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  #25  
Old 08-04-2010, 02:24 PM
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Re: Overland QTII, Select Trac, & Quadra Lift confusion.

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Originally Posted by Sir Bean View Post
Just wanted to confirm with you saying that QTII is not part time. According to the WK2 website, it states for the QT II:
  • Operating positions: 2WD - 4WD Auto N 4WD Low.
  • 2WD = 2 wheel drive.
  • 4WD Auto = Electronically controlled wet clutch for torque biasing.
  • N = Transfer case neutral for 4-wheel flat recreational towing.
  • 4WD Low = Low range (2.72:1) part time mode.
Another thought, do you have to have it in 4WD Auto to get the torque bias of the select terrain?

I now know that QDII is full time. But the question I still have is with the QDII front axle, is traction control via brakes like QTII?
There's no way to select 2WD on any Grand Cherokee. There's simply no selection lever, button, or dial. The only thing similar would be the Selec-Terrain knob, and the closest you will get will be the "Sport" mode which is still a 20/80 front/rear split at most (it could be less, depending on conditions).

I would anticipate part of the traction and stability control would utilize the brake at each wheel, although I do not know this for sure. It's a poor man's workaround for a real limited slip differential, but it's good enough for lousy weather. For the QDII front axle, I would anticipate that not having the ELSD means the brakes are going to fake it.
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  #26  
Old 08-04-2010, 03:42 PM
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Re: Overland QTII, Select Trac, & Quadra Lift confusion.

In my experience the difference between traction control and limit slip differentials is mostly in smoothness. *If one wheel is slipping, a limited slip differential will tighten up and begin to turn both wheels instead of sending all the power to the slipping wheel. *Electronic limited slip differentials can do this so quickly and smoothly that it may seem like a low traction situation was never even an issue.

Traction control systems apply the brake briefly to the spinning wheel, instantly but briefly transferring all power to the non spinning wheel. *This works out fantastically if one wheel has excellent traction, but in a sitaution where both wheels are on a slippery surface the sudden power transfer can often cause the non spinning wheel to break loose.
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  #27  
Old 08-05-2010, 09:46 AM
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Re: Overland QTII, Select Trac, & Quadra Lift confusion.

This is one of the bigger mysteries about the WK2 selections. QTII with the dial is available as a choice with the off-road packages regardless of the suspension choice. QuadraLift gives you variable ride heights, so does that make it Select Terrain II??? Obviously not, but the combinations get to be a bit much when speaking about those systems.
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  #28  
Old 08-05-2010, 10:43 AM
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Re: Overland QTII, Select Trac, & Quadra Lift confusion.

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Originally Posted by Jim Hef View Post
This is one of the bigger mysteries about the WK2 selections. QTII with the dial is available as a choice with the off-road packages regardless of the suspension choice. QuadraLift gives you variable ride heights, so does that make it Select Terrain II??? Obviously not, but the combinations get to be a bit much when speaking about those systems.
Selec-Terrain is nothing more than Selec-Terrain. It is a method by which you can tell the vehicle computer what kind of terrain to expect; if in sport mode, you're telling it you aren't leaving pavement. In in rock mode, you're telling it that you're heading off into the boonies.

Then the vehicle computer does what it needs to do with whatever else is installed. If Quadra-Lift is installed, it will make use of its capabilities. If not, then it won't.

Ditto the QTII and QDII systems; the vehicle computer will utilize whichever you have in the most advantageous manner for whatever you have selected.

You're seeing these as more specially integrated than they are. They interact, but they aren't necessarily that closely married to where the existence of a different component (say, QDII in place of QTII or the existence of QL at all) makes Selec-Terrain that much different. It's just a means by which you tell the computer what you're going to be doing.
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Old 08-18-2010, 11:57 PM
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Re: Overland QTII, Select Trac, & Quadra Lift confusion.

How will the ELSD-less front diff of the WK2 handle driving up a slippery road? Will it actually send brake signals to a wheel in motion? That would suck balls. I would much rather have power going to both wheels that may or may not spin instead of braking being sent to one so they other might be able to help. That does not sound like any form of QD that jeep has ever released. Even my 2002 jeep has a better system.
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Old 08-19-2010, 09:26 AM
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Re: Overland QTII, Select Trac, & Quadra Lift confusion.

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Originally Posted by Technosavant View Post
...You're seeing these as more specially integrated than they are....
Not really! With QL added, the suspension travel comes into play, so they are fully integrated. That was the point of my original post. I do agree with one of your other comments though...I will probably select Sport for on-road travel most of the time, and allow the vehicle to hunker down a bit.
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Old 08-19-2010, 09:29 AM
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Re: Overland QTII, Select Trac, & Quadra Lift confusion.

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Originally Posted by Jeff_Jeske View Post
...I would much rather have power going to both wheels....
Limited slip doesn't work that way, but a locking differential would. LS throws power from one side to the other depending upon which wheel is slipping. So, until some tests show how the braking technique works for both QTII and QDII, we won't really know how effective this is. Most of the German stuff has brake application limiting, and they work quite well.
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Old 08-19-2010, 05:48 PM
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Re: Overland QTII, Select Trac, & Quadra Lift confusion.

My take on an LSD is it pretty much locks both wheels together. It prevents one from spinning out of control by sending power to both sides.

QD claimed to have the ability to send all the power to one wheel but not by use of brakes. I don't think it really works the way they claim and I'd rather have a 50/50 split with mechanical front and rear LSDs.
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Old 08-21-2010, 07:25 AM
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Re: Overland QTII, Select Trac, & Quadra Lift confusion.

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Originally Posted by Technosavant View Post
... There's simply no selection lever, button, or dial. The only thing similar would be the Selec-Terrain knob, and the closest you will get will be the "Sport" mode which is still a 20/80 front/rear split at most ...
So...does this mean that the optimum highway driving Select-Terrain setting for optimum fuel economy is "Sport"?

Thanks all for a very educational thead.
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  #34  
Old 08-21-2010, 09:02 AM
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Re: Overland QTII, Select Trac, & Quadra Lift confusion.

I don't think you'll notice any mileage differences in the various 'normal' modes. Sport, coupled with QL dropping the vehicle an inch or so may show a bit on a long trip at cruise speeds.
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  #35  
Old 08-21-2010, 09:07 AM
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Re: Overland QTII, Select Trac, & Quadra Lift confusion.

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Originally Posted by dmcjjeep View Post
So...does this mean that the optimum highway driving Select-Terrain setting for optimum fuel economy is "Sport"?

Thanks all for a very educational thead.
As said, I wouldn't expect a difference in the fuel mileage. Once you get to 60mph (in the neighborhood where the drag from the higher suspension settings would become an issue), the "Auto" selection will automatically lower the vehicle to the aero ride height.
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  #36  
Old 08-21-2010, 09:34 AM
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Re: Overland QTII, Select Trac, & Quadra Lift confusion.

Thanks for the replies, but my question is more focused on the "sport" setting and the 20/80 split.
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