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Discussion Starter · #1 ·
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?
 

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if you get into the twisties with the quadradrive system, the rear wheels will have the first shot at getting traction. If one of the rears starts to spin while the other has traction, the varilock diff *should* start to lock up after a few wheel rotations of the spinning wheel. After that, if both rears are spinning, the t-case clutch should start to lock up and get the fronts spinning and the front diff should then act similar to the rear. It requires a bit of wheel spin to get both diffs locked up and working. Unless you have way oversized/heavy tires (or worn out clutch packs or too much friction modifier fluid in the varilock diffs), the system should work well.

If you have a non-varilock rear diff, I'd think the transfer case would still work since your rear driveshaft would be spinning faster than the front if the rear axle doesn't have traction on either tire, so really the only way to tell if you do have a varilock diff in the rear would be to open it up to look, or put the jeep up on jack stands and try to rotate one of the rear wheels by hand. If it begins to lock up after a couple rotations (you can definitely tell if the system is working correctly), you have a working varilock. If it doesn't lock up, you may have a non-varilock diff or a varilock diff that is worn out or with too much friction modifier and no longer works.

If it were me, I'd try putting it on jack stands and spinning the wheels by hand. If the rear doesn't lock up, I'd probably just open the rear diff to see what's in there and do a fluid change while I was at it. I suppose there may be a way to tell if you have the vari-lock diff by peeping through the diff cover fill hole too if you knew the visual differences between the setups.
 

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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.
 

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Discussion Starter · #5 ·
I bought mine with 99k from a single owner fully stock. So eaven if the rear diff was mistakenly put on from a non quadradrive wj, the front one should work properly correct, both front should spin for example if i was at a twistie?
 

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Yes, worst case, if you did have an open rear diff (someone took out the varilock rear diff), the tcase should still be trying to spin the front driveshaft and front diff assuming the tcase is working properly. Assuming your front diff is working properly, it should lock up if either of the 2 front wheels start spinning. That's the kicker with this quadradrive system; either diff or the tcase could each wear out if it's used hard or neglected for a long period of time. Even running slightly mis-matched tire sizes can rapidly wear the diffs out.
 

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it looks like your tires are getting stuffed pretty far into the wheel wells; are you sure they're not catching on the jeep's body and that's keeping the stuffed ones from rotating properly? if you don't have bump stop extensions, I'd think about investing in some as they'll keep your tires away from the body a bit.

Aside from that and assuming the tires aren't caught on the body, in a properly working system both of those rear tires should keep spinning if you keep steady on the gas.
 

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Discussion Starter · #15 ·
Will the tires stuffed in to the body will keep them from rotating, i will assume the power of the engine is very strong, that shouldnt stop them, dont you think? Also im going to send you a video from the same spot but from a year ago, dirt wasnt too loose, made it good.
 

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the engine is strong, but having that back right tire stuffed and making a lot of contact with the body could help the obstacle overpower the varilock diff. I'm not 100% sure that is what's happening, but I do hear the back right tire crunch into the body a good bit when you get stuck at the 15 second mark of this vid:

Again, assuming that isn't contributing to the issue, I'd still put it up on jack stands and try to spin one of the tires by hand. If it locks up at all, you have varilock and maybe just need a fresh diff oil change with the proper amount of friction modifier; maybe whoever did your axle/diff swap just put too much in to keep it from groaning during tight turns and that's making the varilock slip too much.
 

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Discussion Starter · #19 ·
These last 2 videos i send you are from a year ago. Between the first 2 videos i sent you and these last 2, i went off roading maybe once. I hope it just needs a fluid change. Now my last question to you is this, if you look and hear the tires on the very last video is that the quadra drive kicking in after you hear the tires spin couple times? Then it sounds like it grabs, if it is i believe thats how quadradrive should perform.
 
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