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Bad wobble between 45-55 mph.. Need help!! (long)

Talyn

NAXJA Forum User
I have been fighting a wobble between 45-55 mph (and comes back aroun 75 mph a bit) for the past 3 months. It gets worse over bumps, but at about 60mph is it perfect. It isn't death wobble though, but it is a heavy wobble (like pre-death wobble). It will wobble on a perfectly flat surface with no bumps.

My specs:
2000 XJ
3.25" front (spacers + ZJ V8 springs)
3.5" rear (RE AAL)
DT3000 shocks
JKS BPEs
JKS QDIIs
JKS Track bar
Yokohama Geolander II + 255/70-16 tires
OME HD SS
Stock CAs
I think that is it.

What I have done so far:
New left side ball joints
New u-joints in axle
New TRE at pitman arm
Removed front drive shaft
Had the alignment checked 3 times (will gives specs later)
Tires have been balanced several times by different shops.
I have swapped the front tires with another XJ with stock size tires.. wobble was better but was still there. He also detected no wobble running my tires on his XJ (would pint to my suspension).
I also swapped tires with PA Highlander and he also found nothing unusual with my tires on his XJ.. but I couldn't fit his on mine.
Also, swapped tires off a brand new Liberty and the wobble went away (would point me to the tires)
4 separate shops have found nothing wrong with my front suspension.. nothing lose at all.
The dealer put the XJ on jack stands under the axles and ran it into the wobble range, but found no wobbling.

Alignment specs:
Front:
Camber: L -0.5; R -0.4
Caster: L 7.2; R 6.9
Toe: L 0.02; R 0.01; Total: 0.03
Steer Ahead: 0.00

Rear:
Camber: L -0.3; R-0.1
Toe: L -0.21; R 0.19; Total: -0.03
Thrust angle: -0.20

All the specs ate good aside from the thrust angle... that is out .05* from spec of -.15 to .15. I will be rectifying that though, but would that cause a wobble?

I think I have listed every pertaining detail.

Any suggestions?

Thanx,
Chris
 
When it comes to "wobble",everything must be checked thoroughly! The rubber compound in the new XJ's ca's is extremely soft!
 
I was thinking that as well... they seem a bit easy to move by hand (but teh bushings are good).. I only know of one other person that is having the same exact problem as I am. Anyone think it could be teh CA bushings?
 
What do your tires look like? Are they worn down?
 
It has to be wheel balance...if teh problem recurrs @ set speed the wheel tire combo is out of balance...make sure your shop is blanceing to 75 mph...most only balance to around 45
 
xjnation said:
It has to be wheel balance...if teh problem recurrs @ set speed the wheel tire combo is out of balance...make sure your shop is blanceing to 75 mph...most only balance to around 45

It isn't... for several reasons.
1) A unbalanced tire (slightly unbalanced) would cause more like a vibe.. this is a true wobble.
2) I have had umm... 4 shops balance them... no difference
3) from initial post:
"I have swapped the front tires with another XJ with stock size tires.. wobble was better but was still there. He also detected no wobble running my tires on his XJ (would pint to my suspension).
I also swapped tires with PA Highlander and he also found nothing unusual with my tires on his XJ.. but I couldn't fit his on mine.
Also, swapped tires off a brand new Liberty and the wobble went away (would point me to the tires)
4 separate shops have found nothing wrong with my front suspension.. nothing lose at all.
The dealer put the XJ on jack stands under the axles and ran it into the wobble range, but found no wobbling."

-Chris
 
Steel or alloy rims? If steel, look at the possibility of having a bent rim.....or more than one bent rim. Second, check the shocks for play where they mount and for overall shock serviceability.

Tom
 
Have you checked for brake rotor warpage? Bent wheel? Try playing with air pressure, both up and down. What pressure are you running now? You're bound to find something loose in the front end that is allowing the wobble. As RCP Phx mentioned, control arm bushings could be suspect. Does the JKS track bar run rubber at both ends?

The dealers test, using jack stands isn't valid. The effective spring rate provided by tire sidewalls and tread squirm are eliminated with the axle rigidly mounted on the jack stands. This drastically changes the natural frequency of the axle/tire assembly which is a factor in the wobble. Swapping to different size tires has a related effect and should result in a change in the speed at which the wobble occurs.
 
MaXJohnson said:
Have you checked for brake rotor warpage? Bent wheel? Try playing with air pressure, both up and down. What pressure are you running now? You're bound to find something loose in the front end that is allowing the wobble. As RCP Phx mentioned, control arm bushings could be suspect. Does the JKS track bar run rubber at both ends?

The dealers test, using jack stands isn't valid. The effective spring rate provided by tire sidewalls and tread squirm are eliminated with the axle rigidly mounted on the jack stands. This drastically changes the natural frequency of the axle/tire assembly which is a factor in the wobble. Swapping to different size tires has a related effect and should result in a change in the speed at which the wobble occurs.

Well, if it was a bent wheel it would have shown up on the other XJs they were on. I iwll try the air pressure.. it is currently at 30psi front, 29 rear. Te JKS has rubber at one end but i don't know what exactly to call the large ball type bushing at the frame side.

I took into account the speed change in the smaller tires. Tested it under and ove rthe speed range it happens.. all the way up to 85 mph and it was fine.

As for teh brakes... it doesn't really act like brake rotors... it is there regardless of wether the brakes are applied or not, It goes away after a certain speed, but if the speed is dropped (coasting) the wobble will return even without braking, and I can hit the brakes out of the 45-55 mph range and there is no wobble. I will, however, put some stock rotors on tomorrow just to verify.

-Chris
 
Talyn said:
1) A unbalanced tire (slightly unbalanced) would cause more like a vibe.. this is a true wobble.

I disagree. "Vibes" are vibrations -- they are fairly high frequency, small amplitude oscillations. There is simply no way that an out-of-balance tire and/or a bent wheel rim can cause anything remotely similar to a vibration.

MaXJohnson has a good suggestion in looking at rotors and bearings. The only time I experienced true death wobble was in a totally stock 1999 WJ (Grand Cherokee) with about 10,000 miles on the odometer at the time. What set off the episode of DW was a warped front rotor.
 
Oh yeah, I forgot to mention the rotors. I just went through this with rotors that were bad from the get-go.

Tom
 
Brakes are good.. put some new rotors in and the wobble is still there. Bearings are good as well. Replaced the control arms bushings with some ones I had laying around (from a previous XJ that I never got aroudn to install them on). Wobble a bit better, but still there.

-Chris
 
Are you the original owner of the XJ, just asking if it may have had any damage repaired from a wreck.

You mention wobble, where on the scale is it. 1-10, 1 being bad road, to 10 being I'm going to die. Has anyone else test driven your XJ?

The only advise would be to look into some LCA's, your specs look good as far as caster, but maybe your tires are not centered propperly. Also using the ZJ springs and spacers with the OEM LCA's maybe keeping the suspension from moving through the proper geometry.
 
XJCHUCK72 said:
Are you the original owner of the XJ, just asking if it may have had any damage repaired from a wreck.

You mention wobble, where on the scale is it. 1-10, 1 being bad road, to 10 being I'm going to die. Has anyone else test driven your XJ?

The only advise would be to look into some LCA's, your specs look good as far as caster, but maybe your tires are not centered propperly. Also using the ZJ springs and spacers with the OEM LCA's maybe keeping the suspension from moving through the proper geometry.

I am not the orginal owner, but bought it at about 28,000 miles.. no signs of any accidents.

The wobble is about 6. A few people have test driven it and found it abnormal. It also can happen on a level road with no bumps.

If the wheels aren't centered ( I am assuming you mean length wise) I would also need UCAs as well. Right? I am not seeing how LCAs would help here since the bushings in my stock LCAs have just been replaced.

-Chris
 
Talyn said:
[What I have done so far:
Also, swapped tires off a brand new Liberty and the wobble went away (would point me to the tires)

Chris,

I applaud you on your thorough investigation!!!!!!!!

I would have said tire balance, until I read your original post. Then I thought wheel balance, until I read your post again. The Liberty wheels and tires, and the fact that you have swapped rims and tires with other Jeeps is what's throwing me off. I wish I could help.

What rims are you running anyway?

Flowers
 
Re: Re: Bad wobble between 45-55 mph.. Need help!! (long)

Flowers said:
Talyn said:
[What I have done so far:
Also, swapped tires off a brand new Liberty and the wobble went away (would point me to the tires)

Chris,

I applaud you on your thorough investigation!!!!!!!!

I would have said tire balance, until I read your original post. Then I thought wheel balance, until I read your post again. The Liberty wheels and tires, and the fact that you have swapped rims and tires with other Jeeps is what's throwing me off. I wish I could help.

What rims are you running anyway?

Flowers

Ummm.. don't know the name of them. They are the 16" rims that came on the Limited and Classic models. Pics on my website in sig.

Yes, swapping the tires is very confusing. My tires behave fine on 2 XJs, while one pair of front tires still has the wobble, but all 4 from the Liberty have not wobble.

Someone mentioned that a DPA maybe needed.. but this happend on a nice level road with no bumps as well.. so not a lot of steering changes. The JKS track bar does drom the stock piviot point by about an inch, but both the draglink and track bar appear to be parallel. Maybe I should try a ZJ pitman arm? It shouldn't be too much$$.

Ugh.. I must be missing something.

-Chris
 
I can proboly slove your problem i had the same problem on my 01 tried evrything new DS new wheels adn tires whole sooting mathc and the only thing that sloved it was when I put Rusty's LCA from my old 4.5" lift that have the poly bushing. It drives better than it did when i got it new...
 
This is something to check, I don't know how old your XJ is, but I had a similar problem of pre death-wobble.

It turns out, all of my grade 8 factory control arm bolts, were seriously worn out. They were actually necked down from thier original size. Also check your steering stabilizer bolt.
 
Talyn said:
I am not the orginal owner, but bought it at about 28,000 miles.. no signs of any accidents.

The wobble is about 6. A few people have test driven it and found it abnormal. It also can happen on a level road with no bumps.

If the wheels aren't centered ( I am assuming you mean length wise) I would also need UCAs as well. Right? I am not seeing how LCAs would help here since the bushings in my stock LCAs have just been replaced.

-Chris

The length is exactly what I'm talking about. At that hieght just over 3", also you have the spacers, I'm not saying they are bad, but when your axle isn't centered over the spring mounts may be causing your wooble. I know when I was at 3" adding longer LCA's made my XJ more stable. You have done a really good analysis, I'm thinking either there was an accident or your at the point for LCA's. Your caster will change, if your worried get UCA's to boot. Go to the classifieds for cheap used stuff.
 
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