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  #25  
Old 11-10-2010, 08:00 AM
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Re: Locking the center differential

Quote:
Originally Posted by xjman View Post
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.
Thanks. That's the info I was trying to find. It seems very similar to the 4Runner's system, except that the 4Runner uses a Torsen center differential that also provides a mechanical lock in 4HI or 4LO.

But back to my original question--- why wouldn't Jeep make the center diff lock available on 4HI in the Grand Cherokee?
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  #26  
Old 11-10-2010, 10:12 AM
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Re: Locking the center differential

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Originally Posted by MSCA View Post
Thanks. That's the info I was trying to find. It seems very similar to the 4Runner's system, except that the 4Runner uses a Torsen center differential that also provides a mechanical lock in 4HI or 4LO.

But back to my original question--- why wouldn't Jeep make the center diff lock available on 4HI in the Grand Cherokee?

Same topic posted earlier in response to your question. In what driving conditions do you feel you need 4Hi with a lock, and why?

A lock doesn't help in snow at moderate to higher speeds, as those conditions typically include cornering and turning. As others have stated here, even 4 low is rarely needed in big snow, and if it is, it's at low speeds or getting unstuck.
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  #27  
Old 11-10-2010, 10:28 AM
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Re: Locking the center differential

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Originally Posted by moosehead View Post
Same topic posted earlier in response to your question. In what driving conditions do you feel you need 4Hi with a lock, and why?

A lock doesn't help in snow at moderate to higher speeds, as those conditions typically include cornering and turning. As others have stated here, even 4 low is rarely needed in big snow, and if it is, it's at low speeds or getting unstuck.
I explained earlier that I'd prefer to be able to lock the center diff in 4HI in order to get up to my winter cabin. If you could see the uphill offroad path that leads to the cabin, you'd understand why it would be virtually impossible to make it up to the top in 4LO when there's snow on the ground. I need to keep a decent amount of speed and momentum to even have a shot at making it up. There's simply not enough traction to do it at the low speeds required in low gear. Besides, the extra torque multiplication in 4LO makes it even easier to spin the tires in snow and break traction, which is the last thing I need to do on that hill!

My 4Runner is one of the only vehicles I've ever owned that can consistently make it up the hill in the winter and without locking the center diff, even my 4Runner doesn't have much of a chance making it up.
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  #28  
Old 11-10-2010, 10:55 AM
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Re: Locking the center differential

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Originally Posted by MSCA View Post
I explained earlier that I'd prefer to be able to lock the center diff in 4HI in order to get up to my winter cabin. If you could see the uphill offroad path that leads to the cabin, you'd understand why it would be virtually impossible to make it up to the top in 4LO when there's snow on the ground. I need to keep a decent amount of speed and momentum to even have a shot at making it up. There's simply not enough traction to do it at the low speeds required in low gear. Besides, the extra torque multiplication in 4LO makes it even easier to spin the tires in snow and break traction, which is the last thing I need to do on that hill!

My 4Runner is one of the only vehicles I've ever owned that can consistently make it up the hill in the winter and without locking the center diff, even my 4Runner doesn't have much of a chance making it up.
I get it, having lived in upstate NY and skiing the NE for many seasons, those conditions are tough. No need to play the "my hill is steeper, snowier, tougher than your hill" game. In that regard, I'd probably put the Cascade's or Sierra's as toughest snow conditions.

All that said, the Jeep should get you up that hill 98% of the time in either 4Hi or 4Lo, and as nicely as the 4Runner. My guess is that the other 2% of the time, conditions are either sustained packed, icy conditions, or extremely deep, unplowed snow. In those cases, studded snows may be the answer, or maybe hiking up.

How often are you exceeding 15-20mph in order to plow uphill?
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  #29  
Old 11-10-2010, 11:14 AM
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Re: Locking the center differential

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Originally Posted by moosehead View Post
I get it, having lived in upstate NY and skiing the NE for many seasons, those conditions are tough. No need to play the "my hill is steeper, snowier, tougher than your hill" game. In that regard, I'd probably put the Cascade's or Sierra's as toughest snow conditions.

All that said, the Jeep should get you up that hill 98% of the time in either 4Hi or 4Lo, and as nicely as the 4Runner. My guess is that the other 2% of the time, conditions are either sustained packed, icy conditions, or extremely deep, unplowed snow. In those cases, studded snows may be the answer, or maybe hiking up.

How often are you exceeding 15-20mph in order to plow uphill?
Yeah, that's exactly the problem. It gets a bit bumpy at certain points, but I need to keep my speed up around 20 MPH or better to make it. Certain sections are rougher than others, so I can't exactly do 30 MPH all the way up, but if I drop to 10 MPH or less, I'm definitely dead in the water and will have to back down to the bottom to try again. I've been through that drill a few times before. My cousin is also very familiar with backing down and trying again with his TrailBlazer. He almost never makes it up there in the winter, but he's always willing to try.

Hiking up would suck because you'd have to carry all your gear and it's even difficult to walk up when the conditions are slippery! One year we brought some wood for the stove in an old pick-up bed-mounted toolbox and ended up having to create a make-shift sled to pull it up the trail. We found the hood from an old van in the woods and some rope and put the toolbox on top to get it to the cabin. It sucked pretty bad. LOL
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  #30  
Old 11-10-2010, 11:22 AM
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Re: Locking the center differential

Here ya go...found a pic from that day. Funny stuff!
Attached Images
File Type: jpg PKB.JPG (63.9 KB, 42 views)
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  #31  
Old 11-10-2010, 11:27 AM
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Re: Locking the center differential

sounds to me like you need to do some road work....LOL
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  #32  
Old 11-10-2010, 01:38 PM
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Re: Locking the center differential

Yeah, it's not even a road. It's basically a trail that's wide enough for an SUV. That picture was taken in a portion where it's almost level....and it goes up pretty steep most of the way.
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  #33  
Old 11-10-2010, 08:53 PM
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Re: Locking the center differential

The WK2 does not have a center differential in the normal sense. The transfer case just has a clutch that can be "locked" up to the capacity of the clutch. Torque is always sent to the rear wheels and the clutch is engaged to send torque to the front. In 4wd high range, the amount for force applied to the clutch is varied as needed. In 4wd low range, the clutch is essentially "locked" but it is true that at some point it will slip. It is very likely that other things may go wrong before this happens.

The WK has a transfer case with an open differential (48/52 split) and a clutch that is used to control slip across the clutch. In 4wd low range, the clutch is "locked" up to the capacity of the clutch.
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Old 11-10-2010, 09:40 PM
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Re: Locking the center differential

Ever considered chains for all four wheels? Might be your best option. If only two chains...put 'em on the fronts....what I was always told. Then 4 Lo is a cake walk.

Once chained all 4 wheels on my old suburban when getting out of an elk hunting camp in Idaho. Pushed snow with the front bumper for almost 30 miles to get to the main hiway. Some curves on mountain roads scared the spit outta me....but I had my elk loaded and the rack on the roof. Big blizzard all the way though the mountains and all the way back to MN. Listend to the Twins win the World Series while driving over the mountains with chains. What a trip.
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  #35  
Old 11-10-2010, 09:51 PM
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Re: Locking the center differential

Trust me, from your picture it seams like my driveway is a little bit steeper. If my low sitting MKZ with pissy tries can get out of my drive way, your WK2 shouldn't have any problems even from a dead stop. I would suggest snow tires but then again, I would suggest snow tires to anyone that lives in an area were you get a lot of snow.

THis is a picture of my driveway, trust me, your WK2 will be able to get out. I'm even willing to bet that you can get out using "auto" mode.
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Old 11-10-2010, 10:00 PM
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Re: Locking the center differential

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Originally Posted by Knightrider03m View Post
Trust me, from your picture it seams like my driveway is a little bit steeper...
You missed the post where he says that most of that path is much steeper than the photo (it is almost level in the photo). And it is not a road but dirt path if I understood correctly
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