you have to be aware of some quirks with them. I have one in the rear of mine. One thing you have to do is have a light foot in tight corners. The power goes to the inside wheel so it is easy to chirp the tires at low speeds. There are times they will put power from one side of the axel to the other and it will feel like something just broke. In reality it is just one side unloading and the other loading. They are not recommended for use on snow and ice during highway driving. In those conditions they can be dangerous. But just about everybody that gets one uses them for off road performance, which is significantly enhanced. It is a must have for serious wheeling in mud and rocks.

[Mudderoy]

You do have four wheel drive. What Tony was referring to is a condition where opposite corners are under low traction situations. In that situation only, you would have power going to the wheels with low traction. If you have good traction at all wheels then you have power to all of them and four wheel drive.

Lockers will change that situation. There are two types of lockers. Selectable and automatic. Selectable are more expensive, but can be turned off for good road manners and use on icy conditions. Automatic lockers will put power to either wheel that has traction, or both. They are not very highway friendly, but certainly drivable. But you have to be aware of some quirks with them. I have one in the rear of mine. One thing you have to do is have a light foot in tight corners. The power goes to the inside wheel so it is easy to chirp the tires at low speeds. There are times they will put power from one side of the axel to the other and it will feel like something just broke. In reality it is just one side unloading and the other loading. They are not recommended for use on snow and ice during highway driving. In those conditions they can be dangerous. But just about everybody that gets one uses them for off road performance, which is significantly enhanced. It is a must have for serious wheeling in mud and rocks.

It's a judgment call on my part. If it isn't 4 wheel drive when I need it then it isn't 4 wheel drive. :D

[4.3LXJ]

It's a judgment call on my part. If it isn't 4 wheel drive when I need it then it isn't 4 wheel drive. :D

You shouldn't wheel outside the mall then :rolleye0012:

[jeepxj95]

@4.3LXJ would something like the tru trac be good on icy/ highways?

[bigjim350]

You shouldn't wheel outside the mall then :rolleye0012:

He doesn't.......:rolleye0012:

[4.3LXJ]

@4.3LXJ would something like the tru trac be good on icy/ highways?

Yes, it would. You want something with a little give in it, yet when you need the traction it will be there. They come in two stiffnesses. Front 30% of lockup and rear 70%

[uberxj92]

we dont get alot of ice here in florida. my jeep club ( all xj's, 1 token yj) all run the same traction set ups...auto lockers in the rear & electric in the front's.