• NAXJA is having its 18th annual March Membership Drive!!!
    Everyone who joins or renews during March will be entered into a drawing!
    More Information - Join/Renew
  • Welcome to the new NAXJA Forum! If your password does not work, please use "Forgot your password?" link on the log-in page. Please feel free to reach out to [email protected] if we can provide any assistance.

Vibration

ScoutXJ

NAXJA Forum User
Location
Roanoke, VA
Ok guys, I know this question has probably been asked and answered in the past. But in the slight chance it has not been answered then if anyone knows of a starting point please fill me in. Please don't say use the search option, because I have tried that and it has led me to a bunch of "Death Wobble" posts. I do not believe that it is that.

So, I have a 90 XJ with a 97 rear end and 94+ 5 speed AX-15 (guessing year because of external slave cylinder), it has been lifted 3.5-4.5 inches (not sure on the exact lift because it was bought that way).

It has developed a vibration/ bouncing feeling while taking moderate to sharp turns about 25 mph. I have been unable to determine a possible location/ source of this. I can fill it more in the seat / pedals / lower back / ass than in the steering wheel. From my past mechanical experience this isn't caused by steering, which is usually the cause of the "Death Wobble".

Now, this began last week, which is when I reinstalled the engine in the vehicle. I replaced the engine mounts before it was reinstalled. I haven't checked the mounts yet to ensure they are still tight, I was hopping to do that tomorrow. But I would like to know if anyone else has experienced this problem, fitting the description that I have provided. I have been driving this thing for about 7 months, and this is the first time it has done it. There was never any onset of vibrations leading up to this.
 
Couple things I would look into if this was happening to me.....
One would be to look at the ball joints.
Get the front end up one corner at a time, grab the wheel in the 12 and 6-o-clock positions and try to push it back and forth in that axis feeling for play....do the same thing in the 9 and 3-o-clock positions, working it back and forth, feeling for play. (helps if the steering wheel is locked for these.)
I would also tak a look at the u-joints.... if they've never been replaced, might be a good time to do so.
The wheel/unit bearings would be another thing I would look at, harder to test these, as you could have a bad one, and it not give you any play.
Wheel hop could be another issue....this would be caused by a bad shock.
Hope this gives you some starting points, and some things to consider.
Good luck.
 
Okay, I have replaced both of the U-Joints on the rear ds, and removed the front shaft. I checked the ball joints in the front and they were still fine. I looked over the front suspension and went ahead and tried to tighten any bolts. There were not any that weren't tight.

As I was looking over the rear of the vehicle, I did notice some play in the axle, it was rebuilt about 7 months ago, but there was about 1/8" of play in - out, and 1/4" of play rotating front to rear.

Also I do have a bent driver side rear shock, but it has been bent for as long as I have had it and it has never caused a problem.

When I was reinstalling the engine, the bolt that I was hoisting from on the ac mount broke and the engine fell, luckily it was only about two inches due to I was positioning it on the mounts. It landed on the mount and did not appear to have made contact with any suspension components.

I am stumped still. Like I said before, this has only been happening AFTER reinstalling the engine.
 
maybe your springs are sagging and the axle isn't properly shimmed, causing something to bind alittle. Mine does this when I tow my boat around and go fishing all the time. If it is coming from the rear of the vehicle, I would say its somewhere in the rear of the vehicle. check your shackles too. and anywhere the rear suspension welds up to the body. btw I can't keep a good shock on the rear passenger side of mine cause when I replace it it blows, either from towing or crawling, and I don't have this vibration.
 
Okay, so I put a nut on the motor mount and it seemed to lessen the vibration while in the corners. I also noticed that my left rear tire is missing a wheel weight. Could be the cause which kinda makes sense because it does it past a certain speed. All of the suspension components seemed to have checked out minus the bent shock, but like I said that has been bent for a while.

Tomorrow I am going to go and get my tires balanced and see if that fixes my problem. If not then I can cross of another item and continue from there.

Thanks for the responses so far.
 
Back
Top