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-   -   Locking the center differential (http://www.jeepgarage.org/f73/locking-the-center-differential-14906.html)

MSCA 11-08-2010 02:27 PM

Locking the center differential
 
Do I have this right? Only QTII & QDII have a lockable center differential and the only way to lock it is to put it low gear?

Why can't the center differential be locked in high gear as well???

Technosavant 11-08-2010 04:23 PM

Re: Locking the center differential
 
There's no need to fully lock it in high range. The system itself handles the front/rear torque bias. If you're in a situation where a 50/50 split is going to make the difference, you may need to be thinking about low range anyway.

robpp 11-08-2010 04:54 PM

Re: Locking the center differential
 
just a bit of reality: I have driven my XJ for 132K over 12 Colorado winters. I have engaged LO 2 times.



so for the LO: its there, you'll know when you need it.

MSCA 11-08-2010 05:20 PM

Re: Locking the center differential
 
Quote:

Originally Posted by Technosavant (Post 298022)
There's no need to fully lock it in high range. The system itself handles the front/rear torque bias. If you're in a situation where a 50/50 split is going to make the difference, you may need to be thinking about low range anyway.

But the center diff is an open diff, right? From my understanding, an open center diff will not be able to transfer torque to the axle with more traction. It must use some sort of traction control system to transfer torque. My guess is that 4LO doesn't use any traction control and instead locks the center diff, right?

MSCA 11-08-2010 05:21 PM

Re: Locking the center differential
 
Quote:

Originally Posted by robpp (Post 298058)
just a bit of reality: I have driven my XJ for 132K over 12 Colorado winters. I have engaged LO 2 times.



so for the LO: its there, you'll know when you need it.

That's exactly my point. I hardly ever use 4LO, so why wouldn't I want the ability to lock the center diff while in 4HI? It just seems counter-intuitive to me. Other 4wd vehicles can lock the center diff in 4LO and 4HI.

chibianh 11-08-2010 05:25 PM

Re: Locking the center differential
 
Has Jeep's Quadra-trac system ever offered this? It was available on the selec-trac system our previous GC as part time 4wd, but i don't remember if Quadra-trac had this or not.

Marlin 11-08-2010 05:31 PM

Re: Locking the center differential
 
Yeah previous vehicles I've owned has allowed LOCK in both Hi and Lo range, and at times, I have found it usefull to have Hi-Lock abaility.

However, I don't think the JGC systems have ever had the feature?

And I've not missed it on my current WK. I think for most situations requiring only high range, the system does a fine job of finding traction.

MSCA 11-08-2010 05:35 PM

Re: Locking the center differential
 
Quote:

Originally Posted by chibianh (Post 298082)
Has Jeep's Quadra-trac system ever offered this? It was available on the selec-trac system our previous GC as part time 4wd, but i don't remember if Quadra-trac had this or not.


I'm not really familiar with Jeep's different 4wd systems, but I don't think even QDII has it. It seems to me that the vehicle must be in 4LO to lock the center diff.

I'm not sure that would work very well for getting me to my winter cabin. It's on an unmaintained road (it's actually not even a road) that is about 1/4 mile long and a fairly steep uphill rise. It's in upstate NY where there is snow all winter long. I need to keep a decent amount of speed and momentum to even have a chance of making it up in deep snow, and I'm not sure that would be possible if I had to be in 4LO to keep the center diff locked. Without the center diff locked, I not sure I could make it up at all.

chibianh 11-08-2010 06:12 PM

Re: Locking the center differential
 
QDII is just QTII with a rear ELSD. Looks like the only current Jeep system to have the ability to lock the center diff is one of the systems used in the Wrangler. Maybe the QTII center diff was designed this way because torque is already being distributed front/rear. Like Marlin mentioned, the system does a fine job (i've attested to this recently with QDII) so locking the center may not be needed.

xmonger 11-08-2010 09:45 PM

Re: Locking the center differential
 
The transfer case (QTII/QDII) acts like a limited slip diff. Not a true lock but not open either.

Knightrider03m 11-08-2010 10:17 PM

Re: Locking the center differential
 
When I had my ZJ, I used the AWD in light snow/ice, I used the 4WD lock in deeper snow (2-3 inches or more), used 4lo when I got stuck in the snow. I'm sure my AWD system could have been used for the deep snow but since I had the 4 lock, I just used that. In my MKZ which gave me no control on if the car was using all 4 of its wheels or not, the only time I got stuck was when I was on a sheet of ice with a 2-3 inch ice ball blocking my wheel but I was on a sheet of ice too so all 4 of my wheels was spinning and wasn't doing nothing. I plowed through 12-13 inches of snow, at one point I had to stop on a steep hill in that high snow to get out on to the main road and I was able to take off without no problems. With my Liberty, I do not have the ability to have it act as a AWD system so I will use my 4 lock for ice and snow and 4 low for if I get stuck in the snow. All of the times I got stuck in snow, it was due to be being a dumbass (I.E driving into plowed snow that was 2 feet or higher).

Scottina06 11-08-2010 10:20 PM

Re: Locking the center differential
 
the GC doesnt have a locking diff. The QD2 is considered by many to be the best 4wd system in the world. I dont think you will have any problem getting up that hill with the appropriate tires.


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