Wobble/shimmy at 30 then 60MPH, *not* tires - help?

[Nixt]

1995 XJ VIN with 1996 registration and interior trim.
UpCountry package, stock everything.
4.0, AW4 with oil-cooler, NP242, D30.front, D35C.Trac-Lok.rear, 3.55 ratio.

Issue:
-Wobble/shimmy that "feels like" a wheel balance issue.
-Sensation is mostly felt through feet, very little steering wheel sensation.
-SLIGHT increase in sensation when accelerating, no change when braking.
-Wobble is felt very slightly at all speeds above 25 MPH,
but is a *very* noticeable wobble/shimmy at near two speeds:
30 MPH and another at 60 MPH.
(Speedo is in KM, so it's 45 and 95KPH).

What I have done already:
-Rebalanced wheels. Guy said one was out but not horridly so, the others were out barely. No change with this wobble/shimmy except the two speed ranges increased slightly from 25 to 30 MPH and from 50 to 60 MPH after the rebalancing. (40KPH wobble moved up to 45KPH and the 80KPH wobble moved up to 95KPH) ... WTF, right?
-Did a "wiggle check" on suspension and drivetrain parts under the heap. Old, sure, worn... some bits can move more than they probably should, but nothing seemed 'loose' for a '96 with original components.(*more below)
-Noticed that the shocks are near dead, but 'not dead yet'. (Monty Python, anyone?)

Any input or suggestions would be appreciated!

Thanks!


(* the 'more' part: I have recently been under this heep to find a worse wobble - caused by a loose nut on the front output yoke of the transfer case - solved via help! http://www.naxja.org/forum/showthread.php?t=1055535 You guys are awesome.)

 

[AaronsJeep]

Issue:
-Wobble/shimmy that "feels like" a wheel balance issue.
-Sensation is mostly felt through feet, very little steering wheel sensation.
-SLIGHT increase in sensation when accelerating, no change when braking.
-Wobble is felt very slightly at all speeds above 25 MPH,
but is a *very* noticeable wobble/shimmy at near two speeds: If you didnt feel it in the steering wheel then it's probably not the tires. Have you looked at the drivelines/U-Joints?

 

[Nixt]

Aaron-
Posted in the thread starter that I did a wiggle check under it while chasing another issue.
Nothing seems out of sorts to me, but I am not exactly expert on this stuff.
The mechanic I took it to for that issue also did not note anything awful, just old and worn.

 

[Nixt]

Bumping the thread, sorry.

Please? Anyone?

 

[jap813]

I had a rear u-joint that the wiggle check did not reveal any issues, however when I pulled it apart the bearings where dust, nothing left, replaced and vibe was gone

 

[whitexj98]

You said you did the wiggle test but did you have some one turn the wheel back and forth while you look at all tie rod ends and especially track bar ends for any play ?

 

[Robs92XJ]

Have you had an alignment? If bad alignment and wheel balance have been ruled out, that basically leaves the driveshafts and u-joints. First thing to try is pull the front shaft out and test drive. If the problem goes away it is something to do with the front shaft. If not, take a close look at the rear shaft. It is best to remove it, and check the movement on the u-joints. Also look for signs of missing weights on the shaft. Might take it into a drivetrain shop and have them balance it, around here it is pretty cheap. When you re-install it grease up the slip yoke really well.

There are lots of bits in the front end that can wear and cause shimmies and death wobble, but its usually felt in the steering wheel. I'd be looking at the drivetrain.

 

[Nixt]

jap813 - Dust, huh. Well maybe I need to look closer.

whitexj98 - No, but will this wkend.

Robs92XJ - It measured up fine last I checked it (couple months now) - less than a mm out. (Garage-style method, two rods - extend, clamp, relocate and compare...)

OK, all: I have a weekend plan-
1) checking all bits in the front with someone bumpstopping the wheel.
2)Pull rear shaft and check ujoints and balance/straightness.

 

[jap813]

yes dust no needle bearings left in it, but it felt tight when doing the wiggle test

 

[whitexj98]

jap813 - Dust, huh. Well maybe I need to look closer.

whitexj98 - No, but will this wkend.

Robs92XJ - It measured up fine last I checked it (couple months now) - less than a mm out. (Garage-style method, two rods - extend, clamp, relocate and compare...)

OK, all: I have a weekend plan-
1) checking all bits in the front with someone bumpstopping the wheel.
2)Pull rear shaft and check ujoints and balance/straightness.

Also keep the vehicle on the groud while doing the check you want the weight of the vehicle on everything.

 

[RCP Phx]

It measured up fine last I checked it (couple months now) - less than a mm out. (Garage-style method, two rods - extend, clamp, relocate and compare...)

Ive never found that method to be very accurate,scribing the tire will get you better results.

 

[Nixt]

Update and thread closer:
It was the ball end on the Panhard rod / track bar.
With nobody else to turn the wheel while I was under it, it took a while to isolate the issue.

Thanks all for the input!