Jeep JL Death Wobble

[Gasbuggy]

OK... I guess i don't understand the strong aversion to working on the girlfriends truck... she's probably thinking she will end up cleaning your house or having to diagnose all you and your friends little coughs and scrapes...

Or was this just a humble brag that the GF is a doctor?

Ha, I was glad she wasn't likely broke as a joke but I was thinking more that she wouldn't tolerate something keeping her from getting to work.

I don't mind wrenching, it's the rabbit hole projects on cars I wouldn't buy that I'm tired of.

 

[Gasbuggy]

Sounds like she has the money for the additional warranty and it works out well for everyone. Life’s too short to be messing with other peoples crap.

The warranty was surprisingly cheap. It was $2700 for 4 years/60,000 additional bumper to bumper miles. So it's covered till about 110,000.

 

[Gasbuggy]

Here is a list of components that actually cause death wobble in live axle / coil sprung front suspensions:

1. Tracbar
2. Tracbar
3. Tracbar
4. Tracbar
5. Tracbar
6. Tracbar
7. Tracbar
8. Tracbar
9. Tracbar
10. Tracbar

Actual death wobble is the axle itself moving side to side. It's an oscillation caused by failure of the lateral link that manifests itself in the axle steering itself left/right very quickly on it's own as severe bump steer.

The panhard bar / tracbar / lateral link has two purposes. 1 is to prevent bump steer as the axle moves up and down throughout suspension travel by keeping the draglink attachment point a constant distance from the end of the pitman arm. In a LHD vehicle, as the axle moves up, it will move slightly to the right. As it goes down, it moves slightly to the left. It's an arc.

It also provides lateral mounting for the axle. To keep it centered under the vehicle.

IF the tracbar and drag link are not at the same angle (caused by someone throwing aftermarket lift parts at it without supporting mods or worn out bushings / mount brackets / components) *any* movement in the front suspension be it up/down or left/right will feed back through the steering wheel.

What happens with actual death wobble is you hit a bump, or an out of balance tire hits the right resonance and the axle moves. Okay - normal. The problem is, when that happens, instead of the tracbar taking the load and keeping the right knuckle an exact distance from the pitman arm, it doesn't ... And you feel it through the wheel.

So - you hit a bump. Slop in the tracbar bushing. The axle moves straight up instead of up and to the right. That pushes on the draglink. Your hands are on the wheel, and you feel a bit of feed back. But what that also does is steer to the right a bit. Now the axle starts to turn right. But because the bushing has slop in it, instead of the vehicle turning, the axle moves over. Now it's pulling on the drag link and you feel the steering wheel tug to the right. But because you have a hold on the wheel, the weight of the axle and the vehicle pushing on it, cause it to push on the drag link ... rinse, lather repeat.

I've had a few jeeps that death wobbled. You either slow down or mat the gas pedal and power through. For a period, my Cherokee would death wobble at 55. If it triggered, I'd speed up to 60 or slow down to 50.

You can balance the tires to maybe prevent the trigger. People do steering stabilizers to prevent the bump steer portion. That's minorly successful.

Ultimately, death wobble can ONLY be a failure of the lateral link.

I don't know about the Ford trucks, but in the Dodge trucks and Jeeps, the mounts are comically undersized. Every death wobbling Jeep I've worked on that still death wobbled AFTER putting on a new tracbar or bushings was from the axle side mount egging out. The mounts are like 1/8'' sheet metal. Terrible design.

It's either a mount, a bushing or there is a drop pitman arm / relocated tracbar bracket causing the bump steer.

I appreciate you writing that all out. 1. So I understand it and 2 so I can make sure it gets fixed correctly.

 

[svtrit]

Reminds me how they say "Jeeps are the best offroaders if you replace the wheels, tires, axles, suspension, gears, fenders and give the engine and Trans a tune"

Stock with street tires. It went everywhere the lifted 4 Runner with AT tires next to it went. Wheels are black with mud from creek crossings.

 

[jeepman3071]

Reminds me how they say "Jeeps are the best offroaders if you replace the wheels, tires, axles, suspension, gears, fenders and give the engine and Trans a tune"

They are surprisingly capable in stock form. Since they are easy to customize and build, the modded ones really depend on who is building them and the parts used. I've seen some amazing builds that are very capable offroad and actually drive better on the street than stock. I've also seen many more that are horribly dangerous and built with shoddy parts that I wouldn't feel safe driving over 15 mph.

 

[LouC]

That’s a good summary of what you see in the used Wrangler market. If I were buying one for myself I’d always want to start with a stock vehicle. I’m not paying for other peoples mods that I have to now remove & redo. There is a good reason why in Australia one of the biggest 4x4 markets in the world; suspension lifts are limited to 2”
or 50mm. Beyond that you have exceeded the limits of most 4x4 suspension design as far as on road safety

 

[SwampSurvivor]

They are surprisingly capable in stock form. Since they are easy to customize and build, the modded ones really depend on who is building them and the parts used. I've seen some amazing builds that are very capable offroad and actually drive better on the street than stock.

A base model off the dealer lot is more capable than my 2000 Cherokee with lift, gears, locker, tires, etc. The difference is the fear of body damage.

I've also seen many more that are horribly dangerous and built with shoddy parts that I wouldn't feel safe driving over 15 mph.

That's now mine Since getting a trailer it's pretty much trail only at this point.

 

[Shel_B]

Here's a video about it. Might be helpful:

 

[atikovi]

Is "death wobble" a thing with Ford twin I beam suspension? My '03 Econoline wagon has the shakes around 30 mph and between 62 to 70 mph. And it isn't consistent as sometimes it's perfectly smooth at those speeds.