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  #13  
Old 11-08-2010, 10:49 PM
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Re: Locking the center differential

Unfortunately, the 3.06 gears are a bit tall for serious climbing.
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  #14  
Old 11-08-2010, 11:16 PM
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Re: Locking the center differential

the 3.06 is in the 3.6 right? You cant get the qd2 without the V8 and the 3.47
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  #15  
Old 11-09-2010, 06:38 AM
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Re: Locking the center differential

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Originally Posted by Scottina06 View Post
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.
Are you sure about that? On Jeep's website, it says the center diff is locked in 4LO. If that's true, then it should be evenly dividing power between the front and rear axles.

That's why I'm asking about this....I might need the center diff locked to make it up. And if I can only lock it in 4LO, it will be difficult to keep speed/momentum to make it up all the way.
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Old 11-09-2010, 06:41 AM
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Re: Locking the center differential

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Originally Posted by xmonger View Post
The transfer case (QTII/QDII) acts like a limited slip diff. Not a true lock but not open either.
Is it acting as a limited slip or is it using some sort of traction-based braking control to transfer power front/rear?
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  #17  
Old 11-09-2010, 09:56 AM
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Re: Locking the center differential

Do you have Selec-terrain? I'm presuming the ctc 'locks' to maintain the torque distro 50/50 in snow mode?

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Old 11-09-2010, 10:15 AM
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Re: Locking the center differential

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Originally Posted by MSCA View Post
Is it acting as a limited slip or is it using some sort of traction-based braking control to transfer power front/rear?

its limited slip in the rear....but it transfers torque front/rear using a gerator pump. The QD2 system does not have a locker at all. It cannot lock traction to either front or rear tires. Personally, I think it's essentially a useless feature without having either a front or rear locker, also locking the center diff will split the power/torque 50/50 between the front and rear axles. This is all well and good until one wheel looses traction on both axles as in snow on steep grades.
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  #19  
Old 11-09-2010, 10:53 AM
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Re: Locking the center differential

I have never heard of the JGC having a lockable center diff (which is different than a transfer case). There are optinal front and rear E-lock setups on some models (which I don't know are still offered), and also the limited slip rear diff setup.
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Old 11-09-2010, 10:59 AM
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Re: Locking the center differential

oops.. sorry.. tc.. getting my terms mixed up.
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Old 11-09-2010, 10:44 PM
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Re: Locking the center differential

That is not the way I understood the system.
The differential is open most likely the same type used in the NV242 select track, a thick disk looking piece with center and planetary gears.
The NV245 adds an electric clutch to the open diff system that allows the front and back to act as limited slip between front and back.
Unfortunately no salesman knows enough for more accurate description and the description on the Jeep web site is mostly useless.
My opinion, even in High the clutch will engage. Clutches don't lock, the are limited slip and that's why a special fluid is required for the NV245, because the clutches slip.
I think that the lock feature in Low means mechanical lock up just like the SelecTrac Part Time mode in the NV242.
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Old 11-10-2010, 12:06 AM
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Re: Locking the center differential

http://www.allpar.com/model/jeep/gra...okee-2005.html

"The heart of the system is the NV245 active transfer case. This transfer case includes a center differential coupled with an electronically controlled clutch pack, varying it from a completely open state to completely locked, and infinite possibilities in between. The 4-Low gear ratio is 2.72:1."

So the center differential goes from completely open to completely locked according to the electronic clutch.
I cannot find anything about the Low lock but I am willing to bet that in Low, it locks mechanically.
I say this because I read somewhere that the NV245 was based on the NV242 and I have some familiarity with the NV242. I could be wrong of course.
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Old 11-10-2010, 07:49 AM
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Re: Locking the center differential

Quote:
Originally Posted by Scottina06 View Post
its limited slip in the rear....but it transfers torque front/rear using a gerator pump. The QD2 system does not have a locker at all. It cannot lock traction to either front or rear tires. Personally, I think it's essentially a useless feature without having either a front or rear locker, also locking the center diff will split the power/torque 50/50 between the front and rear axles. This is all well and good until one wheel looses traction on both axles as in snow on steep grades.

That's why I'm asking about the center diff. If it is locked, then the power should be split 50/50 front & rear. And then traction control should transfer power from side to side on both front and rear axles. That's how my 4Runner's 4wd system works. Plus the center diff lock works in both 4HI and 4LO, so it is really excellent in snow.
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Old 11-10-2010, 07:53 AM
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Re: Locking the center differential

Quote:
Originally Posted by scjeep4.7HO View Post
I have never heard of the JGC having a lockable center diff (which is different than a transfer case). There are optinal front and rear E-lock setups on some models (which I don't know are still offered), and also the limited slip rear diff setup.
Right. If you have a center differential, then you can drive in 4wd on dry roads. If you just have a plain old transfer case, then you cannot.

Maybe that's where my confusion starts. My 4Runner has a transfer case and a fully lockable center differential. I thought the Grand Cherokee was the same set up. But now I'm not so sure. I'm pretty sure that QTII and QDII 4wd systems have both a transfer case (they both have low gear) as well as a center differential, right?
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