Command Trac question

I reconnected the vacuum lines to the vacuum shift motor on my axle. Replaced is more like it. Dry rotted.

When I had my Cherokee up on jack stands to test the 4wd to 2wd (and back) change over I noticed that both front wheels would turn when in 4wd, but only 1 rear wheel would turn, obviously the rear diff is open, but is the front diff not an open type? If the front axle is in 4wd, in neutral, and I spin the right tire, the left tire spins in the opposite direction and vice versa. Open diff or not?

BTW, its an 86 XJ with 2.8l, TF904 auto, NP-207, Dana 30 front, and Dana 35 rear. With Command-Trac of course.

Open Diff.

The back probably has more resistance (brake shoe, bearing...) or something is keeping both from turning freely. On the front if you gave one of the wheele some resistance it woul stop and then you would only have one spinning like the back.

I have heard that when u put a Jeep in 4WD it doesn't actually make all the wheels move at the same time. It locks the front 2 wheels to 1 of the rear wheels, so it actually isn't 4WD, more like 3 wheel drive.

If you want "full" 4WD then you need to get lockers. Like I said this is only what I heard and it probably is a bunch of bull but it is interesting anyway.

XJRedneck said:

I have heard that when u put a Jeep in 4WD it doesn't actually make all the wheels move at the same time. It locks the front 2 wheels to 1 of the rear wheels, so it actually isn't 4WD, more like 3 wheel drive.

If you want "full" 4WD then you need to get lockers. Like I said this is only what I heard and it probably is a bunch of bull but it is interesting anyway.

Click to expand...

It locks the front driveshaft to the rear driveshaft. Each axle then differentiates between its two wheels. If one wheel has traction and the other does not, then the power goes to the path of least resistance. If both wheels have traction, then they are both driven. But power is sent to both axles equally when in part-time 4wd. Full time 4wd places a differential between the two driveshafts which allows for pavement operation of 4wd, but also adds the caveat of power sent to the axle and wheel with the least traction. Lockers defeat this differentiating action, akin to part-time vs full-time 4wd modes.