ghack

I have a 2000 Grand Cherokee with the Quadradrive. We bought it last summer, and now winter is here, I find all wheel drive isn't working. I jacked up all 4 wheels, and ran it in idle. Both rear wheels turned. The passenger side front was also turniing, I squeezed a pipe under it to stop it, it made a few clicking noises in the front differntial, but the driver's side still didn't turn. I also noticed that the front drive shaft was still spinning with both front wheels stopped. Doesn't seem like a good thing to me. Any specific ideas about what could be wrong with the differential and/or rough estimates to fix. I'm thinking of taking it to a Jeep dealership to get an estimate.

dnuccio

nothing is wrong. the quadradrive system uses the NV247 transfer case, which sends 100% power to the rear wheels under normal driving conditions. if it senses the rear tires slipping, it will direct some power to the front axle. this system is explained in more detail here:
http://en.wikipedia.org/wiki/Quadra-Drive#Quadra-Drive

ghack

I got stuck in the snow on a small hill. The rear wheels were spinning, but no help from the front. The AAA driver who had to pull me out was surprised it was stuck. Maybe it's not detecting the rear wheels spinning. Could it be just low fluid that would cause that? I only checked the back differential so far, and that was fine. Also, with the front driveshaft turning, shouldn't the front wheels be turning too?

dnuccio

sounds like a problem with the limited slip in the front axle, i dont know enough about the system to be able to diagnose it any further, sorry. good luck

ghack

I'm going to check fluid. If that's ok, I may tear into the front differential to see what's up.

mr.clean

Did you try it in 4 low? I am not for sure how this whole system works, but if the front drive shaft is turning, it should be sending power to the front end. If you have the whole Jeep jacked up and you stop that tire, the computer should think that the other tires are spinning and send power to that tire while taking power away from the others.

dnuccio

its not controlled by computers.

dave1123

The clicking in the front diff has me stumped. Seems to me if you stop the wheel that's spinning, the other should spin. That's the way an ordinary diff works. Is there a vacuum line or pressure line going to it? I believe with a front locker, there is an air pressure line going to it.

dnuccio

its not a locker, its limited slip. its hydraulic all self contained

ghack

I added fluid, but no joy. Passenger front turns ok, but stopping it doesn't get the other turning while front drive shaft continues to turn. I pulled cover off, nothing obvious bad, no metal filings. Don't know how to test with no fluid so i can watch gears. I believe it's a hydraulic pump that pressurizes when axle speeds are different. Not sure how it puts pressure to one side or the other.

mr.clean

talked to my Jeep mech. today about how quadradrive works and your what you said your Jeep was doing. He said that it could only be two things that could cause your problem. You had a broken axle or the pump in the frontend system that locks the front end up was bad. He said the only time that he has seen one that quite like yours, they had a broken axle.

ghack

Thanks for the thoughts and ideas. Sadly, i think it is a bad internal pump/clutch. The inside gear on the driver's side turns with the wheel like it should. The pump is supposed to squeeze the clutch plates and lock the two axles. I saw one price for varilock for $750, ouch. I don't think there are rebuild kits. Maybe i could find a used one. It does seem a little strange that it's just the passenger side that normally turns. Maybe that's the design.

ghack

I'm guessing lack of the friction modifier wouldn't cause the problem. I had to add some fluid, maybe 2/3 of a qt I got from the jeep dealer. I didn't add any modifier though. It seems that it would develop some pressure with just fluid, maybe not enough to pull me out of a snowbank, but probably enough to spin the wheel when off the ground. Just thinking out loud.
Anyone know how hard it is to replace the vari locks and what's involved with it? I'm guessing I would have to pull each axle out, but not sure. The assembly looks like it's bolted into the pumpkin on each side, bearing clamps maybe?

ghack

I found a used hydra lok for 220. I would just have to swap bearings and ring gear. Another option is I found a complete front end with 90 day warranty for 350. I was also looking at the Aussie lockers for 250. Any idea how hard it is to swap bearings and ring gear out. I have a press. Also, how hard/how much time is it to change the whole front end. For the third option, it seems like some people like the Aussie. Any opinions here on that. I guess it would serve the same function as the hydralok/varilok. It just works differently. It's independent of the transfer case and rear end and self activated.

ghack

I ended up getting the whole front end. A mechanic friend thought it would be easier to change the whole front end vs swappig gears. Halfway thru the change and after a late night, and dealing with a few damage issues when they pulled the replacement at the junkyard, I'm not sure I agree. Anyway, I got the old one out, but i'm having trouble getting the coil springs onto the bottom insulator. Someone said they just twist on, but it doesn't go on easy, and it starts to distort the rubber since the end of the spring isn't a true coil, it's made to sit flat, so the end is close to the next coil. Any suggestions or tips for getting the springs to thread on? I was hoping I could align them and they might just pop into place under pressure, but now I'm not so sure.