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  #13  
Old 08-29-2010, 07:22 AM
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Re: No front ELSD for QD II?

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Originally Posted by Jim Hef View Post
Quoting Jeep.com is not a good thing! They don't come close to keeping the specs current on their site, and usually have several discrepancies within the build section. Brochures are printed long in advance, so they are not accurate either...and possibly, for the same reason, the Owner's Manual! We know for a fact that the front was omitted, and it now just uses the braking application as the limiting device. What we are presently investigating, is what is the axle ratio for the various engines, with or without any Off Road package. The omission of the front LSD is one question I want to ask the engineers during the scheduled chat.
Thanks for the sad news, though Jeep.com did update some of the Build My Own section, such as available colors and options. But the mention of the two ELSDs is still there.

Dropping the front ELSD would invalidate their claim that full torque can be applied to any single wheel. Using the brakes is fine for stability control, but it will cut in half the torque available to the free wheel compared to what the ELSD could provide. Besides, they canít use the brakes for locking the axles in 4Lo range. For that a locker is needed and the ELSD used to do that. They had it there before. Is the cost saving worth Mickey-Mouseing what I thought was the perfect system? Go figure.
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  #14  
Old 08-29-2010, 09:26 AM
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Re: No front ELSD for QD II?

I heard it was a dispute with the supplier.
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  #15  
Old 08-29-2010, 10:51 AM
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Exclamation Re: No front ELSD for QD II?

I don't recall that the LSDs were any form of locker for the diffs, but simply a mechanism to transfer power side to side.
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  #16  
Old 08-30-2010, 07:31 AM
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Re: No front ELSD for QD II?

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Originally Posted by Jim Hef View Post
I don't recall that the LSDs were any form of locker for the diffs, but simply a mechanism to transfer power side to side.
As you know, the the term “Limited Slip Differential” refers to the slip between a set of friction plates that resist speed differences between the right and left axle shafts. By varying the pressure between these friction plates (ELSD), the strength of this slip resistance may be varied from zero (open diff) to rigid (locker). Between those extremes, more or less torque is transferred to the wheel with traction while the other spins freely. For the 2011 QDII to work as claimed, all three conditions (open, variable, locked) come into play. And, locking the differential (4Lo range) obviously cannot be accomplished with brake application.
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Old 08-30-2010, 07:44 AM
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Re: No front ELSD for QD II?

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I heard it was a dispute with the supplier.
I think you must be right. There is no technical excuse. Where/when did you hear this?
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Old 08-30-2010, 10:10 AM
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Exclamation Re: No front ELSD for QD II?

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...And, locking the differential (4Lo range) obviously cannot be accomplished with brake application....
I need to read up more on QDII as it's applied in the WK range vs the WJ. In my QD, 4Lo just locks the transfer case to a 50/50 split, and to my knowledge, does not affect the diffs, both of which are LSDs.
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Old 08-30-2010, 10:50 AM
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Re: No front ELSD for QD II?

there is no "locking" of the diff with a QD2. It provides power to the wheel with traction
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  #20  
Old 08-30-2010, 11:41 AM
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Re: No front ELSD for QD II?

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Originally Posted by Jim Hef View Post
I need to read up more on QDII as it's applied in the WK range vs the WJ. In my QD, 4Lo just locks the transfer case to a 50/50 split, and to my knowledge, does not affect the diffs, both of which are LSDs.
Your system has to use the brake to lock an airborne wheel in rock crawling, and that cuts in half the torque available to the wheel on the ground. With an ELSD you get full torque. That’s the elegance of the 2011 QDII as described on Jeep.com.
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  #21  
Old 08-30-2010, 11:45 AM
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Re: No front ELSD for QD II?

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there is no "locking" of the diff with a QD2. It provides power to the wheel with traction
For 2011 there is (supposed to be).
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Old 08-30-2010, 01:19 PM
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Re: No front ELSD for QD II?

The diffs in the original QD used hydraulics to engage, not a brake application. That is the system I refer to. I'll read what you have linked.

Ah, I see what you write about. While the audio doesn'ty mention it, the graphic seems to indicate that, while in 4Lo, the diffs are sending power to both wheels at each axle. I'd need to read more about this to ensure that it is indeed happening.
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  #23  
Old 08-30-2010, 04:00 PM
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Re: No front ELSD for QD II?

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Originally Posted by Jim Hef View Post
The diffs in the original QD used hydraulics to engage, not a brake application.
So they are actually self-locking LSDs. They take a bit of spinning for the Gerotor pump to pressurize the hydraulics. But you do retain full torque for the traction wheel. - I'm still hopeful about the front ELSD in the 2011 QDII. I've convinced my dealer that this is an important issue for him to resolve. He says he'll drill down through the service department tech contacts at Jeep. I'm curious about what will come of this, if anything.
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Old 08-30-2010, 04:20 PM
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Re: No front ELSD for QD II?

only the center diff locks in 4lo....not each axle
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