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Unread 02-23-2012, 09:55 AM   #1
Merkava
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Join Date: Feb 2012
Location: Thornton, CO
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QT2 and QD2 questions

First post!

I've been looking at getting a new grand cherokee and I've been reading about the QT2 and QD2 systems. I keep reading the only difference between QT2 and QD2 is the rear differential. But it seems that along with QD2 on a 2012 you will get Quadra lift as well. I'd like to get a slight lift kit/bigger tires and it sounds like Quadra lift will make that impossible. I've been leaning towards just getting QT2 and maybe putting a truetrac on the rear. If I understand the truetrac operation correctly and the way QT2 uses the brakes to control wheel spin it would seem the truetrac would multiply the torque from the braking to the wheel with better traction. So....

1. Is there no way to get QD2 without Quadra lift?
2. Do QD2 and QT2 have exactly the same front differential?
3. Am I right about the assumptions I made about the Truetrac and braking?

Thanks for your help.

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Unread 02-23-2012, 10:58 AM   #2
superserialMBP
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#1 is definitely true, there is no way to get QD2 without the Quadra-Lift system. If you are looking to lift it, don't get QD2. I'm not certain on the other two questions.
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Unread 02-23-2012, 11:55 AM   #3
mderick
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Yes this is a burning question for me as well.
I would love to have the upgraded rear diff, but do not want the Quadra-Lift.
One would have to think there would be a lot of folks wanting this combo...
curious.
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Unread 02-23-2012, 12:10 PM   #4
WvTaco
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all diffs are open unless u get a hemi with qd2, it is the only one with the elsd

a trutrack is a gear driven lsd. and it with the brake traction, it would take less strain off the brakes and apply more power to the other wheel given the tire doesnt lift.
a lsd requires friction to push power to the other side.
but with the brake traction, the jeep would be appling force to the lifted wheel ( making it to stop spin) and make the other work. i dont see a down fall of this. but before u drop money on the lsd try the stock system for a little run.
the stock system acts as lsds and do a decent job.
i say get motor of your choice. and qt2 and something like rocky road lift. and lsd front and rear would be great.
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Unread 02-23-2012, 04:03 PM   #5
ColdCase
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Quote:
Originally Posted by Merkava View Post
First post!

I keep reading the only difference between QT2 and QD2 is the rear differential.

1. Is there no way to get QD2 without Quadra lift?
2. Do QD2 and QT2 have exactly the same front differential?
3. Am I right about the assumptions I made about the Truetrac and braking?

Thanks for your help.
1 yes
2 yes as well as identical transfer cases
3 can you get a truetrac for the rear of the new WK2? It is a mercedes housing. You may have better luck scavenging the salvage yard for an 2011-2012 ELSD rear end and update the traction computer. It would perform better but at what $$$.

All WK2s have brake traction control, effective for slippery roads but it does rob some power and can be hard on the brakes (the brakes make heat). A limited slip or equivalent would get more power to the the wheel with traction. The QT II transfer case can supply 80-90% engine power automatically to the axle that has traction, near 100% when in 4 low. A limited slip or truetrac would provide about 80-90% of that to the rear wheel with traction where brake traction is about 50%. So if all the wheel are off the ground (or little traction) except one rear then you will get 65-80% of your engine power to the ground with a limited slip rear and 40-45% without.

There are other advantages and disadvantages to each system but they kind of wash out in comparison, and depend a lot on what kind of trail or ice riding you are doing..
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