MickDime

I got a 99 XJ with both..usually use full-time, wondering what part-time is all about. 4low is more torque I know that much at least.
thanks

Diesel

NP242? If you have the option between 4 and 2, 2 should be used all the time. 4 should be used in operations where slipping is highly possible.

MickDime

For normal road use I have it in 2WD, but for slippery conditions I use 4WD Full-time. What is 4WD part time used for?

Gee oh Dee

If its anything like the Explorers its just 2wd until the Tcase senses slip between front and rear wheels, then automatically kicks it into 4. You almost won't feel it.

Diesel

4w part time should be used in conditions like snow and mud. it relies on slipping to engage and disengage itself

Gee oh Dee

It should use the heating of fluids to lock and unlock into 4. The friction generated by the slip generates the heat.

At least this is how it works in an AWD DSM, and the Explorers too if I'm not mistaken.

Diesel

You ever hear of someone not being able to get it out of 4? And then what solves it is them getting off pavement and trying it? Without slip it locks itself

Paco182

4 full time is like an open differential, it can power front and rear wheels but allows them to turn at different speeds (when you turn a corner). It can be used anytime as there is no danger of damaging your transfer-case. 4 part time locks your axles together. With it engaged on the street, turning will; wear your tires, make them hop and put stress on your transfer case. It is important to use part time in slippery conditions only.

Blizzard

+1, I just read through the entire owners manual a week ago including the insert about the Selec-Trac transfer case.

4wd part time = front and rear axles locked together, ONLY for use on loose or slippery surfaces

4wd full time = front and rear axles NOT locked together. Jeep's literature says this mode can be used any time, even on dry pavement since the front and rear axles are not locket together. Power distribution in this mode is Front=48% Rear 52% (I think I remember that correctly).

blkonblk

ok just to clearify this up. i can use my 4x4 fulltime when im in the snow but traveling on the pavment at normal 45+ speeds? just want to make sure....dont want to damage the Tcase

Pistol-McGee

^ Yes, i think up to 55 mph you can shift into full-time (dont quote me on the speed but i know you can do it while driving) and full time can be used on the street. Part time can ONLY be used on slippery surfaces that allow slippage of the tires.

longship

I use 4fulltime, all the time. Never had any issues.

Some say this will wear the front components out quicker. So be it.

Rob

OttawaXJ

I always stop to switch to 4x4 but I've heard you can do it up to 80km/h

OOdynamite

Don't you also get bad MPGs when in 4WD?

no rdplz

2wd is what should normally be used for driving on pavement.
Full time 4hi can be used on pavement as well, and can be engaged at speeds up to 45mph. Full time 4hi is not available on NP231 transfer cases. Some XJ's came with the NP242 t-case which offers full time 4hi.
Part time 4hi should only be used in conditions where the tires are slipping (non pavement), and can be engaged at speeds up to 45moh
Part time 4lo should only be used in conditions where the tires are slipping (non pavement), and should should only be engaged after the vehicle is at a complete stop and the transmission is put into neutral.

You will see lower mpg's when 4wd, whether full or part time, is engaged.