XJ "Command-Trac" Question

I was looking at a 1999 XJ "Classic" today and the salesman said it had the "upgraded" four wheel drive system, a Command-Trac. What does this mean and how does it differ from the system I had in my '90?

TIA
Soon to be jeeping again, JeeperJeff

<snort> Command-Trac was the base model 4wd system on XJs. Parttime 4wd only.

Selec-Trac is the upgrade. It has a 4wd Fulltime position, there's a diff in the transfercase.

ChiXJeff

Upgraded is a weasel word the salesman was using when comparing an early 231 tcase to a newer one. There was a design change in the 231 "Command Trac" tcase in 1996. Basic change was that the rear output was changed. In the older tcases, the slip yoke move in and out of the rear tail cone. In the newer tcases, the output shaft is sealed by the newer tail cone, and the slip yoke just moves over the exposed tailshaft.

Plus's on the older units is that there is more support of the tailshaft because of the longer cone. Minus is that if you need to pull your driveshaft off, you'll lose oil.

Plus on the new unit is that you can remove your driveshaft and not lose oil because the tailshaft remains sealed. The minus of course is the more exposed lenght of tailshaft...

Somewhere along the line there was also a change in manufacturer, from New Process to New Venture (NP231 vs NV231)...

Ivan

Wasn't really a change in manufacturer. It's the same company -- they just changed the name on the door.

Ivan said:

Plus on the new unit is that you can remove your driveshaft and not lose oil because the tailshaft remains sealed. The minus of course is the more exposed lenght of tailshaft...

Click to expand...

The other minus to that "upgraded" transfer case is that the 96+ NP/NVG-231 t-cases are more prone to vibrations with minor lifts, some Up-Country Jeeps apparently had vibes straight from the factory due to the whopping inch taller in that configuration.

he's blowing smoke up your a$$, plain and simple.. operationally and for all practical purposes its the same unit.. a salesman wont talk to you about how easy it is to modify.. just how easy to use.. all he has to say is "upgraded" and most people will just think it's better and move on to talk about the color.. now with that being said, the input shaft spline count also changed.. from 27 to 23 or 23 to 27.. not sure and i dont feel like going out to the trail rig to look at my spare with a flashlight tonite..
mike

And the winner is...

Okay, here's the skinny, I checked with a different salesman, who incidentally has a stoked ZJ, and this XJ has the "select-trac" not the "command-trac" as the previous salesman had stated. For an XJ, this one is pretty cushy.

Thanks for all the information!

4wd system question

Somebody please point me in the right direction for the ultimate explanation of the differences between "command Trac", "Select Trac" and "Trac Loc" I am tired of just nodding my heading and trying to look like I know what the hell people are talking about when they start these philosophical discussions about transfer cases and 4wd systems. Thanks in advance for the direction. I have the smaller of the two transfer cases which I believe is the NP 231 on my 88 and what I think is the "Select trac" system but I don't really know............yet

Re: 4wd system question

gettinbetterXJ said:

Somebody please point me in the right direction for the ultimate explanation of the differences between "command Trac", "Select Trac" and "Trac Loc" I am tired of just nodding my heading and trying to look like I know what the hell people are talking about when they start these philosophical discussions about transfer cases and 4wd systems. Thanks in advance for the direction. I have the smaller of the two transfer cases which I believe is the NP 231 on my 88 and what I think is the "Select trac" system but I don't really know............yet

Click to expand...

Command-Trac and Selec-Trac are the two transfer cases. As noted above, Command-Trac is the base level. Has 2WD, 4wdHi, N, and 4WD-Lo. Both 4WD positions lock the front and rear drive shafts, so turns on hard pavement cause binding in the drive train. That's why it is listed for "Part-Time" use only.

Selec-Trac has all the above positions, plus an additional Full-Time 4WD position. This is a high range position that uses a differential within the transfer case to unlock the front and rear drive shafts. In the Full-Time position, you can use 4WD on pavement -- including dry pavement.

Trac-Lok is Jeep's (and Dana Spicer's) name for the optional limited slip rear differential available on XJs. It's a clutch type limited slip, not considered very aggressive, but virtually transparent on the road. It's not for hard-core stuff, but I think it gets a bad rap.

thanks a ton Eagle, very helpful as always!

Eagle,

Is there something in the VIN (or elsewhere) that provides the ability to quickly determine if an XJ has Command Trac or Selec Trac (other than the xfer case shifter)?

Also, doesn't the xfer case designation change to 232 (or 242) with Selec Trac (due to the additional internal diff)?

Thanks, Dave.

I don't know if the VIN has a code for transfer case. Easiest way to tell is look at the shifter bezel -- or flip down the driver's sun visor and read the sticker.

The Command-Trac is an NP (or NVG) 231. Selec-Trac is 242. XJs prior to 1987, however, used a 207 for Command-Trac and a 228 or 229 for Selec-Trac.

Just when I thought I knew everything............(Yeah sure.....) What the heck then is the "Smart Trac" like you find on my neighbors Oldsmobile Bravada?

Eagle, MJs got Trac-Lok too...

I've had 3 of them.
Currently have 1 of those 3.

The 228/229 Selec-Trac had a seperate switch for 2WD/4WD selection.
These being found on 1984-1986 XJs.
MJs never got Selec-Trac.
Although...perhaps I should try that...
I DO have a 90 XJ Limited donor vehicle w/ a good 4x4 driveline...which has the 242.

The 242 doth not have the 2WD/4Wd switcheth. Narf.

Eagle, Selec-Trac in an MJ? Good idea?
My 90 is a 5 speed, so I'll have to find an AW4 MJ.


Teron :angel:

gettinbetterXJ said:

Just when I thought I knew everything............(Yeah sure.....) What the heck then is the "Smart Trac" like you find on my neighbors Oldsmobile Bravada?

Click to expand...

It's Oldsmobile's name for all-wheel drive. I'm not sure if it's full-time or if they call it "smart" because it engages progressively as it detects speed differences between front and rear. The Bravada does not have a low-range in the transfer case. It's intended as a grocery getter.