I have joined the vibration club

reservoir dog

reservoir dog

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Nov 10, 2020
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Georgia
Hello , I too have joined the vibration club. I lifted my 2004 tj 2.5 inches and replaced the shocks with rancho 5000x per all the recommendations here. Also new 33s and wheels. The jeep rides and drives better than stock. After the lift I had the typical vibes at low rpm acceleration , dropped the T-case/ skid , cured those vibes. I never drove it over 45mph until after I did the t-case drop. Now I take it out , get up to 50mph and above and get vibrations. I removed the front drive shaft and the vibes go away . I sent my front drive shaft to a shop that does all our fleet drive shafts here at work and they say its fine . Now for my question, if the drive shaft is fine should I go to adjustable C/As in the front and fine tune the angles , upper or lower? This is street queen only .
 
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Were the bushings in the control arms good? Did you re-align the front after the lift? Even a small lift will change the front steering geometry.
Make sure your steering wheel is perfectly centered first. Do a steering 'dry test's to be certain all steering parts are tight. Without this you will never get the front end to act right. Then set your toe-in to 1/16 to 1/8".
Test drive. Is it better?
Check that all your tire pressure is in the 26-29 psi range, and all are the same.
Test drive. Is it better?
Rotate the tires front to back. Have them all re-ballanced if necessary. Explain to the tech that the TJ is extremely touchy about balance and to be as exact as possible.
Road test. Is it better?
From here we start to get into more touchy opinions of where to go next, but you should have the vibes taken care of by now.
 
I did have the tires remounted ,rebalanced and rotated before I removed the front drive shaft , it made no difference. The steering wheel is straight which surprised me, I was fully expecting to have to adjust it after the lift. I've gone up and down with tire pressures from 35 to 26 psi, I have a very accurate dial type gauge, I did all of this before I removed the front shaft. Everything was fine before the lift .
 
CharlesHS said:
Since you removed the front DS and the vibrations went away and had the DS checked professionally; then I would suggest you check the front DS angles. You may have added too much tcase drop or possibly not enough. You wont know until you do the measurements.
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Here's your winner right here... You did the right thing pulling in the front shaft.... That's where a lot of shops start.

The front is a double cardan... So ideally you want the shaft in line with the pinion at the very front... The double cardon will take care of the remaining angles.

I went through all this a while back... I can't remember all the details... But as much as you can determine the front drive shafts relationship to the differential and a lot of differentials have a flat space on the vertical that you can check your angle... It will be 90° different than the horizontal but you can sort it out from there.

Again if I'm mistaken...don't take my word for it but you want the differential in a straight line into the shaft up front... At the same time you're trying to get appropriate caster...if you dial in a little more caster in the process it's probably not going to hurt anything but if you get too little you're steering will get light and floaty.
 
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I know you said that a shop checked your driveshaft already but a 2.5 lift should not be causing front pinion angle related vibrations. I had bad vibrations coming from a driveshaft and I wiggled all the u-joints and they felt fine. After unsuccessfully trying some other things I replaced all the driveshaft u-joints and it totally solved the vibrations. Those u-joints can be deceptive and lots of people on this forum have solved vibration issues by replacing them.
 
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I'm with you HornedToad, I didnt think 2.5 should cause any problems with the front , maybe the rear , but here I am. I probably won't even reinstall the front D/S until after the holidays , too much going on. I also need to spot weld the frame inserts for the skid so I can experiment with the Tcase drop more easily, got a couple trying to spin on me. Next I think I will remove the Tcase drop , reinstall front D/S , remove rear D/S and see what happens. If no vibes then I know for sure it's a front angle problem.
 
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HornedToad said:
I know you said that a shop checked your driveshaft already but a 2.5 lift should not be causing front pinion angle related vibrations. I had bad vibrations coming from a driveshaft and I wiggled all the u-joints and they felt fine. After unsuccessfully trying some other things I replaced all the driveshaft u-joints and it totally solved the vibrations. Those u-joints can be deceptive and lots of people on this forum have solved vibration issues by replacing them.
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Good post.

We had one guy that had a slight Bend in one.

A double cardan rebuild is a good thing if needed.
 
I agree 100%, even though they did check the D/S , they spin them on a straight axis , no angle. A u joint rebuild while it is out would be a good idea.
 
Good morning, I hope everyone had a safe and merry Christmas! I am reviving my old thread to update on my vibration issue after my lift install in case it my help someone else. I installed an Adams front driveshaft over the holidays and all vibrations are gone. I possibly could have put new U joints in my stock D/S but my thinking was,$60 bucks for 3 spicer u joints and a couple of hours work that may or may not cure the vibes or a new D/S that could be returned if it didn't cure them. To recap, 2.5 lift, 1.5 transfer case drop cured rear vibes, new front D/S cured front vibes. Ran it up to 80mph and smooth as silk, thanks for all the replys !!
 
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I'm a novice when it comes to lifts and drops and such, I have a 98 with a 2.5 inch lift and everything else is stock and never had any vibrations or such. Is it normal to have to modify all you did for a 2.5 inch lift?
 
I would think not with only 2.5 lift, however I did not take any measurements prior to the lift install so I may have netted more than 2.5 inches. Also I was working alone and did not remove the front D/S as I should have , I was applying a lot of down force on the driver side to get the spring in and may have warped the D/S. Not sure, but its cured now .
 
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