I lifted my 94 ZJ 3.75 inches with a front to rear coil swap using my 3 inch skyjacker lift coils off my old 84 XJ. I did not use front track bar relocation bracket from the XJ because I had bad problems with it on my XJ. I instead filled the original trackbar hole on the axle side with weld and redrilled the hole where it needed it to be to compensate for the lift. The problem now is that it gets death wobble what feels to be in the rear end. It specifically feels like in is in the right rear. Most people who have had this claim they feel it in the front and the steering wheel shimmys. my steering is unaffected and I have no problem controlling the ZJ. I have to slow down to about 30mph till it corrects itself. I am curious if anybody else had similar problems with the rear end with death wobble and if there is a way to adjust castor angle's in the rear which from looking at varoius jeep forums is usually the cause of death wobble. Any help would be greatly appreciated.
94ZJ rear end death wobble
- Thread starter ROGLSTUBB
- Start date
Bounty__Hunter
Super Moderator
It may be a vibe, but never heard of a rear vibration referred to as death wobble. Does the vibration change during acceleration/deceleration?
Be sure to adjust the rear track bar so the axle is centered.
Install longer lower control arms to correct suspension geometry.
Install cam bolts in the control arms to adjust pinion angle parallel with the transfer case output shaft.
Lower the transmission crossmember .5" if needed to correct driveline vibes.
Rotate the tires and see if the vibration moves.
Be sure to adjust the rear track bar so the axle is centered.
Install longer lower control arms to correct suspension geometry.
Install cam bolts in the control arms to adjust pinion angle parallel with the transfer case output shaft.
Lower the transmission crossmember .5" if needed to correct driveline vibes.
Rotate the tires and see if the vibration moves.
Thanks for the quick response. I too suspected tires to out of balance and had them balanced and although they were out of balance it still did its wobble for me once more. I was thinking of dropping to Tcase too to correct angle and had brouught home some 3/8 spacers from my work to try before I read your post. I glad I am thinking in the right direction. I took the jeep to a railroad crossing that I know will cause the wobble and after a few tries got it do its thing and strained my neck out the window and saw both front and rear shaking so this might still be that death wobble I keep hearing about. As far as accelleration and decelleration I am not sure it seems to it only some times but more at no load at all.
I have not lengthed rear track bar as of yet. I was debating whether or not to cut it and weld in a piece of sch40 pipe or construct a lower point on the frame to reattach stock length track bar. I was told the track bar works better the closer it is to parellel as long as it does not actually go below axle mounting point
I did correct toe-in and steering wheel center after moving front track bar. But I did not adjust castor angle does anybody have this angle or do I just match front output shaft on Tcase?
I have not lengthed rear track bar as of yet. I was debating whether or not to cut it and weld in a piece of sch40 pipe or construct a lower point on the frame to reattach stock length track bar. I was told the track bar works better the closer it is to parellel as long as it does not actually go below axle mounting point
I did correct toe-in and steering wheel center after moving front track bar. But I did not adjust castor angle does anybody have this angle or do I just match front output shaft on Tcase?
Bounty__Hunter
Super Moderator
Caster should be between -5* and -8* I believe, double check with an alignment shop for factory specs. Sleeving the rear track bar would be fine for extending it, that's how I did my front.
Well I finally figured it out. I tried lengthening the rear sway bar, changed the rear coil spring Isolators to XJ front coil spring Isolators, loosened all control arm bushings and tighted them with the wheels on the ground, Borrowed a laser surveying tool from my work and did my alignment myself and still did it. My brother suggested that I tried using the lower control arms from my old XJ that had come with the skyjacker lift. To my surprise it solved the problem. I am not really sure if the stiffness of the control arms themselves "stock ones will twist easier" or that one of the old control arm bushings on the axle side of one looked like the rubber was cracked and peeling away from the metal inner piece. Anyway no more wobble "at least for now. Thanks for all you ideas.
Bounty__Hunter
Super Moderator
Good it's fixed. Did you replace stock control arms with longer aftermarket arms?
The skyjacker control arms are a about 1/8" longer than stock but I dont think the length mattered. The cam bolts gave me that and more on the stock control arms. I think the fact the bushing was about broke on the one control arm was my problem. Maybe that the skyjacker control arms are a little more rigid helped too. I should have just replaced the stock control arms with the skyjacker arms in the first place. After all they did come with the lift for the XJ and there is probably a reason for that. And its not like the red color on them didn't match my red ZJ. I dont know what I was thinking.
Bounty__Hunter
Super Moderator
I've heard of longer lower control arms fixing death wobble many times. That's why I recommended above:
Bounty__Hunter said:
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