Front Axel Not Engaging - JeepForum.com
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post #1 of 11 Old 04-02-2020, 09:51 AM Thread Starter
MaintMech
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Front Axel Not Engaging

My sons Jeep. 2001 4.7 Limited with Quadra-Trac II On Demand 4WD System, and Vari-Lok Progressive Front Axle.


When in slippery conditions the front wheels don't engage at all. Transfer case is full with the correct fluid. You can see the driveshaft spinning but no power to the front.



Anyone got a clue as to where to start troubleshooting this?


Thanks!





'96 Grand Laredo, 4.0, Stock, Daily Driver

I fought Oracle and Oracle won!

Originally Posted by coralman
If the faith isn't there,the doubt is.
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post #2 of 11 Old 04-02-2020, 09:55 AM
LuthWJ77
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Search this forum for NV247 Transfer case and the common issues with it. See if it works in 4L but most likely the coupler that supposed to send power automatically in full time 4wd has failed.
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post #3 of 11 Old 04-02-2020, 12:06 PM
Double E
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Let me get this straight...QTII and Vari-Lok Progressive Front Axle...

That's an unusual setup.
Did you add Vari-lock to the front or was it purchased as a used vehicle that way?
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'04 Freedom Edition HO & '04 Overland HO (previous '00 Laredo 4.7)
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post #4 of 11 Old 04-02-2020, 04:41 PM
TheBoogieman
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Clutch pack is shot.
For the 1999-2004 Jeep Grand Cherokees using the NV247 transfer case, in "4-All Time" mode torque is applied to only the rear wheels under normal driving conditions. A gerotor pump is connected between the front and rear output shafts and senses any speed difference between them. When the shafts are turning at different speeds (wheel slippage), the pump supplies oil under pressure to a wet clutch pack. The clutch pack applies progressive 0 to 100% locking between the front and rear output shafts. For example, if the rear axle starts rotating at a significantly higher rate than the front axle, the gerotor pump causes the clutch pack to progressively lock, transferring torque to the front axle until both axles are driven at the same speed. The apply pressure in the clutch pack bleeds off slowly, which progressively unlocks the clutch pack and biases torque output towards "rear only" unless the rear wheels are still slipping. There is no center differential, so on dry pavement the front and rear output shafts cannot be locked without causing driveline binding. The "N" or neutral mode is intended for towing the vehicle. In "4-Lo" mode, the input shaft drives through a 2.72:1 reduction planetary gear set and the front and rear axles are locked together through the clutch pack.
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Quote:
Originally Posted by jeepinmichguy_ View Post
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03' Rubicon/Zone 4" coils with 1" spacers up front/Rancho shocks/5.13 gears-35" MTZs/Black Magic brakes.
99' XJ /4.0L-AW4/ 5.5" lift / Rancho RS5000X shocks/33" DC Extreme country MTs. Jeep #18
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post #5 of 11 Old 04-02-2020, 04:51 PM
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Quote:
Originally Posted by Double E View Post
Let me get this straight...QTII and Vari-Lok Progressive Front Axle...

That's an unusual setup.
Did you add Vari-lock to the front or was it purchased as a used vehicle that way?
Maybe he meant QuadraDrive and not Quadra-Trac II or he's misinformed.

p.s. He spelled axle, axel too.

Quote:
Originally Posted by jeepinmichguy_ View Post
TheBoogieman is a jerk.
03' Rubicon/Zone 4" coils with 1" spacers up front/Rancho shocks/5.13 gears-35" MTZs/Black Magic brakes.
99' XJ /4.0L-AW4/ 5.5" lift / Rancho RS5000X shocks/33" DC Extreme country MTs. Jeep #18
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post #6 of 11 Old 04-02-2020, 07:11 PM
Photoweborama
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Quote:
Originally Posted by TheBoogieman View Post
Clutch pack is shot.
yep, thatís what Iím thinking.

I test my AWD on a regular basis. I like to be sure so I donít get stuck. Locking into 4 low is ok, but for snow on road driving, I prefer AWD..

How do I test it? I find a hill where itís impossible to make without all four wheels driving. If I donít make it, the AWD isnít working. Hills with smooth river rock are the best to test AWD.


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post #7 of 11 Old 04-03-2020, 10:40 AM Thread Starter
MaintMech
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https://www.jeep.com/webselfservice/...GW58N01C664996



Here's the build sheet for this Jeep.


Clutch pack? Sounds expensive.


Axel, Axle, the shaft!

'96 Grand Laredo, 4.0, Stock, Daily Driver

I fought Oracle and Oracle won!

Originally Posted by coralman
If the faith isn't there,the doubt is.
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post #8 of 11 Old 04-03-2020, 03:28 PM
Double E
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So the build sheet indicates it is the QD with vari-locks front & rear.

Experts correct me if I'm wrong...
For troubleshooting, get both front wheels off the ground (jack stands). Put the shifter in neutral and spin one front wheel forward.
It should begin to spin the other wheel in the opposite direction, then get more difficult to turn, then immediately after the other wheel should spin the same direction. That will tell you if the differential is OK or not. Do the back wheels too just to get a reference on how it should operate.

For the transfer case internal check, on a slick surface, see if both fronts spin. If not, put the TC selector in low and see if the fronts grab. If so, I believe the progressive coupler is suspect.

'04 Freedom Edition HO & '04 Overland HO (previous '00 Laredo 4.7)
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post #9 of 11 Old 04-03-2020, 08:49 PM
Bigrigr
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How is the fluid in the front diff? Maybe its time to service the Vari-lok. The friction modifier seems to make all the difference, and is supposed to be changed every 20-30k miles. Maybe try swapping the fluid and see if it makes any difference before replacing the complete assembly...

'00LMTD-4.7l,242hd,D30,D44A,3.73's,True-trac front,Spartan rear,4" short arm lift,JK'sW/32's
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post #10 of 11 Old 04-04-2020, 09:39 AM Thread Starter
MaintMech
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O.K. Let's put this to bed. My mind is blown!!


Turns out that the drivers side axle was too short! When my son got this beast the CarFax said it had been is a front end accident. We didn't think much of it, everything looked pretty good.



I'm guessing that the axle was replaced with the incorrect one, it wasn't sitting in the differential, attached to nothing.



Everything works great now. Problem solved.


Thanks for the help!

'96 Grand Laredo, 4.0, Stock, Daily Driver

I fought Oracle and Oracle won!

Originally Posted by coralman
If the faith isn't there,the doubt is.
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post #11 of 11 Old 04-05-2020, 01:15 AM
Bigrigr
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Ah yes! The axles are different for the Vari-lok diffs! Thats impressive that you found it so easily!

'00LMTD-4.7l,242hd,D30,D44A,3.73's,True-trac front,Spartan rear,4" short arm lift,JK'sW/32's
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