2006 Cherokee KJ vibration after lift

kj75 · **Posted:** Mon May 09, 2016 9:56 pm

Hi all,

Recently installed a 50mm lift kit and now I get some vibration at around 1800rpm at 70km/h and again at about 100km/h, but only on very heavy acceleration.
This did not occur before the lift, so I am trying to rule out Auto TC issues.

My current lift (measured from bottom rim to wheel arch) is 735mm in the front and 750mm in the rear. Before the lift it was 690mm in the front and 695mm at the rear.
So previously there was 5mm difference between front and rear while now there is 15mm difference.

Could this larger difference between front and rear give me vibration issues as the driveline angles would have been changed ?
Should I do a clevis lift in the front to get it a little higher to match the rear (to about 745mm) ?

I recently did some research on how to set the correct driveshaft angles using a protractor, and I will try and work out the exact shim size for the transmission drop.

Should I look into a drive shaft spacer as the slipyoke is sligthly pulled out further now that I have a lift. However I am not aware anyone selling the spacer for our Jeep. Would the spacer help solve the vibration issue as it would push it in more and make better contact ( or get longer shaft but more money) ?

Existing Ujoint do not have any slack in them so I am not sure if I should replace them with the new Moog 280 I recently purchased.

I will also have to grease the yoke as I can sometimes feel a clunk in the driveshaft when changing into second gear.
At 10 Years of age I don't think it has ever been greased.

Any pointers would be welcome.

KJ75

RenKJ · **Joined:** Sat Jan 24, 2015 4:45 am **Posts:** 96

Did you get alignment done after the lift?

kj75 · **Posted:** Tue May 10, 2016 4:50 am

Alignment was done twice in fact and also have brand new tyres.
Shudder / vibration only occurs on heavy acceleration, and not when accelerating gently.

lfhoward · **Posted:** Tue May 10, 2016 1:28 pm

Driveline angles shouldn't be an issue for a 4 inch (100 mm) lift on an 06 KJ Liberty/Cherokee, let alone a 2 in (45-50 mm) lift. Many have lifted to that height with no issues. With the independent front suspension, the front drive shaft does not change at all, so you can rule that out. The angle of the rear drive shaft is not changed enough to need any kind of SYE like you might have needed on an XJ Cherokee back in the day.

Here's what I would check if the vibration is coming from the front:
- Check the rubber boot on the rear of the front driveshaft before it goes into the transfer case. This boot often disintegrates leading to the joint needing replacing. This happens even in unlifted KJ's.
- Check your front CV's. Are the boots intact and the CV's ok? The angle of the CV's shouldn't be a problem, but if one of them was already on the way out, it might be making more noise/vibration now.
- The intermediate shaft between the front diff and right CV is sometimes the cause of vibration, but I would check those other things first.

If the vibration is coming from the rear:
- Check the U-joints on the rear driveshaft to make sure they are ok.
- Check the ball joint on your rear upper control arm (the boomerang) to make sure it is alright. If there is play, it might vibrate when the force of heavy acceleration is applied.

Otherwise:
- Do you have an unbalanced wheel? Any wheel weights missing?

kj75 · **Posted:** Tue May 10, 2016 3:57 pm

I have the Jeep in 2wd, so I think the vibration is coming from the rear.
Have to put it in 4wd and remove the rear drive shaft to verify.

To check front CV I turned the wheel all the way and slowly went in circles and didn't hear any clicking.

Tires have been balanced plus it's not speed related but acceleration. Accelerating gently is fine and no vibration whatsoever.
All the boots are intact an I could not feel any play in the ujoints (waiting for Moog 280 greasable ujoint to arrive).
If the boomerang ball joint is worn, why would the vibration only occur after the lift and not before (perhaps extra stress) ?

I did feel a tiny movement or slop in the back. For example coming to a stop, there is a delayed movement in the rear.
I think this may be worn rear lower control arms. From what I hear the bushings in these have voids in the rubber making them weak and prone to failure.

I have new front UCA, lower ball joint as well as new clevis bushes installed already.

RenKJ · **Joined:** Sat Jan 24, 2015 4:45 am **Posts:** 96

This is a weird question but all i can think of given what you tried already would be to check if the harmonic dampener is still attached to the front of the rear diff?

kj75 · **Posted:** Wed May 11, 2016 5:14 pm

The dampner is still there from what I can see.

I was speaking to Yeti about this and he advised he also had issues after a lift, and he had to drop the transmission 1.5cm.
The other issue could be that the inner CV joints are worn as well.

I will rip out the rear shaft on the weekend and go for a drive in 4wd.
If the vibration is still there it means it's the front that's the issue or it is in fact the dreaded TC.

I was talking to Yeti about this and he said even with a small lift like mine I should be dropping the transmission a small amount. I also read on a Prado forum that they had to drop the transmission which helped get rid of inner CV vibrations.

KJ75

kj75 · **Posted:** Sun May 15, 2016 2:56 am

Lowered the transmission 1cm and when there are 2 adults in the back the shudder / vibration is gone.
This is to me seems to be driviline angle related in the rear.

tommudd · **Posted:** Mon May 16, 2016 1:27 am

NEVER had to lower any transmission mount on any we did here
If sit up right don't have to
Ran over 4inches of lift on my 04, had the vibration dampener removed a swell
try looking at u-joints etc that maybe bad

kj75 · **Posted:** Tue May 17, 2016 8:05 am

Yes agreed the ujoints could be going, and will be looking at replacing it.
However if Ujoints are going then why does putting weight in the back reduce vibration ?

tommudd · **Posted:** Tue May 17, 2016 12:34 pm

kj75 wrote:

Yes agreed the ujoints could be going, and will be looking at replacing it.
However if Ujoints are going then why does putting weight in the back reduce vibration ?

Changing the angle back to more where it was before the lift
When I lifted one KJ it was the same, owner wanted small 2-2.5 inch lift, KJ had over 100,000 miles on it at the time.
Small vibration , load it up vibes went away
Pulled the u-joints and they were almost rusted solid , no grease at all
So changed the angle when we lifted and as soon as I replaced the u-joints vibrations went away

kj75 · **Posted:** Sat May 28, 2016 7:16 am

Good to hear someone else had the same experience as me, and that it was fixed by replacing the ujoint.
I have about 140000Km on the Jeep, so most likely the Ujoint is worn, and will replace it in the coming week.

kj75 · **Posted:** Fri Jun 03, 2016 11:09 pm

Today I removed the rear shaft and inspected the Ujoints. Everything seemed nice (no slop or binding). Took the Jeep for a drive without the rear shaft, and the slight shudder / vibration was still there. However I noticed that I had to drive in Part Time as Full Time did not move. I am not sure if this is normal or that the transfere case is not working.

HoosierJeeper · **Joined:** Sun Feb 15, 2009 8:23 am **Posts:** 1218

That's normal. Fulltime routes power to the axle with the least resistance aka traction.

I'm thinking the u joints or intermediate shaft. Does turning seem to change it? See if there's play where the intermediate shaft connects to the right CV.

kj75 · **Posted:** Tue Jun 07, 2016 9:47 pm

Vibration occuring only on heavy acceleration at 1600rpm to 2100rpm, in 4th and 5th gear. With OD off it seems to be worse.
From what I have read failing inner cv shows the symptoms as well as a failing Auto transmission TC, and I want to find out which it would be more likely.

I have already removed the rear shaft to rule out rear shaft ujoint issues so it's not a rear shaft issue (vibration still evident with shaft removed).
Also dropped the transmission 1cm and vibration is reduced when Jeep is loaded with 3 adults.

The inner CV seems to have a very small play (1mm) when I wiggle it, but the boots are fine as there are no rips.

Any tips would be welcome.

mass-hole · **Posted:** Thu Jun 09, 2016 3:25 am

I also had an issue with the rear u joint on mine. I had some humming before I lifted my Jeep but it was greatly exacerbated after I put the lift in place. Same exact symptoms as you where it would make noise at around 70 kph and then again around 100. The first few times I went under to check I didn't see any signs of a bad u joint but the last time I check it it was about to come apart.

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kj75 · **Posted:** Thu Jun 09, 2016 12:33 pm

Seems I was mistaken about loading the Jeep and improving the shudder / vibration. I placed 140KG in the back, and shudder / vibration is still there.
I made a video recording to try and describe the noise.

https://youtu.be/bNcjKMZKDdo

Fabio_The_Jocker · **Joined:** Fri Mar 10, 2017 6:37 am **Posts:** 13

Hi, have you solved it? I have a very similar vibration

2006 Cherokee KJ vibration after lift

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