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Old 08-27-2011, 10:04 AM   #1
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Posi-Trac Problems...help

I have posi-trac in both the front end and rear. I think I am having some problems with the posi-trac or it may just be normal for some things to happen. When i am driving there is a lot of vibration and sometimes even the death wobble. It can be so bad sometimes that it feels like my tires are going to fall off. Also when I am on concrete in 4Lo and try to make a sharp turn my tires wobble like they are going to fall off, I don't even know how to describe how badly they wobble when making a sharp turn. It can be to the point I'm scared my tires are going to break off from my axles or something. Is this because of the posi-trac or what? I also have 3'' lift and 35''s

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Old 08-27-2011, 10:14 AM   #2
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Don't drive on hard surfaces in 4lo. Especially don't make sharp turns on hard surfaces. Your tires are all rotating at the same speed but the outside tires are going a greater distance. Does not work out to well.

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Old 08-27-2011, 10:17 AM   #3
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Also, I don't think your Posi has anything to do with vibration. I would check the u-joints. Again, u-joints won't cause death wobble, and there is a sticky on possible causes.
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Old 08-27-2011, 10:17 AM   #4
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First, did you install the Posi-Tracs front and rear? The factory never installed anything in the front axle except for a locker in the Rubicon.

Regarding what it is doing in 4Lo when you drive on concrete, that is normal when you drive on concrete in 4Hi or 4Lo. In fact, you should not shift into either 4x4 mode when on pavement or concrete. The Wrangler's particular type of 4x4 system is considered a "part-time" system which means it is only suitable for poor-traction offroad surfaces.

The reason it is bucking and wobbling when making turns in 4Lo on concrete in 4Lo is because when you're in 4x4, the axles are mechanically locked together. That means the front and rear tires are forced to turn at the same rate which means they will have problems during a turn. During a turn, the front tires need to turn faster than the rear tires so if they are prevented from doing so which happens in 4Hi or 4Lo, you'll feel problems. Only use 4x4 on loose traction surfaces or roads that are totally (!) coated with snow or ice. You can't even use 4x4 on wet roads since they have too much traction too.

Only with "full-time" 4x4 systems like you can get on a Liberty, Cherokee, or Grand Cherokee can you use 4x4 on pavement or concrete.

So far the Death Wobble goes, just how bad is it? Describe the DW symptoms.
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Old 08-27-2011, 10:17 AM   #5
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what about the bad vibration while driving eventually leading to the death wobble? its that caused by the normal stuff causing the death wobble or is it because of the posi-trac spinning the driveshaft continuesly while driving?
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Old 08-27-2011, 10:19 AM   #6
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The front driveshaft spins continuously no matter what (open, locker, or limited slip differential) you have in the front axle. The front driveshaft spins continuously on even stock Wranglers when in 2wd since it is being driven by the front axle's gears.
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Old 08-27-2011, 10:21 AM   #7
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Tires out of balance/alignment will cause a vibration that leads to wobble sometimes.
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Old 08-27-2011, 10:23 AM   #8
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The front driveshaft spins continuously no matter what you have in the front axle. The front driveshaft spins continuously on even stock Wranglers when in 2wd since it is being driven by the front axle's gears.
+1 it spins freely until you lock in the transfer case. Its not like locking hubs. With locking hubs, you can unlock the axles so they don't spin the gears or the drive shaft.
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Old 08-27-2011, 10:23 AM   #9
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ok, so it is normal for the tires wobbling while turning on concrete. as for when driving its normally always vibrates pretty bad, bad enough for my cellphone on my dash to bounce until it falls off and for the rearveiw mirror vibrating so bad sometimes i cant even make out what kind of vehicle is behind me. then a few times it will start wobbling as if the tires themselves were falling off or something. i recently had my trackbar replaced and tires realigned so i dont think its the normal DW symptons but i really have no clue.
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Old 08-27-2011, 10:34 AM   #10
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also a problem that i dont know how it was caused. right now my front driveshaft is not attached. a little while back i was having a lot of grinding noise in the front end. eventually after a little while of driving with the noise my jeep started vibrating stupidly. then a loud bang and the vibrating stopped. my driveshaft broke the bolts on the yoke on the differential. so now my drive shaft is no longer attached to the front diff but i still have the vibrating. i dont know whats going on haha.
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Old 08-27-2011, 10:35 AM   #11
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Did it start after the new track bar? Have you checked all the bushings to include the upper shocks?
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Old 08-27-2011, 10:36 AM   #12
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Quote:
Originally Posted by USmarine212
ok, so it is normal for the tires wobbling while turning on concrete. as for when driving its normally always vibrates pretty bad, bad enough for my cellphone on my dash to bounce until it falls off and for the rearveiw mirror vibrating so bad sometimes i cant even make out what kind of vehicle is behind me. then a few times it will start wobbling as if the tires themselves were falling off or something. i recently had my trackbar replaced and tires realigned so i dont think its the normal DW symptons but i really have no clue.
Have you checked your rear pinion angle? Might need a SYE and new driveshaft or a trasder case drop if there is too much of an angle.
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Old 08-27-2011, 10:39 AM   #13
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also a problem that i dont know how it was caused. right now my front driveshaft is not attached. a little while back i was having a lot of grinding noise in the front end. eventually after a little while of driving with the noise my jeep started vibrating stupidly. then a loud bang and the vibrating stopped. my driveshaft broke the bolts on the yoke on the differential. so now my drive shaft is no longer attached to the front diff but i still have the vibrating. i dont know whats going on haha.
I would guess you broke something in the front end, maybe teeth, while you were driving in 4lo on the concrete. You should get that fixed and go from there on the vibrations if it continues after you fix it.
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Old 08-27-2011, 10:41 AM   #14
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Pull the front cover off and check it out. Get ready to catch some springs if it let go.
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Old 08-27-2011, 10:42 AM   #15
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Heck that could be his whole problem^
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Old 08-27-2011, 10:42 AM   #16
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Have you checked your rear pinion angle? Might need a SYE and new driveshaft or a trasder case drop if there is too much of an angle.
the rear pinion angle is fine, there is no vibration in the back. its all coming from the front. i'm wanting to get a sye for the front but have no clue about any of that and dont know what all has to go with installing a sye.
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Old 08-27-2011, 10:45 AM   #17
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Originally Posted by USmarine212

the rear pinion angle is fine, there is no vibration in the back. its all coming from the front. i'm wanting to get a sye for the front but have no clue about any of that and dont know what all has to go with installing a sye.
Then I'd do like the others say and crack open the front diff and hope you don't see chunks!
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Old 08-27-2011, 10:47 AM   #18
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I would guess you broke something in the front end, maybe teeth, while you were driving in 4lo on the concrete. You should get that fixed and go from there on the vibrations if it continues after you fix it.
i pulled the cover off the diff after the driveshaft broke from the yoke. there were no metal pieces in the oil, and all the teeth on the gearing was fine. i didnt see any damage inside. the only thing wrong with the diff right now is the yoke has about 1/8" play up and down. but even with the drive shaft not connected in the front there is still vibration and the dw
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Old 08-27-2011, 10:49 AM   #19
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The pinion shaft that the yoke is bolted to can be moved up and down 1/8"? Sounds to me like the pinion shaft/bearing is shot and needs replacing.
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Old 08-27-2011, 11:10 AM   #20
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Did it start after the new track bar? Have you checked all the bushings to include the upper shocks?
what should i check on the upper shocks? and it was happening before and is still happening now. i havent driven it in 3 months because im on deployment in the middle east but my younger brother is driving it now so everything i have to figure out now is coming from him.
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Old 08-27-2011, 11:11 AM   #21
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Bearing at the least. If it is moving that much it is definately causing a vibration while it is spinning.
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Old 08-27-2011, 11:12 AM   #22
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The pinion shaft that the yoke is bolted to can be moved up and down 1/8"? Sounds to me like the pinion shaft/bearing is shot and needs replacing.
yea, im changing the bearings for the pinion shaft and everything including a new pinion oil seal. but that would be whats causing the vibrations is it?
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Old 08-27-2011, 11:15 AM   #23
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what should i check on the upper shocks? and it was happening before and is still happening now. i havent driven it in 3 months because im on deployment in the middle east but my younger brother is driving it now so everything i have to figure out now is coming from him.
If the upper shock or lower shock bushings are bad or the mount has come loose it could cause the vibration/wobble. Any bushing in the front end will do that. Even the rear track bar being loose will cause violent wobble. Have him shake all the shocks and have someone turn the steering back and forth while he looks to se if anything looks loose or worn.
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Old 08-27-2011, 11:17 AM   #24
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yea, im changing the bearings for the pinion shaft and everything including a new pinion oil seal. but that would be whats causing the vibrations is it?
It is spinning while the vehicle is moving? With gears meshing together on one end and the other end flopping around it will vibrate.
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Old 08-27-2011, 11:23 AM   #25
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It is spinning while the vehicle is moving? With gears meshing together on one end and the other end flopping around it will vibrate.
i'm a little confused on what you mean by that. the yoke still turns then the jeep is driving. the front driveshaft is idle while driving though. the only bad bearings inside the differential is the bearing for the pinion.. atleast as far as i know.

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