[davevet]

Now i know the "Death Wobble" topic has been discussed many many times... and sounds like thats usually kingpins.....

There seems to be a lack of distinction between those looking for solutions to wheel death wobble... and the other sort of death wobble... I am assuming there is another name for it...

So anyway, long and sort is the first time I took 3 passengers and luggage offroading... driving down the highway anywhere from 40/100kmh when I would hit a bump or come into some wind, or i could start it by a quick steering flick.... but the car will rock back and forth.... it isn't crazy like the car is going to flip... but people like to stare lol and its not fun...

Now the problem happens most of the time even driving my myself...

When i rock the car from outside while stationary ... i can see the wheel moving .... so does this mean when the car rocks the steering slop is what is causing it to oscillate?



Sorry for the confusing description! thanks

[atari4x4]

Skateboard syndrome.

[davevet]

haha really? when you think about it.... kinda what its like....

[pete_79]

So he needs to tighten his trucks then???

[jdk81]

This can be a pain, and very dangerous.
It is possibly the dampers (shock absorbers), but this would be evident all the time with dangerous bouncing and the car snaking around (but im not 100% sure of your accurate description).

I'm pretty sure it is due to the extra weight.
Meaning springs are compressed more, and load leaves come into play. (Depending on weight of loads and mods, you may be over gvm)
This effectively means the spring rate has increased, and mass has increased.
Dynamic equations means the natural frequency has now changed and the whole system is underdamped.

The dampers might be correct when the car is at normal weight, but dangerous when heavy or overloaded.
The issue is design compromises need to be made, manufacturers choose between comfort, payload and price.
you can run a commodore/hiace shock combo and itll be fine, however when you take the weight out the car will suck so much.

As per wheel moving by car rocking.
as the nose of the car moves over the springs, the steering wheel moves.
Another aspect makes it all worse is due to the design in leaf spring setup in suzukis, as the car rocks the wheel base on the lower side of car extends, causing more weight shift and more extension on wheel base, this too also moves the steering wheel.
Meaning when a sierra starts to snake, the dynamics of it feeds back into itself and gets worse and worse, you need to gently lose speed and counter the sway with steering control.

Its these things in a correctly setup and maintained car which means the driver is always chasing the wheel and constantly adjusting it, as it all changes so much during normal driving.
When there is a mechanical or human problem its a lot worse.
the two worse aspects of leaf springs.

[tanshi]

yep sounds like crazy worn out suspension to me.

[Gwagensteve]

Three passengers and luggage means the cars centre of gravity has gone way up, accentuating body roll caused by steering input. It's also way increasing the inertia of the car.

I vote trashed shocks, also possibly very worn shackle bushes, and potentially heavily worn shackles.

As an aside, my guess is that the car will have been overloaded by a fair margin with four people and gear in it, so even with everything in good condition it won't handle very well.

The steering wheel rocking as you rock the car is normal.

[bangn]

sounds like you need to spend some coin on suspension

with my old 300K old suspension the car used to almost change lanes from a breath of wind. Now it drives straight since replacing everything.
Your shackles are most likely pivoting from worn bushes/springs and letting the diff and springs shimmy side to side.

of course there are a lot of reasons these things shimmy.

Tyre pressures
Wheel Bearing Play
King Pin Bearing Play
Diff angle changed from a spring lift requiring wedges
Bushes cactus
Play in the ball joints
Play in the steering box or rag joint.
Rim offset/wheel spacers

I know in instances you can have all this correct and still have to fine tune with tyre pressures and caster angle correction wedges to get a happy balance.

[davevet]

Thanks for your input guys,

The weight wasn't 'extreme' just me 80kg and two girls 45ish and luggage just an eski (almost empty) and some sleeping bags and a tent. Everything stored as low as possible...

Usually you can determine the condition of shocks by the old rock test right? they seem fine to me...

I did notice today... it kind of looks like the front springs are... quite flat.... to a point where i am pretty sure they have a little recurve to them lol :S I'll take a pic...

bangn - yeah she has ~300000 on her - what did you replace?

Also a hell of alot of steering slop but apparently that is normal, by the way it feels if it had less slop it wouldn't wobble ... but maybe thats just how it feels...I adjusted it but its already wound in as much as it can go...

Not often i carry passengers actually,

stock as a rock apart from larger prof tyres

I'm thinking 2 second hand front springs, new bush kit for all leafs/shackles give it all a check as i'm going and see how that goes...

[Gwagensteve]

Front springs are supposed to be flat. This is not the cause of the problem.

The rock test doesn't work on leaf sprung vehicles due to the internal friction of leaf springs.

What's "a hell of a lot" I think factory service limit is 40mm measured at the steering wheel.

Let's just have a look at how little payload a sierra has.

Stock payload is 450kg, but that's from dry, so minus 40kg for fluids and fuel. = 410.
Do you have a bull bar?
Floor mats?
Bigger battery?
This is all additional weight that's part of the payload.
Even heavier tyres, whilst not payload, have huge effect on handling because of their centrifugal force.
I doubt the girls are 45kg each, but assuming they really were mini ladies, you're at 170kg of flesh.

410-170= 240.

A couple of accessories and your gear and you can see you're at 75% of your GVM without even thinking about it. Cars don't drive that well at 75% of their GVM, especially if they have worn components.

[davevet]

haha - wow.... they really can't hold much at all... :S

Shouldn't be too bad when its just me and the gf and a bit of gear...

So testing the shocks is a case of pull out and just assess the movement of the pistons?

Ill have to check steering slop but it feels like... a fair bit... and I am used to my 76' celica box, like mixing porridge...

Ill check the weight of the girls just for laughs haha

[Marko_SJ]

davevet wrote:

haha - wow.... they really can't hold much at all... :S

Shouldn't be too bad when its just me and the gf and a bit of gear...

So testing the shocks is a case of pull out and just assess the movement of the pistons?

Ill have to check steering slop but it feels like... a fair bit... and I am used to my 76' celica box, like mixing porridge...

Ill check the weight of the girls just for laughs haha

My best is on worn components. The list is large as you can see!