Is my ZJ having death wobble or something else?

My high mileage '96 ZJ Grand Cherokee has recently developed a problem that started out mildly annoying, but is becoming a real concern.

Every so often I'll hit a pothole or rough spot on the road, especially a rut, and the front end starts a shake that at first feels like a badly out of balance tire, but sometimes escalates to a nasty shake through the whole front end that I can feel in the steering wheel. It seems that a bump to the passenger side front wheel sets it off much quicker than one to the driver's side. Sometimes a quick stab of the brakes makes it stop. More recently that hasn't been as effective, and it's been taking less of a bump to start the shake.

It doesn't help that the shocks are worn out no name brands and the brake rotors are well past due for renewal.

I had the front wheels jacked up the other day and didn't find anything wrong with the steering linkage or front control arm bushings. The control arm bolts seem perfectly centered in the bushings and I find see any rips or distorted parts in the rubber. The ball joints feel tight. All the steering components have grease fittings and take grease. I'm not sure how to check the rod (track rod?) that runs from the frame diagonally down to the axel beam. It feels tight, but I have no idea if I'm inspecting it correctly. I could see a problem in that rod being easily felt in the wheel. It does have a steering damper, it looks like factory original, and may be leaking, it's hard to tell since the engine leaks oil on it. My gut is telling me it's not because of the damper, but I could be wrong. This is the only vehicle that I've ever owned with a solid beam front axle, so this is new territory to me.

Sounds like death wobble to me. First time my K30 did it I about E36 M3 myself. In my case the kingpin bushing was cracked. From my research any worn component could cause it.

I saw this happen to my buddies xj.

If it's death wobble, get it fixed NOW.

That E36 M3 looks scary!

Sounds like death wobble, and it probably does need a new steering dampener, but that's not the solution. Balance and alignment are large contributors, but with the age, I'd wager the track bar (panhard) bushing is shot.

All the clevite bushings are probably shot based solely on age. They're a big enough of a bear to change, that it makes replacement control arms worth while. That doesn't save you from having to replace upper axle end bushings though, not the worst job, but still far from fun.

Replace the steering dampener (oil leaking out, air leaking in). Your vehicle has a high positive caster setting (7 degrees preferred) which causes the condition you are experiencing if not controlled by a dampener.

In reply to outasite:

BullE36 M3. With the caster cranked to at least 8* on my ZJ, it drives perfectly fine if I pull the damper. It's not an oscillation prone steering system unless something is wrong.

Replace all the tie rod ends, make sure there's no play at all in the track bar or ball joints. Then check the control arm bushings. Once nothing has any play at all, get it aligned and it should be solid.

You probably have a worn tie rod end somewhere. Also if it has the cheap coil spring spacer lift kit but no drop pitman arm it will happen.

Everyone's saying the same thing, that you have play in your front suspension pivots. Inspect and start replacing the worst, or honestly, consider replacing all of them at one time.

is it lifted? Could be the death wobble. But at the Jeep dealer, I must have put in 100s of steering stabalizers.
Death wobble is more speed-related, worn shimmy shock is bump related. They're cheap.

In reply to moparman76_69: No lift, completely stock, no serious off-roading, unless PA roads count, and they probably do.

In reply to DrBoost:

Is there a preferred brand of damper for an otherwise stock Jeep? Any brand that should be avoided?

Damper is not the answer, damper is a band aid that at best might mask underlying worn components. Find and fix what's worn, then add a new damper too, get a proper alignment and make sure the tires are wearing evenly and balanced.

I've used Monroe, Doetsch, Gabriel, and Rancho steering dampers, no discernible difference between any. The Monroe and Gabriel stuff will be direct fit, with the proper tapered bushings for direct OE replacement.

Considering the high mileage I wouldn't mind replacing all the tie rod ends, the damper and maybe the track rod, and following that with an alignment and wheel balance.

It sounds like what Dr Boost is saying is that I should try just the damper first.

In the time that I've had the Jeep, it's greatest strength has been that it's cost me so little money to operate. It's definitely had some issues, but nothing that's cost more than a couple hours of my time or more than $100 (battery). Oh wait, I just remembered I replaced the whole exhaust system, cat and both O2 sensors, so make that $350, still stinkin' cheap compared to the eurotrash that I usually own.

I just hope that this doesn't turn into a downward spiral of costly repairs for a vehicle that I don't have any real affection for.

If wanted a domestic SUV, I'd buy an SBC powered Suburban or Tahoe. ( GM truck parts available on the cheap in every town in the Western hemisphere FTW!).

SWMBO, who drives it most often would choose an Exploder or Expedition. I like FoMoCo too, well except for that modular engine/ SOHC 4.0 v6 business . If I could find a low mileage, really clean 5.0 SBF Exploder/Mountaineer I'd go for that too. Those aren't easy to find around here anymore.

That being said, it's impossible to hate the 4.0 Jeep engine, I just wish that I could say that about the rest of the truck.

In reply to bigdaddylee82:

Tire wear has not been a problem on this truck. I keep them at 40psi and rotate them front to back every 6 months.

The fact that they are harder than rocks Coopers may have something to do with that though.

The damper isn't necessarily a band aid. It's there to quell the side-to-side forces that you get when hitting a bump, primarily with one front wheen before the other. It's just a shock absorber, so they leak and wear out.
The issue could be exaggerated by worn steering components though. While your at it, adjust the steering gear box. There's a jamb nut in top. I don't follow the overly complicated procedure in the FSM, I just remove the slop I can feel and it's night and day. As far as brand, the end result will be the same between cheap and expensive brands. The cheap ones will just wear out sooner.

The stock system isn't oscillation prone even without a damper. If there's no play, it takes a lot to make is oscillate. WJs are a different story there, so if you ever deal with one of those, make sure the damper is good.

On a ZJ, IMO, the damper is the last part that should be touched when death wobble is an issue as it won't fix anything, it's just an extra layer of insurance.

Also, for whoever mentioned a drop pitman arm, you only use those if you also have a drop track bar bracket. As long as the track bar and drag link are parallel, you're good. If they're not, you get nasty bumpsteer.

I just went through and did a complete refresh of the suspension in my XJ earlier this summer, along with the install of a lift kit. A gradually worsening death wobble, much like what you are describing, was what prompted that project. It felt like a whole lot of mass

I agree wholeheartedly with Lee. Assuming decent alignment and tire balance, track bar bushings would be my first suspect, followed closely by tie rods ends and ball joints. Do the front bushings on the upper control arms while your track bar and steering linkage are disassembled, it will be a whole lot easier to access them. If you're keeping everything factory, the control arms that come with the bushings already pressed in really aren't that much money, IIRC like $15 or $20 a pop at Quadratech.

The damper is the last component I would replace, to be sure it isn't masking any further underlying issues.

I guess all my years in a Jeep dealer, building more than a few Jeeps, and ASE certifications are wrong then.
Naturally, I can't diagnose an issue over the internet with a certainty, but given the mileage and my experience, replace the shimmy shock and inspection the test of the system.

In reply to DrBoost:

DrBoost, I'm not trying to discount you're knowledge or credibility, the steering dampener does serve a purpose, but when "death wobble" presents itself in such a manner as Andy describes, all my years of building more than a few Jeeps tells me there's a larger underlying issue.

A new damper might reduce it, could even mask it to the point that you don't notice it as often, but it ain't going to fix it.

FWIW, my experience with my 1997 ZJ (only 80K miles at this point) has been the same as Dr. Boost. Cheap and easy steering damper replacement and steering box de-slop got me back to 100%. I seem to need a new damper about every 8 years. The second time it happened, I asked the hive for advice about a more expansive remedial plan, and I got plenty of good advice, which I appreciated at the time and still do. If the damper swap ever lets me down, I will know what to chase next.