Stick slip condition?

[Big J]

My Cherokee seems to have a stick slip condition when turning sharp corners slowly... like doing tight circular turns. It acts like a non-QT transfer case when you've got the front hubs locked and it in 4wd and the ground surface isn't that giving.

Is this a stick slip condition? Or... could this have something to do with the clutches in the t-case? Do these clutches ever wear out? If so, what happens when they do? <breath...> smile.gif

Or, is this normal?!

[joe]

Sounds like it's locked in E-Drive. No it's not normal. I'd stay off paved roads till you get the E-drive unlocked.

[ August 16, 2002, 12:23 AM: Message edited by: -joe ]

[joe]

How long have you owned this rig? How long has this condition been happening? Is it steering stiffly or normally?

My above post assumed you've had the Chero for awhile and this condition is new and it's likely you're in E-drive. Try to figure out if the pull-hesistate-pull-noise condition is from your front axle being engaged and the tires are chirping in tight corners or if the condition seems just in the x-case and not the front axle.
If the rig is new to you...slip stick condition in tight turning is when you don't have the right lube in the QT. I suppose fluid being really low could do it too or the QT is diluted with AT juice leaking into it from a bad seal. The only other possibility that causes slip stick is when you just changed the lube with 30w non-dtergent motor oil and used the LSD additive. Then you need to drive in fig eights for 10 minutes or so till the slip stick goes away while the fluid is getting mixed. If that's not the case you need to check the fluid for level and if it's the proper fluid and/or see if it's in e-drive. Then go from there. In any case it's not supposed to be doing that. If it's in e-drive you'll need to get it out or you'll at least blow a u-joint and possibly worse if you drive it on pavement. If it's the wrong juice you need to change it or you'll burn up the clutch cones($350 plus labor). If it's got AT juice mixed in then you'll need to fix the seal.

[Big J]

I am pretty sure it is coming from the transfer case. The slight stick-slip motion/noise seems to transfer through the front driveshaft, but doesn't come close to churping the front tires. It's not nearly as bad as a part-time t-case engaged on pavement. Steering isn't affected.

I haven't had the vehicle very long. It had been sitting for a long time before I got it. There is a small leak in between the transmission and transfer case which I hadn't really addressed since it was small. So it is possible it could be leaking into the transfer case?

Is it possible it would be stuck in e-drive even when the e-drive light goes off?

I'll check the oil level today, and maybe change it.

[ August 16, 2002, 10:41 AM: Message edited by: Big J ]

[mdill]

All full time 4x4's give some feedback when turning sharply on a dry surface,
if you have hubs most likely the QT has been converted to be a part time case
so you really sould not get any feed back IF a: you are truly in 2wd mode
b: the PO did not add some sort of locking diff to the front.
If b: you will always have some feed back when the hubs are locked, if you
are in 4X mode and it is truly a converted case, don't drive on pavment untill
you figure how to get it in 2X mode.

Mike D.

[Big J]

I've got a plain old full-time Quadra-trac.

[nightflyers]

First, if it is just a plain full-time QT, make sure the hubs are never unlocked unless the e-drive is engaged.

I found with mine that the PO used gear oil in the QT. The damage was already done. The cone to the front yoke was shot. They really are not that hard to fix it is just the parts are no longer made. I found in every QT I opened the front one was shot and the rear one was perfect.

[nightflyers]

Oh ya. forgot. You can test the cones for wear without opening the QT. Just take the front driveshaft off and put t tourqe wrench on the yoke. The yoke should not be able to be turned with any less than 80Lbs of force. If it can, than the cones are shot.

[joe]

Originally posted by nightflyers:
Oh ya. forgot. You can test the cones for wear without opening the QT. Just take the front driveshaft off and put t tourqe wrench on the yoke. The yoke should not be able to be turned with any less than 80Lbs of force. If it can, than the cones are shot.I'll add a little to the above about the torque bias test.
Tranny in neutral, QT "not" in E-drive, remove "rear" drive shaft. Get somebody to stand on the brakes just in case. Add the socket and torque wrench to the yoke nut and as Scott said the cones shouldn't turn before appliying 80 ft-lbs. If it's still not turning by the time you get to 170 ft-lbs odds are it has the wrong lube in it(no LSD friction modifier).

[Crazy_Jeepman]

Slip stick condition is when the clutch cones are getting dry. It will chirp the front or rear tires on hard surface, but not all the time. What is happening is the clutches are not releasing when they should, so it forces the tires to release wind up, or the clutch will release with a bang, or a loud clunk. But with Q-trac it is possible to have the front wheels powering you and this would make it feel like you are in 4 wheel drive as well. If you feel it is stick-slip check fluid, then go to a parking lot and in reverse do tight sepentine paterns for several 100 yards and see if that helps. This forces the oil up into the clutch cones. If you have ATF in the T-case you will need to take care of that right away.

[Big J]

Thanks for all the info everyone. I ended up changing the t-case oil. I used the specified 30W Non-detergent oil, and GM limited slip concentrate additive.

It did make a noticeable difference. Turning sharp turns isn't totally smooth, but it is much better, and doesn't make the clunking noise it did before.

I'm not sure if the procedures are different depending on the year of vehicle, or if they changed the procedure for the Torque Bias Check over time, but this is what my '74 Jeep Service Manual says:

<begin quote>

Torque Bias Check
(1) Be sure Quadra-Trac lockout is not engaged. The differential must be free to operate and not locked.
(2) Place transmission in P (Park).
(3) Lift and support vehicle in a manner which will allow front wheels to turn freely.
(4) Disconnect rear propeller shaft front universal joint from transfer case rear yoke.
(5) Use a socket and torque wrench to apply torque in tightening direction (clockwise) to transfer case rear yoke retaining nut. Differential cone clutches should slip when 110 to 270 foot-pounds of torque is applied.

NOTE: (in italics) Slippage with torques below 110 foot-pounds indicates the need for differential unit replacement. If the unit will not slip by applying 270 foot-pounds torque or less, improper lubricant may be the cause. Refer to Stick-Slip Condition and to Lubrication Change - With Reduction Unit in this Section. If addition of concentrate or changing lubricant does not correct the condition after reasonable mileage, the differential unit should be replaced.

<end quote>

[joe]

Originally posted by Big J:
I'm not sure if the procedures are different depending on the year of vehicle, or if they changed the procedure for the Torque Bias Check over time, but this is what my '74 Jeep Service Manual says: Nah...same x-case and you can do the test either way. It's just that by 76(?) they figured out you really don't have to get the rig off the ground to do it...hence the later proceedure and later torque specs. Glad ya got the prob solved and it was a "cheap-n-easy" solution. ;)