KJ 4WD systems - Select Trac

richo · **Posted:** Mon Jul 09, 2007 10:28 pm

Hi All,

I would like to know more about the KJ 4wd system

When should I use the following;

4wd full time
4wd part-time
4wd lo

When I go through thickish mud (in 4wd high), the KJ start sliding all over the place.

Cowcatcher · **Posted:** Mon Jul 09, 2007 10:46 pm

I am not an off road specialist but I got in some muddy conditions on a mountain road a year ago in full time and very nearly went over an embankment that might have kept me rolling 1/2 to 3/4 of a mile, the back kept wanting to pass the front and therefore the Jeep was crabbing with the right rear wanting to slip over the edge. I put it into part time and then it pulled straight. When I got away from the edge I put it into low, changed my underware and resumed down the next couple of miles of mud and mountain at about 1/4 mph.

Short answer...full time has a rear wheel bias of somewhere between 6/8%.

richo · **Posted:** Mon Jul 09, 2007 11:02 pm

thanks,

so the part-time 4wd means that all 4 tyres rotate at the same speed - locking the diff

Is this the same as 4 lo??

Alak · **Posted:** Mon Jul 09, 2007 11:53 pm

4 LO uses gearing to multiply the Tourque by a ratio of 2.72:1. This means you get more tourque and far more traction, but do not exceed 40kmph (about 25MPH or so).

In the owners manual, it says to use 4LO for Sand, Thick Mud, or very steep inclines.

jason thompson · **Posted:** Tue Jul 10, 2007 12:09 am

richo wrote:

Hi All,

I would like to know more about the KJ 4wd system

When should I use the following;

4wd full time
4wd part-time
4wd lo

When I go through thickish mud (in 4wd high), the KJ start sliding all over the place.

you satarted to slide because you were going to fast
the rule that I live by out on the trails is that if you need 4wd then it should be in 4lo
In the TJ I have NEVER used 4 high and have wheeled from TX to NC and then some
We have that same T-case in the KJ as you and we have quite a few times use the full time mode up in the smokie mnts when we were getting snow but other than that it is 4lo when off road
I could see useing 4 high if you were driving down muddy 2 tracks but not out on the trails you just can not go slow enough

richo · **Posted:** Tue Jul 10, 2007 12:28 am

thanks guys,

So what is the real difference between the 4 high & 4 part time??

It says something about the wheel rotations or something. Can someone tell me in trail terms??

Also, is it ok to switch in and out??

Jeepjeepster · **Posted:** Tue Jul 10, 2007 12:33 am

4high is part-time..

Full-Time allows the front and rear axles to rotate at different speeds which is good for on-driving in rain or light snow..

Part-Time if good for sand, heavy snow, or mud where you need speed..

4low is good for high torque situations..

jason thompson · **Posted:** Tue Jul 10, 2007 12:39 am

richo wrote:

thanks guys,

So what is the real difference between the 4 high & 4 part time??

It says something about the wheel rotations or something. Can someone tell me in trail terms??

Also, is it ok to switch in and out??

the easiest way that I can explain it with out making things worse
picture the path your wheels take when you make a turn
if you turn to the right the left tire travel further than the right this is made possable by your differental on the front and rear because all 4 tires want to travel at different speeds in a turn if you lock the front and rear togeather then it will bind and cause a knock ,nothing real bad just some tire scrubing and stuff like that

in 4 part time as well as 4 low the front and rear drive shafts turn at the same speed NO MATTER WHAT thus causeing bind if the tires can not slide some what
now in 4 full time the front DS will only turn when the front tires turn slower than the rear ,kinda sorta
just look at it like this
You can run full time 4wd all the time ,thus FULL TIME
now part time is just that ,use it PART TIME
and 4 low use it on the trails

richo · **Posted:** Tue Jul 10, 2007 2:55 am

thanks, this really helps.

I appreciate everyones response.

Does this this mean that my KJ has diff locks (in 4 part-time & 4 low)? If so, what is the difference between standard diff locks and getting an aftermarket air locker???

Jeger · **Posted:** Tue Jul 10, 2007 6:01 am

It does NOT have diff locks. They are standard "open" differentials. The transfer case however DOES lock in part time 4WD and 4 LO...forcing the front and rear driveshafts to turn at the same speed. The wheels on one axle can still turn at different speeds though. The aftermarket diff locks will fix that.

Fulltimer · **Posted:** Tue Jul 10, 2007 7:12 am

Maybe you already know this. In 4 wheel drive you have 1 rear tire and 1 front tire doing the work. It isn't really 4 wheel drive unless you add lockers.

Terry

Jeger · **Posted:** Tue Jul 10, 2007 8:12 am

Fulltimer wrote:

Maybe you already know this. In 4 wheel drive you have 1 rear tire and 1 front tire doing the work. It isn't really 4 wheel drive unless you add lockers.

Terry

Or have ESP....just to confuse things more LOL

FYI....you dont have esp unless you have an '06 or newer...

tjkj2002 · **Posted:** Tue Jul 10, 2007 9:38 am

The 242(select-trac) t-case has a limited slip diff in it,in full time 4wd it allows you to drive in 4wd on hard surfaces,lets the front and rear driveshafts to turn at different speeds.Part time and 4low is for surfaces where the tires can slip because then the diff in the t-case is locked and force the front and rear drive shafts to turn the same speed,and will cause drive line bind on hard surfaces.

As far as only driving only 2 wheels in 4wd,that is right,1 in the front and 1 in the rear.ESP will not give you true 4wd,only lockers front and rear will.Lockers will lock both axles together forcing them to turn the same speed no matter what,even if one tire is in the air.ESP will only apply the brake to the wheels acting like a locker but it is not in any way a locker.Just remember torque will go to the path of least resistance,so if you lift a wheel all the torque goes to that wheel with open diffs,ESP just applies the brake to that wheel forcing the torque to the wheel still on the ground.

DarbyWalters · **Posted:** Tue Jul 10, 2007 9:45 am

GREEN Full-Time light means you are good to go on any surface

AMBER Part-Time light means caution...use on very loose surfaces that have limited traction

4LO is for treacherous terrain where control (slow) is called for

richo · **Posted:** Wed Jul 11, 2007 5:28 am

thanks again,

another queston - if its a very loose & slippery road and you are in 4 part-time, is it ok to be turning, if the road curves somewhat. does this mode allow you to turn without the kj going out of control?

Also, is this 4 wd system similar to other 4wd's?

sleeve84028 · **Posted:** Wed Jul 11, 2007 7:47 am

Yes the 4x4 is identical to other systems, minus the Jeep logo and the full-time option.

You could run the part-time system on a dirt road but there would need to be enough slip in traction to allow the tires to freely spin. If you have too much traction, it'll bind up the system and make the Liberty start bouncing around. Some people on the board have reported using the part time system in snow and on rain slicked roads but I don't know how effective that is.

If you have the Full-Time system, just use that one when running around on the roads and save the other two for off-road action.

richo · **Posted:** Wed Jul 11, 2007 8:28 am

thanks again,

what is the difference from normal 2wd to 4wd full-time? Is full-time worth it?

If i'm crossing a river, what mode should i be in?

Jeger · **Posted:** Wed Jul 11, 2007 9:44 am

richo wrote:

thanks again,

what is the difference from normal 2wd to 4wd full-time? Is full-time worth it?

If i'm crossing a river, what mode should i be in?

If you are crossing a river you should be in 4LO. Unless you are being chased by flying monkeys...in which case you would want to be in 4HI part time to outrun them :lol:

.

Full time 4WD is definantly better than 2 wd, especially in slick on-road conditions. The difference is that power is being sent to the front wheels as well as the back.

So you have:

2wd...power to rear driveshaft only

4wd Part Time.....power to front and rear driveshaft with driveshafts locked together so they turn at the same speed. Driveline can bind up if tires dont slip.

4wd Full Time....power to front and rear driveshaft with driveshafts NOT locked together so they can turn at different speeds. Driveline can NOT bind up even if tires dont slip.

Neutral.....now power to either drivshaft

4wd Low...same as 4wd Part Time except it is geared to go slow.

bugnout · **Posted:** Wed Jul 11, 2007 9:58 am

I use 4 full-time a lot. Basicly, its the same as the all wheel drive (AWD) systems in other cars. I find it makes my KJ very stable on wet roads and in the snow, When I first got my KJ, I swapped ends one rainy night, when both rear wheels broke loss on a slick road (I have Trak Lok rear). That was interesting, I find it much safer to put it in 4 Full-time anytime the roads are wet. It does reduce my MPG slightly, but I shift the transfer case at the first sign of moisture, and back to 2WD when the roads dry up.

sleeve84028 · **Posted:** Wed Jul 11, 2007 12:39 pm

bugnout wrote:

I use 4 full-time a lot...

I also use my "Full-Time" system when ever I drive through inclimate weather. It just makes getting around a little smoother and I never have to worry about traction since the T-case shifts the power to the proper axle (open diff's.) The added power split does take a little power away from the vehicle but it is really worth it when Mother Nature is in a bad mood.

Side note: The wife considers the Liberty to be "All Weather Rated" rather than "trail rated" since my early model missed out on that ever so important badge and marketing stuff.

Everyone else pretty much coverd the usages behind the respective systems :woot:

KJ 4WD systems - Select Trac

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