[noasad]

i pull up on my "4Hi" and just the part time light lights up then i read on the internet there is 4 x4 full time and a 4 x 4 low , 3 seetings but all i have is 4 hi and 4 low and when in 4 hi it just says partime

what does partime ?

how do you get it into 4 high fullltime?

thanks

[Bgeddes]

Two different transfer cases. Some have full time 4x4, some only have part time.

[noasad]

what is the difference between partime and full time?

thansk

[ivorycruncher]

The full-time system is electronically controlled. The computer engages 4wd mode as needed when it detects traction problems. You can safely leave 4wd mode with this system on any surface, including dry pavement.

On the other hand, the part-time system, when engaged in 4wd high, mechanically locks the front and rear driveshafts together. This 4wd mode cannot be used on firm ground, unless you want to risk damaging your drivetrain. I'm not sure exactly how this works, but the front wheels on a vehicle turn a bit faster than the rear wheels. When the front and rear wheels are locked via driveshaft and forced to turn at the same speed, it causes bind-up in the drivetrain, which can cause erratic jerking when driving and quite possibly damage to the transmission, transfer case, etc. This system should only be engaged on loose dirt, icy roads, etc., where conditions allow the wheels to spin easily and prevent the bind-up.

[panthermark]

There was Selec-Trac and Command-Trac offered on the KJ's.

You can drive in a straight line (only) on dry pavement in part-time 4wd...but there is really no need for it. The binding comes from turning with the locked axles. When you turn, the outside wheels turn faster then the inside wheels...but with the axle locked and moving at the same speed....something has to give.

[Jakked]

Originally Posted by panthermark

There was Selec-Trac and Command-Trac offered on the KJ's.

You can drive in a straight line (only) on dry pavement in part-time 4wd...but there is really no need for it. The binding comes from turning with the locked axles. When you turn, the outside wheels turn faster then the inside wheels...but with the axle locked and moving at the same speed....something has to give.

Exactly. If you feel the need to give your part-time 4-Hi a good run once in a while, you can do it on dry paved roads, provided you're traveling in a straight line and there aren't any major suface imperfections (potholes, rumble strips, etc). And you can shift into/out of part-time 4-Hi at speed.

[ivorycruncher]

Ah, I was told to never use it on dry pavement, ever. I guess it's the old "better safe than sorry" mentality, which makes sense. But I can tell you that with my 99 Explorer that I traded in for my new KK, there were times when I had 4wd high on over mostly straight dry pavement, and every so often it would jerk rather harshly, so I would say you're better off leaving it off. Like you said, what's the point of having it on for dry roads anyway?

To be perfectly honest, I wish they'd combine the two systems. My Explorer was all-time 4wd auto, with 4wd high and 4wd low selections on the control knob. I had it all in one 4wd system, except for a true 2wd mode of course. But then again, Jeep's 4wd systems are supposedly superior to all, so they must be doing something right.

[jeepjeepster]

Originally Posted by ivorycruncher

The full-time system is electronically controlled. The computer engages 4wd mode as needed when it detects traction problems. You can safely leave 4wd mode with this system on any surface, including dry pavement.

On the other hand, the part-time system, when engaged in 4wd high, mechanically locks the front and rear driveshafts together. This 4wd mode cannot be used on firm ground, unless you want to risk damaging your drivetrain. I'm not sure exactly how this works, but the front wheels on a vehicle turn a bit faster than the rear wheels. When the front and rear wheels are locked via driveshaft and forced to turn at the same speed, it causes bind-up in the drivetrain, which can cause erratic jerking when driving and quite possibly damage to the transmission, transfer case, etc. This system should only be engaged on loose dirt, icy roads, etc., where conditions allow the wheels to spin easily and prevent the bind-up.

You are right about the part time but not right about the full time.

The kj's selectrac has an open diff in the tcase and lets the torque go to the front or rear axle as it pleases. It does NOT work like a KK and Im personally glad it does not.

noasad, the select trac transfer case lets you have the option of running on any surface while in 4wd, this is called full time, meaning you can run 4wd 'FULL' time. The part time means just that, you can only use 4wd 'PART' of the time. Never use part time on hard surfaces.