Death wobble!?

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wammers said:
Neither does fitting poxy polly bushes instead of proper ones. Specially in the wrong place.
Click to expand...

:)

Agreed. I can see the appeal though. That Britpart kit costs the same as 2 proper bushes.

From the reviews I saw the poly bushes are all right in certain locations like the anti-rollbar but not all, particularly where articulation is present.
 
Update...
So, got the car back from the workshop. Couldn't have a look underneath yet, but driving has improved. I'll be checking underneath later on. No more death wobble so far (only drove 5 Km highway), but still there's a vibration. I would say the remaining of the vibration is down to steering damper, drag link, swivel rods and brake discs (soon to be replaced).
Not very impressed with the Britpart bush kit so far as it is very hard on rough roads now, but let's give them a fair try once I have all the other parts replaced.
Like I was advised before, it can happen that due to the bushings being new, everything is more stiff now (and I can feel that in the ride comfort) and the other components are struggling to keep everything in place.
More updates once I replace the steering damper over the next few days.
 
Tilo said:
Update...

So, got the car back from the workshop. Couldn't have a look underneath yet, but driving has improved. I'll be checking underneath later on. No more death wobble so far (only drove 5 Km highway), but still there's a vibration. I would say the remaining of the vibration is down to steering damper, drag link, swivel rods and brake discs (soon to be replaced).

Not very impressed with the Britpart bush kit so far as it is very hard on rough roads now, but let's give them a fair try once I have all the other parts replaced.

Like I was advised before, it can happen that due to the bushings being new, everything is more stiff now (and I can feel that in the ride comfort) and the other components are struggling to keep everything in place.

More updates once I replace the steering damper over the next few days.
Click to expand...


They never get much better in my experience, I still have them but just got used to the harsh ride.

I would be surprised if the fitted the bushes the wrong way round, I seem to recall they are different sizes?

Anyway I have experienced what you describe and it was old tyres, balancing helped but new tyres seem to have sorted it. Still occasionally get a bit more movement than I would like but only if I hit a very big hole and I put this down to the stiffness of the bushes.

As said it's more than likely a combination of things highlighted by one thing like bad wheel balance.

Good luck
 
I had a really good heave underneath my car with a pry bar and a torch and as my specialist told me everything is very tight.

Having done a little more research into this, I had a feeling (as mentioned in my other post) it's something to do with resonance.

There was a post on another site in which the guy says that there is an inherent design flaw within the P38 set up whereby a combination of small faults will bring a disruptive resonance zone into the operational speed range of the vehicle.

Usually this is not an issue with the set up as the zone is at a speed/rpm level not usually attained in normal driving.

I think that the combination of my non standard shocks, a new generic steering damper and 140k of wear in the steering box combined to bring the set up within the disruptive resonance zone which is ok until triggered by a bump and bang, off it goes.

This all makes sense as any bush or joint that is loose enough to cause such a violent motion would have sheared or exploded long ago and no one on this or any site has a definitive cure for this

I have ordered a new bilstein steering damper to replace the recently fitted generic one and may be re swap the tyres front to back and hopefully the car will be ok again

This may sound like a load of b*ll*x and please don't be too hard on me for supporting this theory but it does seem like a possible cause of this problem

Will report back after swapping the steering damper, I really do hope I can so this out
 
Last edited:
Update...
New steering damper in place and that made quite a difference. The old one had no action at all! 50 Km done. No death wobble (so far) and very little vibration remaining. Steering is a lot more responsive and a lot less play than before the bushes were fitted and I get to feel every road crack on the steering and the body. Poly bushes no more! very cheap but very uncomfortable. Can't wait for them to worn out.
Now, as I said before, I think the remaining vibration is down to brake discs and, as I was able to check underneath yesterday, the steering track rod, which felt quite loose when I tried to twist it and the rubber on the rods completely ripped off.
More updates over the next weeks when I have tackled these out.
 
Tilo said:
Update...
New steering damper in place and that made quite a difference. The old one had no action at all! 50 Km done. No death wobble (so far) and very little vibration remaining. Steering is a lot more responsive and a lot less play than before the bushes were fitted and I get to feel every road crack on the steering and the body. Poly bushes no more! very cheap but very uncomfortable. Can't wait for them to worn out.
Now, as I said before, I think the remaining vibration is down to brake discs and, as I was able to check underneath yesterday, the steering track rod, which felt quite loose when I tried to twist it and the rubber on the rods completely ripped off.
More updates over the next weeks when I have tackled these out.
Click to expand...

Think if i had a steering wobble i would be checking the steering box, track rod, draglink and steering damper long before i considered new radius arm bushes.
 
wammers said:
Think if i had a steering wobble i would be checking the steering box, track rod, draglink and steering damper long before i considered new radius arm bushes.
Click to expand...

I didn't have a steering wobble, I had no bushes at all! The steering wobble came on after replacing the bushes...
And I'm not saying the bushes are causing the wobble, I'm just giving my opinion that they are too hard and make the ride uncomfortable. That would be the only reason why I would change them for OEM.
 
Tilo said:
I didn't have a steering wobble, I had no bushes at all! The steering wobble came on after replacing the bushes...
And I'm not saying the bushes are causing the wobble, I'm just giving my opinion that they are too hard and make the ride uncomfortable. That would be the only reason why I would change them for OEM.
Click to expand...

Even if you replace with new genuine bushes the suspension will tighten up and seem more taught. The suspension rides on air springs new bushes don't make those any harder. New bushes just tighten the torsional movement of the axle. Making the front axle harder to twist in particular.
 
Have a read of this, put far more succinctly than I

"I had the same problem years ago on my 98SE.

Freeway speed, drive over some uneven section of road and violent shakes, scary, dangerous and embarrassing.
I would describe it as tank slapping, (a motorcycling term for a similar scary thing that happens to riders from time to time)
I changed the suspect steering damper first up, as it was on the way out, but like you, still had the problem, as bad or worse.

After reading the numerous posts here and considering all the different things others have tried, I can only come to one conclusion:

The inherent design of our truck's front end is such that, with a particular combination of wheels, tyres, toe in, shock absorbers, and steering box adjustments, there is a natural resonance , which at a certain critical speed the front end can be set off like a bell ringing. Set off by a disturbance, a bump.
Once it starts, it just self excites and keeps going, until you get away from that critical speed.
You can be fortunate, in that for your car, the critical speed for resonance is so high you never reach it.
Others are not so lucky.
Changing components can change the resonant point so much, that it no longer is an issue, or if the components you change have basically the same characteristics, the problem remains.

As with all resonance circuits, a good damper can kill the vibrations or prevent them from starting up.
Some cars will have the problem worse than others of course, and then even a good damper may not help.
All of the above is just my theory of course!

Did you change the steering damper with a genuine one or an aftermarket one?

Why I ask is because after a lot of checks, similar to what you had done, for some mysterious reason, I decided to pull out the new damper and check it on the bench.
It was an aftermarket one, from the UK, (I am in Australia).

The damping was good and firm in both directions but when I applied small back and forth movements rapidly, there was a small amount of movement possible which was not damped at all. About 10mm to 15mm.

That was enough for me. I bit the bullet and purchased a genuine article, at about twice the price.
That was one of the best decisions I have ever made,.
After installing it, no more violent shakes, ever!

I know that it does not fix the underlying cause, but bear witness to the many who have effectively had to change the whole front end to get a result.

My problem may have been different to yours of course, but, I have done over 100,000k now since fitting the new genuine steering damper, and no more death wobbles, even once.

Good luck and cheers".
 
wammers said:
Even if you replace with new genuine bushes the suspension will tighten up and seem more taught. The suspension rides on air springs new bushes don't make those any harder. New bushes just tighten the torsional movement of the axle. Making the front axle harder to twist in particular.
Click to expand...

Mine is on steel springs...
 
AP90 said:
Have a read of this, put far more succinctly than I

"I had the same problem years ago on my 98SE.

Freeway speed, drive over some uneven section of road and violent shakes, scary, dangerous and embarrassing.
I would describe it as tank slapping, (a motorcycling term for a similar scary thing that happens to riders from time to time)
I changed the suspect steering damper first up, as it was on the way out, but like you, still had the problem, as bad or worse.

After reading the numerous posts here and considering all the different things others have tried, I can only come to one conclusion:

The inherent design of our truck's front end is such that, with a particular combination of wheels, tyres, toe in, shock absorbers, and steering box adjustments, there is a natural resonance , which at a certain critical speed the front end can be set off like a bell ringing. Set off by a disturbance, a bump.
Once it starts, it just self excites and keeps going, until you get away from that critical speed.
You can be fortunate, in that for your car, the critical speed for resonance is so high you never reach it.
Others are not so lucky.
Changing components can change the resonant point so much, that it no longer is an issue, or if the components you change have basically the same characteristics, the problem remains.

As with all resonance circuits, a good damper can kill the vibrations or prevent them from starting up.
Some cars will have the problem worse than others of course, and then even a good damper may not help.
All of the above is just my theory of course!

Did you change the steering damper with a genuine one or an aftermarket one?

Why I ask is because after a lot of checks, similar to what you had done, for some mysterious reason, I decided to pull out the new damper and check it on the bench.
It was an aftermarket one, from the UK, (I am in Australia).

The damping was good and firm in both directions but when I applied small back and forth movements rapidly, there was a small amount of movement possible which was not damped at all. About 10mm to 15mm.

That was enough for me. I bit the bullet and purchased a genuine article, at about twice the price.
That was one of the best decisions I have ever made,.
After installing it, no more violent shakes, ever!

I know that it does not fix the underlying cause, but bear witness to the many who have effectively had to change the whole front end to get a result.

My problem may have been different to yours of course, but, I have done over 100,000k now since fitting the new genuine steering damper, and no more death wobbles, even once.

Good luck and cheers".
Click to expand...

It fits. Worked for me as well (so far...).
The only strange fact for me is: how was it possible to be driving with no rubber left on the bushes and everything was well, not even a slight vibration? And, how did the new bushes caused the wobble to appear?
 
Tilo said:
It fits. Worked for me as well (so far...).
The only strange fact for me is: how was it possible to be driving with no rubber left on the bushes and everything was well, not even a slight vibration? And, how did the new bushes caused the wobble to appear?
Click to expand...

Well if the resonance theory is true, then prior to you replacing the bushes, the axle was 'grounded' as it were, once in suspension with new bushes, this allowed the resonance to escalate, if that makes sense.

Just fitted the new bilstein damper, will field test tomorrow, the old generic one did have a little play in it, so I'll see what happens, so pleased if this is the fix
 
This is a known Rangie issue and is caused by one of either three things:

1: worn bushes on the panhard rod. Often the right hand one as steering oil drops on it and rots out the inside. Looks fine on the outside but shot in the other side.

2: less common, the steering damper is kaput. Look for oil leaks but really just drop it off at one end and push it in looking for flat spots caused by air etc.

3: the more time consuming one, you've got play in your swivel pins and you need to remove a shim to tighten the ball joint back up.

The latter may show itself as a tiny amount of play when lifting a wheel up and down.

If you have that classic Rangie full in wibble triggered by a bump these are the three things that cause it and they are dirt cheap to fix.

Play in or buckled track rods would be a constant wobble as would other loose bearings or unbalanced wheel etc. The body wibble is triggered by a loss of damping in the steering.

A new Panhard is £20, a new damper isn't much more and a shin kit is less. And they can all be tested and fixed on a driveway.

It's a very well known problem and any Rangie mechanic will know of it and exactly know the fix
 
Horse_Apple said:
This is a known Rangie issue and is caused by one of either three things:

1: worn bushes on the panhard rod. Often the right hand one as steering oil drops on it and rots out the inside. Looks fine on the outside but shot in the other side.

2: less common, the steering damper is kaput. Look for oil leaks but really just drop it off at one end and push it in looking for flat spots caused by air etc.

3: the more time consuming one, you've got play in your swivel pins and you need to remove a shim to tighten the ball joint back up.

The latter may show itself as a tiny amount of play when lifting a wheel up and down.

If you have that classic Rangie full in wibble triggered by a bump these are the three things that cause it and they are dirt cheap to fix.

Play in or buckled track rods would be a constant wobble as would other loose bearings or unbalanced wheel etc. The body wibble is triggered by a loss of damping in the steering.

A new Panhard is £20, a new damper isn't much more and a shin kit is less. And they can all be tested and fixed on a driveway.

It's a very well known problem and any Rangie mechanic will know of it and exactly know the fix
Click to expand...

Very well known problem on poorly maintained Classics and Discos but not generally on the P38.
 
So with the new Bilstein damper fitted did a hefty run on the M25 and hit many bumps and ruts that would usually send the car into the shuddering fit but nothing

Still have the wobbling passenger seat at 62mph but guess I'll just have to live with that

So pleased to have sorted this problem
 
wammers said:
Very well known problem on poorly maintained Classics and Discos but not generally on the P38.
Click to expand...

Still a ladder chassis with a panhard, a steering damper and swivel pins.

Death wobble is a classic symptom that any Rangie mechanic would know about.

Especially seeing as most P38s have been poorly maintained at some point in their long life. ;)
 
AP90 said:
So with the new Bilstein damper fitted did a hefty run on the M25 and hit many bumps and ruts that would usually send the car into the shuddering fit but nothing

Still have the wobbling passenger seat at 62mph but guess I'll just have to live with that

So pleased to have sorted this problem
Click to expand...

this vibration in the passenger seat at about the same speed was my front prop ujs
 
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