LandRover Death wobble

[GregLocock]

I am told that live front axle LRs of a certain vintage may suffer from the death wobble popularised by Jeep. Rumor has it that on the Landys this is due to to worn bearings/shafts in the steering box and that reshimming may fix it. Has anyone worked on this?

 

[cibachrome]

Shimming may quiet it down simply because this adds some friction in the steer/ride mode. A higher flow rate pump can work as would a more responsive steering valve if power steering.
The fundamental problem is the tierod slope in front view. Change the height of the steer arm ball off the gear's Pitman arm to reduce the positive feedback. Many resort to an actual steering damper to change the critical damping level. This is also a patch on a systems problem. Increase the tire air pressure or go to radial tires to reduce tire Mz.

 

[mfgenggear]

so this an interesting subject. as i once purchased a used 2006 jeep with very low miles.
question! is this an inherent design flaw?
is it due to the forces , vibration, excessive wear, not robust enough to prevent radical vibration.?
I had two option complete rebuild of the front end with after market components. that was stiffer, more robust. bigger diameter, or larger
components. that prevented aka death wobble.
when I purchased this vehicle I drove it to work I was going the speed limit of 65 miles per hour. I hit a small pot hole. and I experience the scary death wobble.
not a fun experience.

 

[GregLocock]

@cibachrome thanks.

When new the live front axle LandRovers were safe to drive at any feasible speed, so we know it is a wear thing, perhaps excited by poor geometry

 

[BrianPetersen]

On Jeep Wranglers it's usually the front axle track-bar to body attachment - either the bushing is shot, or the bolt has loosened and allowed the hole in the bracket to be ovalled out. But, loose connections anywhere in the steering or suspension arms can cause this, and you're supposed to inspect everything.

 

[mfgenggear]

On Jeep Wranglers it's usually the front axle track-bar to body attachment - either the bushing is shot, or the bolt has loosened and allowed the hole in the bracket to be ovalled out. But, loose connections anywhere in the steering or suspension arms can cause this, and you're supposed to inspect everything.

So should of had a front end inspected, R and R

 

[LostInTransit]

No matter what the car or truck, at some point in its lifetime it will have a death wobble or just a bad vibration.. and several factors may contribute to this.. bad alignment, bad balancing, poor ball joints and bushings, even the brake rotors could be off kilter or you wheels are hub centric instead of lug centric... often this also means having to replace the entire front end just to isolate where the issue really is.

 

[cibachrome]

No matter what the car or truck, at some point in its lifetime it will have a death wobble or just a bad vibration.. and several factors may contribute to this.. bad alignment, bad balancing, poor ball joints and bushings, even the brake rotors could be off kilter or you wheels are hub centric instead of lug centric... often this also means having to replace the entire front end just to isolate where the issue really is.

But these are just patches to a systematic problem of positive feedback in the suspension geometry activated by tire and road inputs.

 

[mfgenggear]

I have owned many different vehicles that had high mileage. and never had vibration issues . such as the dreaded death wobble.
so what is the diffrence?

 

[LostInTransit]

As far as I know, no one has ever zeroed in on what the issues is or was.. but on a truck we use to have.. we had to replace the entire front end, new barring, bushings, tie rods, control arm and steering damper. As another fellow said above, it all deals with the geometry of the the suspension. I've never been able to isolate the actual cause, but I'd end up spending 3K for a new front end and the shimmy/wobble would go away. I recall a time when the F150 had a shimmy direct from the factory. Plus just to add to my comment above, some tires can not be balanced on particular wheels.. no matter how hard the tech tries. Install larger off road tires, you're asking for wear issues down the road which could turn into the shimmy. The steering wobble is directed more towards the bushings or ball joints. Ball joint wear out super fast. I've seen images of a tie rod end being extracted from the steering knuckle and the ball joint stud simply flops around.. these ball joint and rod end like end links need to be tight or taunt.

 

[mfgenggear]

Well my thoughts are, inadequate meturgy and stiffness of the components. Seems the bean counters cutting cost. Maybe moment is causing yielding of the components.

 

[BrianPetersen]

The common feature between Jeep Wranglers and Land-rovers of the type mentioned in the original post (along with a few others known for similar behaviour) is the solid front axle. A disruption on one side affects the other side. Sloppiness in anything affects both sides.

I'm not aware of decent independent suspension designs getting into positive-feedback steering situations. Yes, they can have "vibration" due to a wheel being off balance or a tyre worn unevenly and they can be "sloppy" if the bushings are shot, but I've never seen one go into what us motorcyclists would call a "tank-slapper" - a nasty positive-feedback steering oscillation in which something impacts the steering and kicks it (let's say) left, then the restoring-to-center forces kick it even harder to the right, then the restoring-to-center forces kick it even harder to the left, with the steering wheel oscillating hard in ever-increasing magnitude until something in the steering mechanism reaches a mechanical limit that contains it.

I've never owned such a vehicle ... I've been in a couple of them for long enough to hate the way they ride. Every bump gives a sideways ride-motion kick to the whole vehicle, and I can understand why. The front geometric roll centre is significantly above ground level, which means a one-wheel bump pulls the contact patch of both tyres sideways relative to the body as the axle tilts as it goes over the one-wheel bump - which in reality means the body is getting a sideways kick in addition to the bump motion. I've seen quite a number of lift-kit-equipped 4x4 vehicles in which the front track-rod and steering arm are significantly angled downward from the vicinity of the steering box (chassis end) to the axle end, which means in addition to the inherent sideways kick from the roll centre being up high, there's another asymmetrical sideways kick from the track-rod actually physically moving the axle sideways relative to the body and doing so differently when going over a one-wheel bump on the right side compared to a one-wheel bump on the left side. Evidently the people who drive such vehicles, don't seem to care. It won't be me ...