Wobble when going over uneven road at speed

[SnowDrifter]

I believe I've tracked it down to the change in left right position in the rear axle as the panhard bar goes through it's stroke. The thing swings in an arc and changes in rear suspension height will also cause a change in side to side position of the rear axle. Really feels crappy when I'm going >80. The roads here have some large bumps and dips. They're not rough, but they feel a bit like riding on a roller coaster at times hah

So... With that in mind. Any easy fixes short of going to stiffer suspension to minimize the travel? I really like how it rides and I'm loathe to change it. Or I guess I should ask: Any practical ways of going about this short of fabbing up a watts-link system? That's not something I have the time or funds for right now.

 

[Doubeleive]

is your vehicle lifted?
normally there is rear torsion bar unless you replaced with a panhard bar, either way if it's worn out maybe replace it, adjust it tighter, or make sure the bolts are tighter but normally that just stops any clunking noise
maybe upgrade the rear sway bar?
replace shocks?

 

[SnowDrifter]

Perhaps panhard bar was the wrong word. Track bar? I can never remember the proper name of that darn thing.

The vehicle is bone stock.

Replaced shocks when I got the vehicle as they were leaking. Rears were replaced with OE HD non auto-leveling. Fronts are Napa OESpectrum. Front inner, outer tie rods, pitman arm, idler arm, idler arm bracket were all replaced with moog. Upper/lower ball joints and control arm bushings are original but were checked for play.

Rear control arm and track bar bushings were visually inspected and checked for play

 

[SnowDrifter]

This guy

 

[LINTZ0718]

This guy

Just ordered that same bar!

 

[Chubbs]

if your vehicle was originally an auto leveling or smooth ride RPO code the problem could be with the rear springs. For sure on the zw7 suspension package, softer OEM springs are used with the Nivomat self adjusting shocks. When said shocks are replaced with standard units, the springs must be replaced as well since the originals would be too soft when applied with regular shocks. A harder, more heavy duty shock would exacerbate the issue concerning an improper pairing of shocks & springs. My suggestion is to replace the springs with a firmer part if the track bar bushings R&R didn't improve the handling. Inspecting the rear sway bar bushings and links also comes to mind considering their role in axle stability but you already ruled that out. I would look for anything which may have been deleted by a previous owner, as well.

It's just my opinion but the track bar itself shouldn't make a difference in the handling on a stock application in typical daily driving scenarios. The only time track bar plays a part would be when lowering or lifting the suspension and the axle shifts 1 way or the other. Drop brackets or extension brackets, and adjustable bars are used with suspension modifications to correct the axle shift 'phenomenon' as some would call it.

Not for nothing, but coil springs are a wear/replacement item that can become faulty with age & repeated loading, especially under extreme conditions. You would need to remove the shocks and test the compression of the rear end to disregard the springs as a factor altogether. Another condition that would affect the handling of your truck is a shock that is too tall or short for your given suspension height; a shock that is not allowed to operate within its design perimeters could cause the symptoms you have discussed, albeit pretty difficult to miss during installation process in extreme cases. This is all I can think of, please report any findings or repairs and results.