Death wobble!?

Tilo said:

Well folks, I'm at the point of :crazy::boom:

Like I said, yesterday, after replacing the front brakes and the track rod went for a quick drive just to make sure everything was ok and I could feel the vibration coming in at around 100 kph.

So this morning, got in the car for a 50 Km drive to work, mostly highway.
Here's what's happening...

The vibration seems to randomly appear but always at 100"ish" kph speeds. If I go over or slow down, it stops and everything is smooth.
Now, I might be going crazy but I would swear it comes in between curves... I mean, after each curve and coming to a straight sometimes the car would vibrate and sometimes not.

One other thing I've noticed was that if the curve was long enough, the vibration would come for a few seconds and then go away while on the same turn.

Could it be a bad wheel balancing and the vibration being triggered by different wheel speeds to a particular combination of the wheel position where they get imbalanced!? Flat spots? Bent rims?

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As has been said earlier, a defective tyre will cause that.

Datatek said:

As has been said earlier, a defective tyre will cause that.

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Then, why isn't the vibration constant? Why it comes and goes?

wammers said:

Do they fit snugly on the hub? The L322 has a larger hub boss so the wheels have a larger centre diameter. That is what you need to be measuring. IF you have any L322 wheels fitted without spigot rings the wheels will not be central about their axis. Running like that will cause what you have. Worth checking.

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Ok thanks will check that out

Tilo said:

Then, why isn't the vibration constant? Why it comes and goes?

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Same reason an out of balance tyre tends to show at certain speeds.

Datatek said:

Same reason an out of balance tyre tends to show at certain speeds.

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Before driving back home, inflated the tires with 3.0 bar, just to see what would happen.
Couldn't drive it more than 85 without the wobble kicking in!
Going for the wheel balancing again tomorrow.

Datatek said:

Same reason an out of balance tyre tends to show at certain speeds.

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If you have slightly out of balance wheels on a P38 you can bet they show at 50 to 55 MPH. Will usually go away after harmonic response phase of axle above 55 MPH.

Tilo said:

Before driving back home, inflated the tires with 3.0 bar, just to see what would happen.
Couldn't drive it more than 85 without the wobble kicking in!
Going for the wheel balancing again tomorrow.

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Either your tyres are deformed, badly out of balance or both. They need to be both statically and dynamically balanced.

I think you posted that you had done the u/j's but.......... worth rechecking?

Yesterday I had the wheel balancing done again but there's not much improvement...
I guess I'll have to live with it until I replace the tires.
The violent wobble is gone but, occasionally, I get the body vibration and the Vibroplate passenger seat between 90 and 100 kph.
I checked the prop shafts and both look quite bad: rusty, dirty and dry. I couldn't lubricate them as the nipples are blocked and the grease wouldn't go in. So, I might get those replaced as well.
That's it for me (for now...).

Thanks all for your help and suggestions.

Cheers and I hope others can fix their issues

Tilo said:

Yesterday I had the wheel balancing done again but there's not much improvement...
I guess I'll have to live with it until I replace the tires.
The violent wobble is gone but, occasionally, I get the body vibration and the Vibroplate passenger seat between 90 and 100 kph.
I checked the prop shafts and both look quite bad: rusty, dirty and dry. I couldn't lubricate them as the nipples are blocked and the grease wouldn't go in. So, I might get those replaced as well.
That's it for me (for now...).

Thanks all for your help and suggestions.

Cheers and I hope others can fix their issues

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Try putting new nipples in.

Tilo said:

Yesterday I had the wheel balancing done again but there's not much improvement...
I guess I'll have to live with it until I replace the tires.
The violent wobble is gone but, occasionally, I get the body vibration and the Vibroplate passenger seat between 90 and 100 kph.
I checked the prop shafts and both look quite bad: rusty, dirty and dry. I couldn't lubricate them as the nipples are blocked and the grease wouldn't go in. So, I might get those replaced as well.
That's it for me (for now...).

Thanks all for your help and suggestions.

Cheers and I hope others can fix their issues

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UJ's rusty I'd replace them PDQ before one lets go and smashes your gearbox.

I agree with Datatek

If your UJ's are rusty, it's too late to grease them - replace them

I have just done the London to Cornwall run in mine and the violent shuddering is now cured.

The fitting of a quality Bilstiein steering damper has sorted it, but all bushes and steering links at the front are new as well so I think it all adds up.

I replaced all my prop UJ's in an attempt to cure the wobbly seat issue, bit of a waste of time as all mine were in good nick, but as other guys have said do change yours if they are rusty. also check the condition of the sliding action on the shaft too, but do make some reference marks before disassembling

So pleased to have sorted the scare shudder at long last

I'm not sure if they're that bad...
I tried to turn them by hand and the rear propshaft doesn't move at all. The front propshaft has a little tiny play.
Is that enough reason to get it replaced?

AP90 said:

I have just done the London to Cornwall run in mine and the violent shuddering is now cured.

The fitting of a quality Bilstiein steering damper has sorted it, but all bushes and steering links at the front are new as well so I think it all adds up.

I replaced all my prop UJ's in an attempt to cure the wobbly seat issue, bit of a waste of time as all mine were in good nick, but as other guys have said do change yours if they are rusty. also check the condition of the sliding action on the shaft too, but do make some reference marks before disassembling

So pleased to have sorted the scare shudder at long last

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Glad to hear!

Tilo said:

I'm not sure if they're that bad...
I tried to turn them by hand and the rear propshaft doesn't move at all. The front propshaft has a little tiny play.
Is that enough reason to get it replaced?

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You need to lift a wheel off the floor to check for play in the prop shafts. One front wheel to check front prop and one rear wheel to check rear prop. Make sure you chock the other rear wheel whilst checking the rear one or you may end up with tyre marks across your chest.

Tilo said:

I'm not sure if they're that bad...
I tried to turn them by hand and the rear propshaft doesn't move at all. The front propshaft has a little tiny play.
Is that enough reason to get it replaced?

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If they are rusty and you can't get grease in them they are most likely fecked, but it's your choice. When they break it can be catastrophic

wammers said:

You need to lift a wheel off the floor to check for play in the prop shafts. One front wheel to check front prop and one rear wheel to check rear prop. Make sure you chock the other rear wheel whilst checking the rear one or you may end up with tyre marks across your chest.

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Lift one wheel and put it on D or just turn it by hand?

Tilo said:

Lift one wheel and put it on D or just turn it by hand?

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You have to lift a wheel on each axle to take the weight off the prop shafts. For instance the rear wheels are holding the car on the hand brake you will never get any joint movement with the weight of the car on the rear axle. Lift a wheel and hold the U/Js and get someone to rock the lifted wheel. You will feel play long before you can see any.

I apologize to have pulled this thread from the ashes but...

This is turning into a bit of a quest... and a money well.

Propshafts in place. Little improvement, yet, not fixed, only less violent.

One thing I've noticed, there's a humming noise and a slight vibration can be felt in the footwell (LHD) at about 90 Km/h once I take my foot off the throttle. As soon as I accelerate again it goes away. Any ideas? (Could it be related to the shock noise I describe below?)

Don't know if it's relevant or not, but on tight turns at low speed (5-10 Km/h), p.e. accessing parking or maneuvering, you can feel a little roughness all over the car. Again, only when the steering wheel is almost fully turned to either side.

So far:
1. all suspension bushes replaced (front and rear) with Britpart polybush kit DC7107 (they might be crap, but can't do anything about it now...)
2. steering shock replaced (aftermarket, did it myself)
2. wheels balanced (probably poorly balanced)
3. Front brake pads and discs replaced (done by me, so nothing could go wrong here ound
4. wheels balanced (again and again probably poorly, can't trust anyone on this. I might try to go and learn how to do it myself and get someone to let me use the machine)
5. front and rear propshafts replaced (I tried to do it, but couldn't remove the nuts so sent it to the workshop)
6. whats next? Swivel ball joints? Put another set of wheels and see if it makes a difference?

I'm determined to get to the end of this now...

Also, last week I started to hear a knocking noise from the front left side and you can even feel in your feet (LHD) when going over a hump with a bit more speed. It doesn't come when accelerating or braking hard, so I figure it's related to up and down movement. Crawled underneath and it seems to me the front left shock is not tight enough. It turns very easily by hand, whereas the left side it's very hard to turn. Also there seems to be a small gap between the lower bush and the mounting plate. Is it worth to look into it? How do I stop the shock absorber from turning while tightening the nut?