Lift Done....Drifeshaft Vibrates

90growler

New member
Lift Done-Rear Vibrates

Whew...Finally completed the 2" BB for the XJ. I think it turned out great, but I have one small problem. The rear vibrates from 27-30 MPH then goes away. I have taken it up to 75 with no problem until it goes back to 30. Any solutions?

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check your u-joints, and if they are good; put those aluminum alignment shims inbetween the rear axle and leafs. that would be my guess if the U-joint binds, but on my XJ i put a 4'' buget boost and in 2wd i could pound it pretty well with no more vibrations that it had before.
 
Don't use aluminum shims... use steel ones. The aluminum ones are prone to cracking/breaking.

You can try a set of shims, but you may find that a small transfer case drop may be needed. Most kits are 1", but for a 2" BB you could probably get away with a 1/2-3/4" drop that you can make yourself. Bounty Hunter had to do that on one... he can probably tell you what worked for him ;)
 

Doesn't it seem wierd that it only does it at one speed? I called Rocky Road and they said I should have no problems with 2" BB and I don't need TC drop. They said I may have bad U-joints, but I replaced those with longer ones. Could I need to just tighten them down again?
 
Doesn't it seem wierd that it only does it at one speed? I called Rocky Road and they said I should have no problems with 2" BB and I don't need TC drop. They said I may have bad U-joints, but I replaced those with longer ones. Could I need to just tighten them down again?

It is very common for the later XJ's (97 - 01), even on a 2" BB, to have driveline vibes that require a TC drop. Do a search on NAXJA and you will see that to be true.

Rocky Road is wrong, and considering they think 4.5" of lift should have stock control arms, nothing they say surprises me. They make solid hardware but I question their intentions.

I think you misunderstood U joints for U bolts???

Your U joints (joints in the driveshaft ;) ) are easy to check, but if they were fine at stock height I doubt they are an issue now. I would not waste time or money on them if they have no play in them. If they do show wear then you need to replace them before they give.
 
It is very common for the later XJ's (97 - 01), even on a 2" BB, to have driveline vibes that require a TC drop.

Very true, many even had vibes from the factory and the stealership fix was a transfer case drop (on a stock jeep). Good friend of mine had vibes but he had the 1" UpCountry factory lift option.

Are you sure it's the rear? Be sure to adjust your caster in the front axle all the way out, this will improve driving and prevent any vibes from poor pinion angle of the front axle.
 

Most kits are 1", but for a 2" BB you could probably get away with a 1/2-3/4" drop that you can make yourself. Bounty Hunter had to do that on one... he can probably tell you what worked for him ;)

Scale of difficulty 1-10
 
I made a 1/2" TC drop for our '98 XJ that was lifted 3". Just took a piece of 2" wide 1/4" thick bar stock and cut it into two lengths about 6". Then set the transmission crossmember down on each section of bar stock to mark the holes for drilling. Use a pipe wrench to back out the stud on each psuedo-framerail, and install with 4 bolts 1/2" longer than stock. Piece of cake.
 

I made a 1/2" TC drop for our '98 XJ that was lifted 3". Just took a piece of 2" wide 1/4" thick bar stock and cut it into two lengths about 6". Then set the transmission crossmember down on each section of bar stock to mark the holes for drilling. Use a pipe wrench to back out the stud on each psuedo-framerail, and install with 4 bolts 1/2" longer than stock. Piece of cake.

the studs on mine were a pain. Thank goodness for the blue wrench!
 

Rusty's has a $20 kit. Is it really as simple as dropping the bolts and putting in the spacers? What about the TC shifter?

I used a Skyjacker kit on my '00 XJ. It was pretty easy because with that kit you don't need to remove the one threaded stud (you'll see when you do yours). The Skyjacker kit is more than you need though - it is a 1.5" drop (I had 4.5" of lift on mine).

You won't need to do anything with the shifter or linkage. The one stud I referred to has to be removed. I hear it can be a PITA but never had to myself.
 
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