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It's tough to tell, but it really looks like your front QD system is working in the second video you posted. In the last video, yes, it looks like that's about the right amount of wheel slip before the QD system kicks in. I had my QD WJ out just last weekend and definitely engaged QD on a few blue trails. It's a cool feeling when the clutches engage and you just start moving forward.

From what I've read (and I've read a lot), the QD system loses effectiveness once you go higher than 32" tires. You're pretty much right on target with your 255/75/17's. What happens with bigger tires is the ground is farther away from the axle with a bigger tire so when the ground is holding a wheel steady, it's holding the wheel steady with more force. This is why Greyhound busses have massive steering wheels...less driver fatigue. On one side you have the ground holding the wheel steady at the tread. On the other side you have the friction in the clutch disk system trying to turn the wheel. If the ground is holding the wheel steady with more force than the friction discs can overcome in the diff, the discs will start to spin against each other and this accelerates wear in the QD diff exponentially. It's not a matter of whether the engine has enough power. It definitely does. The engine will keep sending power, but the friction discs will spin before the tire does after you pass a certain tire size.

Did the shop that did your rear diff replace the whole axle? From what I've found, the QD differential is completely non-serviceable and the only way to repair it is to install a whole new carrier. The assembly seems to be about a thousand bucks new. If the shop pitched the QD carrier and put in an open carrier to save money (or a non-QD carrier from a junkyard non-QD WJ), you'd be effectively QD-less in the back. You could, however, have a real locker installed since the non-QD carrier will accept one.
 

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It's unlikely that a shop could just swap to an open carrier. I believe even the rear axles shafts are different lengths depending on if your diff is open or varilock.

When in doubt, do a fresh change as suggested and use genuine mopar 75w-140 diff oil with mopar friction modifier.
 

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Silver linings my guy! Like I said before, an open D44a axle can accept a REAL mechanical locker which is better than the vari-lock setup. Beyond that, the open D44a's are kinda tough to find since most V8 WJs came with QD, and you (may) already have one! I actually pulled one from a junkyard to fill with Spartan Locker and swap into my WJ. Ideally you want a 242HD t-case also, but if you don't DD it I think you'll be fine using the 247, at least until wheeling it wears the clutches out. Then you find yourself a 242HD.
 

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I don't think they swapped an open axle in. Like mentioned an open 44A is a pretty rare bird. If they tried to sneak a 35 in they would have to also swap gears, 35's are 3:55 geared where the 44A is a 3:73 no matter open or vari lok. My 04 rear vari lok is pretty weak as well, it will spin both in snow but in dirt I get more one wheel peel then 2 wheel turn, my front seems to be just fine though.
 

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2002 jeep Grand Cherokee 4.7
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Hi guys I have a question, I am a bit confused on how the Quadra Drive system works. I have a 2004 Jeep grand Cherokee Quadra drive and last year they replaced my rear differential with another one. Now that I’ve gone off roading going through twist only my front driver and rear passenger works, or vice versa depending on the twist. I’ve been thinking either they did not put a Quadra drive rear differential with a vari lock or the clutches went out. I’m inclining more that the clutches did go out, because lets say they did not install a Quadra drive rear differential, the front one is a Quadra Drive differential and both front tires should be spinning correct?
sound like they gave you and open differencial when you got the swap
 

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On my current, an '04, the Vari-Lok did not work in the rear when I bought it. Fluid change (AMSOIL Severe Gear 75w-140) and limited slip additive (AMSOIL Slip Lock) brought it back to life. To confirm operation, with the wheels off the ground turn one wheel, the other will turn in the same direction. However, unlike a Posi, it does not turn the same way direction right away - initially it will turn in opposite directions like an open diff. It may take an almost full revolution before it will change direction. Since my NV247 doesn't work in full-time 4wd, I confirmed my operation by way of a smokey 2 wheel burnout, because I am a child. 11's on the pavement = functional Vari-Lok. ;) :geek: Also, if you use Mopar diff fluid, it should have the additive already in it, but an extra 2oz doesn't hurt. In the case of a "burnt" Vari-Lok clutch, the extra additive can often shock it back to life.

There is also this thread that has a more thorough test for functionality: I need for clutch pack for WJ's rear Vari Lok

Side bar - I've heard limited slip additive can shock a burnt NV247 back to life as well, but in my case it must have been too late - when I changed the transfer case fluid it was full of black ATF that had probably been in there for 60k+ miles. Chrysler blew it on that one - with transfer cases before and after the NV247 using ATF, I feel like they should have put a "NO ATF" warning tag by the TC fill plug for dummies. Even the dealerships were dumping ATF in them.....
 
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Side bar - I've heard limited slip additive can shock a burnt NV247 back to life as well, but in my case it must have been too late - when I changed the transfer case fluid it was full of black ATF that had probably been in there for 60k+ miles. Chrysler blew it on that one - with transfer cases before and after the NV247 using ATF, I feel like they should have put a "NO ATF" warning tag by the TC fill plug for dummies. Even the dealerships were dumping ATF in them.....
ATF isn't bad for the 247, it just makes a lot of noise when cornering. The WJ was a high end soccer-mom-mobile when new. They didn't like the noises and vibrations, so Jeep spec'd a wet clutch fluid that is made for tractors, to quiet it down. The number one killer of the progressive coupler in the 247 is owners that ran slightly different size tires front and rear. (Often it was 2 brand new tires and 2 "not worn out yet!" tires). This would cause the driveshafts to rotate at different speeds all the time, thus engaging the coupler, but it couldn't force the front and rear tires to go the same speed on dry pavement and would slip like crazy on the highway. :( This would burn out the clutches, much like what happens to an automatic transmission that has run low on fluid. Once the clutches are burned out, they're useless.
 

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ATF isn't bad for the 247, it just makes a lot of noise when cornering
My understanding is that the noise is binding from the full-time 4wd clutch not slipping as it should when cornering. It does allow for slip when Mopar TC fluid or 5w-30 synthetic hydraulic fluid is used. I've also read the geo-rotor pump that operates the clutch doesn't like ATF and fails. Not stating as such as fact, but it is how I have come to understand it from what I read when trying to figure out why my "new" (now 2yrs ago) WJ didn't have full-time. I've looked at drawings, and watched rebuild videos, but I have not personally had one open so I can only go on what I've read. While it doesn't matter anymore as mine doesn't work and I've no intention of repairing, but I currently run AMSOIL 5w-30 Tractor Hydraulic/Transmission Oil, and 4oz of their Slip Lock friction modifier. That said, I still 100% agree that different sized tires will smoke a TC as well. I believe Chrysler said no more than 3/32" wear difference between front and rear....
 

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I guess I got lucky with mine. The PO said the 4wd never worked, I suspected the worse. Turned out to be a wrong axle shaft in the front, the wheels were never engaged. That I believe actually spared my t/case seeing the tires were very mismatched in size, luckily my t/case never knew the difference. I fixed the axle, drained the nasty case fluid and replaced with the special 247 sauce Mopar sells, it works great with some slight moaning when hard turning dead cold below freezing. It does engage quick, goofing around last night in front of a store front window I can say the front wheels getting powered is almost instant.
 
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I ran that size in mud terrains (32" JK Rubicon takeoffs) for over 7 years and I still run 32's (highway tread) to this day, and it hasn't caused any issues to my varilocks. We have kept up to date on fluids and maintenance since my family bought it new off the lot though.
Did you need a lift for the 32”? Thx!
 

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2002 jeep Grand Cherokee 4.7
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I ran that size in mud terrains (32" JK Rubicon takeoffs) for over 7 years and I still run 32's (highway tread) to this day, and it hasn't caused any issues to my varilocks. We have kept up to date on fluids and maintenance since my family bought it new off the lot though.
the BLACK WJ is so good looking.
 

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the BLACK WJ is so good looking.
+1. I LOOOOVE my Midnight Blue Pearlcoat. But had I bought it brand new back in 2004, Brilliant Black Crystal Pearlcoat with Sandstone leather is definitely what I would have ordered....
 
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