Differences between 4WD systems

jelohead · **Posted:** Fri Mar 16, 2007 9:02 pm

ok, forgive my ignorance, but can someone explain to me really simply the differences between my command trac, a limited slip, and selec trac?
i know what a locker such as a softlocker does....100% traction 100% of the time, but i still dont understand how even a standard 2 wheel drive/4 wheel drive sysytem actually works. one wheel on each axle driving? ok folks, fire away.......

1300ZUK · **Posted:** Fri Mar 16, 2007 10:04 pm

Oh boy

the differences between Command Trac and Select-trac are:

Command Trac is a regular 2 speed transfer case that is to be used part time and really only in low traction, this is because the front and rear driveshafts have to turn at the same rate.

Select trac is a 2 speed transfer case, but it has a FULL-TIME position, which you can use all the time if you wish, it allows for some variances between front and rear driveshafts. (i think it uses a viscous coupler)

Limited SLip (aka Posi-traction), is a traction deviece that is in the differentials that takes the place of convential spider gears. it allows from some slippage from side for turning. It can still allow for big differences in tire rotation.

and one wheel peel on lots of stock vehicles is caused by by an open differential (conventional spider gears) and since torque is lazy it takes the path of least resistance, hence the wheel you don't want spinning spins, and the wheel you wish was spinning does nothing.

jjbroze · **Posted:** Fri Mar 16, 2007 10:05 pm

Go to this url: http://www.jeep.com/jeep_life/index.html# and click on 4x4 101. Go info on all the various 4 wheel setups.

Jeepjeepster · **Posted:** Fri Mar 16, 2007 11:12 pm

1300ZUK wrote:

Oh boy

the differences between Command Trac and Select-trac are:

Command Trac is a regular 2 speed transfer case that is to be used part time and really only in low traction, this is because the front and rear driveshafts have to turn at the same rate.

Select trac is a 2 speed transfer case, but it has a FULL-TIME position, which you can use all the time if you wish, it allows for some variances between front and rear driveshafts. (i think it uses a viscous coupler)

Limited SLip (aka Posi-traction), is a traction deviece that is in the differentials that takes the place of convential spider gears. it allows from some slippage from side for turning. It can still allow for big differences in tire rotation.

and one wheel peel on lots of stock vehicles is caused by by an open differential (conventional spider gears) and since torque is lazy it takes the path of least resistance, hence the wheel you don't want spinning spins, and the wheel you wish was spinning does nothing.

The select trac is only an open diff. I believe the only tcase that has a VC is the tcases in the ZJ's and WJ's.

jelohead · **Posted:** Sat Mar 17, 2007 7:32 am

thanx for the replys, but not quite the answer im looking for....when im in 4HI with my command trac, are all 4 wheels actually receiving input/torque to move my vehicle forward? and if so, how is it that sometimes only one wheel seems to be turning/spinning during very loose conditions. inside the front and rear difs, are both ends of the axle locked together, or is it truly a limited slip set up without being called so? i've never been clear on this, and im still quite confused as to how each of the 4 wheels does it's thing..... :oops:

SnowgodCCR · **Posted:** Sat Mar 17, 2007 8:44 am

All four wheels are recieving power when in 4wd with command-trac.

One wheel will spin though if you're stuck, as the power from the engine will take the path of least resistance-so the wheel with the least traction gets all the power. That's the way that open diffs work. Inside the front and rear diffs the axles are open, the center diff is the one that is locked. A standard KJ doesn't get LSDs or Lockers, but they can be added. Hope that answers...

Jeger · **Posted:** Sat Mar 17, 2007 8:49 am

In 4HI part time...like your command trac, both front and rear driveshafts get the same amount of power and spin at the same speed.

The "open" front and rear differential is what allows one tire on on axle to spin while the other is doing nothing. Limited slip differentials help, and a locker will completely stop this annoyance.

Command trac and selec trac are transfer cases

limited slip refers to the differential

jelohead · **Posted:** Sat Mar 17, 2007 10:04 am

thanx guys....starting to become a little clearer now....still not quite sure how the LSD differs from the open dif.....and thanx jeger re: the dif vs the t-case, i sorta knew that....lol....regardless, my 2 hour, 50 mile ride home yesterday in the st pattys day blizzard using 4HI the entire ride was flawless! i love this freakin KJ!!!

Differences between 4WD systems

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