Riddle me this?

p m

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Apr 19, 2004
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The vehicle in question is a 95 LWB Classic, but I decided to stick it here for more opinions.

The issue: something that manifests itself like a wheel shimmy.
Caveats: it comes and goes, and rarely if never - in a turn. Almost always - during straight-ahead driving.

Alignment - nearly perfect. The truck tracks and handles very, very well.
Panhard rod bushings: checked tight.
TREs: checked tight.
Wheel bearings: checked very tight.
Swivel ball preload: adjusted tighter.
Pitman arm play: checked, none.
Steering box bolts: checked tight.
Steering box play: checked, nearly none.
Steering shaft play: checked, nearly none.

It feels as if someone pounded in the bearing race into the hub crooked, and the wheel wobbles as it turns; Jimmy (jymmiejamz) rightly suggested checking the wheels for being straight - on the rim, they are within at least half a millimeter. No out-of-round on the XZL tires, either.
I should also mention - this truck had this shimmy when I bought it, three sets of wheels (two different sets of alloys and Wolf steelies) and tires (BFG A/T, some other all-terrains, Michelin LTX) ago. Balancing the tires does not eliminate it.

The vibration is considerable enough to wiggle the ABS sensors eventually. I can live with it, but it'll likely destroy something else.

Any ideas?
 

p m

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Apr 19, 2004
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Runout verified along the rim circumference. Less than 0.5 mm - typically far less than tires being out of round.
Have not checked bolts between the swivel balls and axle housing - methinks if they were even a little loose, they would've worked themselves out already. Besides, no oil leaks from the axles.
Panhard rod bolts and bushings solid - meaning zero relative motion between the rod and the parts it attaches to.

I wonder if one or both front shocks has gone bad.
 

p m

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Apr 19, 2004
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Shake down the rear axle. Look for any play in your trailing arms and bushings.
Will do - but in my experience, any play in trailing arms bushings would result in erratic handling, and this truck is exceptional.
I have not yet ruled out runout on the rear hubs or wheels, will look at it as well.
 

Jimmy

Well-known member
Apr 10, 2006
636
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Aurora, CO
I lost my front end wobble (didn't reach death wobble status, but it was close) via rebuilding the swivels and new wheel bearings. Since I did both at the same time, I couldn't say if it was one or the other... or both. What I do know is that I adjusted my swivel preload tighter via the pull-a-shim method a couple years ago (due to having full blown death wobble), and I don't think I did myself any favors. When I did the teardown, I went to just the swivel and knuckle (removing the swivel ball seal) to check what it felt like when rotating... and it felt like crap. It was herky-jerky and too tight on at least one side.
 

lunchbox

Well-known member
Apr 20, 2004
1,861
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St Louis, MO
It sounds like you’ve done the normal stuff one would expect to cause wobble. Did you actually look at the upper and lower swivel bearings? That upper one is garbage and will die. My experience with running heavy ass Interco tires was that they amplified any small issue. The weight and lack of road worthy build really wore shit out. im sure those XZL are similar. To address your shock question, I did have a blown OME shock cause crazy death wobble on the highway. I was getting on from the ramp and had to pull off the road. The drivers side shock was junk.
 

lordhelemt

Well-known member
Dec 18, 2010
56
3
Had a similar issue on my LWB. Swapped out the radius arm/trailing arm bushes, sway bar and tire rod end bushes, set the preload on the swivel balls, etc. rode tighter but would still vibrate on occasion. Gave a closer inspection on the shocks and notice some play in the shock bushings. Replaced those and the truck drove like new.
 

CORover

Well-known member
Jun 11, 2007
719
54
Colorado, USA
While you are checking shocks, check your steering damper, not sure if it has one, shoiuld be like a D1. I have replaced several only to find that it did not fix the issue, but it is always first on the list of things to check.
 

p m

Administrator
Apr 19, 2004
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Happens at highway speeds or any speed regime?
Starts around 55-60.
More and more, I suspect one or more blown shocks - super easy to check, but goddamn the daylight is short.
Swivels - I did replace the upper pins and bearings about a year ago. It didn't change anything.

It is not a "death wobble" - at least, it is neither triggered by potholes nor it happens in a turn.