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  #13  
Old 09-13-2012, 10:45 AM
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Re: Quadra Drive II vs. Quadra Trac II

The only difference I have noticed is the QDII seems to react to wheel slip a little quicker than QTII. Now the comparison was 2003 (QTII) vs 2011 (QDII). Both systems work well though.
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Old 09-13-2012, 01:53 PM
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Re: Quadra Drive II vs. Quadra Trac II

What can a QDII do that a QTII can't?
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  #15  
Old 09-13-2012, 02:29 PM
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Re: Quadra Drive II vs. Quadra Trac II

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Originally Posted by Joche26 View Post
What can a QDII do that a QTII can't?
Gives you more power for tight spots, and spins the wheels much less. If you never run into situations where QD is a benefit, the QDII and QTII fitted into the WK2 work the same (they use the same transfer case).

QD adds a limited slip/locking differential to the rear end to limit spin instead of the relatively inefficient brake traction control. Brake traction control requires wheel spin to work, where the differential spin control usually does not. The end result is much less wheel spin, which is nice on snow or a gravel covered hill climb, and a bit more HP available to power through a rough spot or up a hill.

So, given the same driver skill and otherwise identical trucks, there may be severe situations where a QTII Jeep will be bogged down or stuck, but the QD Jeep will not. There will be plenty of situations, like shown in the video, where there is a bunch of QTII tire spin and pauses but the QD will just motor through smoothly.

The QD system has changed over the years more than brake traction control, the electric models in the current WK2 is more responsive than the older hydraulically actuated. Just saying that you need to consider those changes when discussing how well QD performed in the past.
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  #16  
Old 09-16-2012, 10:25 PM
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Re: Quadra Drive II vs. Quadra Trac II

Thanks fdjkvc your vids were good. I found another video people might find interesting because it compares qd2 and qt2 on the same maneuver.
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  #17  
Old 09-16-2012, 11:35 PM
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Re: Quadra Drive II vs. Quadra Trac II

Impressive demonstration. The video really shows the differences between QTII and QDII. I wonder why QDII is only available with the larger engine? Does limited slip require more horsepower to perform?
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  #18  
Old 09-17-2012, 07:45 AM
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Re: Quadra Drive II vs. Quadra Trac II

Great video.
One thing it doesn't show is a wk2 with QDII. The wk with QDII performed really well but now that Jeep have dropped the front ELSD for the wk2 with QDII I'm really keen to know for sure how much of a disadvantage that is...
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Old 09-17-2012, 12:58 PM
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Re: Quadra Drive II vs. Quadra Trac II

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Originally Posted by talon38c View Post
Impressive demonstration. The video really shows the differences between QTII and QDII. I wonder why QDII is only available with the larger engine? Does limited slip require more horsepower to perform?
Just marketing, wasn't always like that. Perhaps Jeep marketing found that there was so little demand for a V6 QD that it was not worth the effort. There is not that much demand for the QD to begin with, kinda expensive and requires special dif oil and more routine maintenance. Their studies probably show that folks that want uncompromised traction also want uncompromised power.... or that QD guys will pay top dollar, so force them to also spent the money on the more profitable V8...

Its just marketing...
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Old 09-17-2012, 01:07 PM
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Re: Quadra Drive II vs. Quadra Trac II

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Originally Posted by Brett View Post
Great video.
One thing it doesn't show is a wk2 with QDII. The wk with QDII performed really well but now that Jeep have dropped the front ELSD for the wk2 with QDII I'm really keen to know for sure how much of a disadvantage that is...
When we asked awhile ago, Jeep engineering said the WK2 traction computer is so much more processing power (quicker response) and with updated algorithms that front ELSD is of insignificant benefit, not worth its disadvantages. You may notice the QT WK2 spinning tires a little less than than the QT WK in that video. So you would expect the front tire of the QD WK2 to continue to rotate while its off the ground, but there would be little or no wheel spin for those tires on the ground. The WK2 QD should handle that situation a little less dramatically than the WK QD. But as the video says, all the systems got the Jeep though that obstacle. I think for aggressive rock crawling you'd want lockers front and rear, but then you are in a Wrangler anyway.
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Old 09-17-2012, 10:35 PM
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Re: Quadra Drive II vs. Quadra Trac II

I thought ELSD and "electronic locking diff" are a marketing way of saying "open diff with brake assist".

I have seen this in street cars and on a track, for example, those using brakes to turn and power out will be using their rear brake pads down faster.

I too can't really get a good answer to how the QDII is different than the open rear diff when both can shift power to "any wheel" using brakes. But as posted above, I think it has to do with TC (which sucks off road) and how the car limits power and brakes spinning wheels.. All of this is neat computer wizardry, but a cheap work-around to real LSD's and lockers... and probably prone to electronic gremlins right when you don't need them. .. My 2c.
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  #22  
Old 09-18-2012, 02:18 AM
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Re: Quadra Drive II vs. Quadra Trac II

Quote:
Originally Posted by comnjeep View Post
I thought ELSD and "electronic locking diff" are a marketing way of saying "open diff with brake assist".
The rear ELSD used by QD2, the Eatons EGerodisc "is a hydraulically-operated electronically controlled limited slip differential that provides variable torque up to full axle lock" (quote from eatons website). So it's quite different to the open diff used on the front axle (both front and rear for QT2). Looks like Jeep are using the term BLD (bake lock differential) with reference to the open diffs which is as you describe...

In the wk with QD2 the ELSD was fitted to both front and rear but with the wk2 it is rear only. They reckon the BLD on the front is almost as good. If this is really true then why even fit the ELSD to the rear? I suspect there are sales/marketing reasons at play, and that the ELSD are still better. However as the processing power of the onboard controller for the BLD improves (as apparently it has given a big improvement bewteen wk and wk2 QT2) makes me wonder if in the not-too-distant future there really will be little advantage to the ELSD...
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  #23  
Old 09-18-2012, 07:45 AM
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Re: Quadra Drive II vs. Quadra Trac II

comnjeep you may be hearing ELSD where they are saying brake traction control or ESC or simply traction control.

By the way, the WK2 uses an electric motor now to operate both the transfer case and differential clutches, not the hydraulic pump they have been using for a few years. The hydraulic system needed a bit of wheel spin to get going, annoying the heck out of a few trail riders. The WK2 computer is programed to anticipate tire spin, so the response is instantaneous in most conditions.

ESLD will always have the advantage of getting more power to the ground and less wheel spin. Brake traction converts a lot of power to heat along with wearing out the brakes. Ok for light duty, not so good for heavy duty. Since the rear axle is doing most of the push on up hills where you may need a lot of traction, ELSDs advantages will be felt most there.
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  #24  
Old 09-18-2012, 03:57 PM
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Re: Quadra Drive II vs. Quadra Trac II

WK2 with QD2 have ELSD in rear diff and BTC in front.
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