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Suspension question

Tech Talk for Suzuki owners.

Moderators: lay80n, sierrajim

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Suspension question

Post by zookster666 »

I have a bit of a problem with my suspension/steering when turning the steering wheel side to side the body moves about 10-15mm ontop of the diff. It has the Suzuki "s" style extended shackles and a full ruf.

The problem is it causes quite alot of under steer, I have Been thinking that a panhard rod could be asolution to stoping this movement.

Has anyone tried this with leaf springs?
Will it have A big effect on suspension cycle (limit travel)

is there a better solution to fixing this problem
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Post by Zachius »

I don't think a panhard rod will work with leaf springs as the panhard rod presumes that the diff can have (limited) movement from side to side on suspension travel from my understanding.

I would guess the best way to solve this problem is to use normal length shackles (why are you using extended shackles?). If there is a reason you are using them, fix the underlying reason rather than masking it with extended shackles.

Or you could just accept that Sierra's understeer :twisted: :P
95 zook, 31" tyres, f + r lockrite, 6.5 gears, 70l fuel tank, 2" body lift, 2" springs
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Post by zookster666 »

Thats what I was thinking extended shackles are there because of the ruf might have to move the hangers again and use a standard shackle which will limit it's travel am I right?
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Post by Zachius »

Not sure. You either need to find someone who has played around with RUF and extended shackles etc. before and get first hand advice off them or experiment.

I don't have any first hand experience.

Gwagensteve probably has some valid points on Auszookers.
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Post by lay80n »

Zachius wrote:I don't think a panhard rod will work with leaf springs as the panhard rod presumes that the diff can have (limited) movement from side to side on suspension travel from my understanding.

I would guess the best way to solve this problem is to use normal length shackles (why are you using extended shackles?). If there is a reason you are using them, fix the underlying reason rather than masking it with extended shackles.

Or you could just accept that Sierra's understeer :twisted: :P

Pnahard rods can work with leaf springs. Some cars (diahatsu Rocky, some full size 1 tonne yank land pick ups) are fitted like this from factory. The panhard rod will limit your flex to a point, but you can fit the panhard rod for road use, and remove it easily offroad if it proves to limit you flex more than you are happy with. The steering will be much more "dirrect". I ran the factory panhard on my old rocky for ages till front end changed meant it didn't fit anymore. Difference was noticable. The trick to setting it up is to keep it as long as practical and as close to flat at ride height as possible, so that the arc it creates has the least left to right shit during cycling of the suspension. Keep in mind you will also have to ensure that it is parallell and close to the same length as the steering drag link or you will induce bump steer.


Layto....
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Post by Guy »

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Post by zookster666 »

I have some bumpsteer at the moment because of my vit p/s setup I am mainly trying to make onroad driving as nice as possible between wheeling. removing it would be easy when off road if need be I'll have a play with it and post what happen and how if feels.
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Post by Gwagensteve »

I'll add something here.

I don't think we are talking about understeer here. Understeer is a loss of traction of the front tyres before the rear whilst cornering. My comments about correct caster and suspension tuning are ways of reducing understeer and promoting oversteer ( and I still question whether that is desirable)

I think what what you're talking about zookster666 is that slow, loose springy feeling that the steering has - like there's a lot of slop to get out of the steering.

Whilst my car doesn't understeer, it does have the normal springy/loose feel that leaf sierras all seem to have in various degrees.

shackle tightness, bush condition, steering box adjustment are the obvious first lines of attack.

A panhard rod is a major engineering feat - it must run exactly in plane with the drag link or you will be introducing bump steer (which might be worse than what you are trying to cure)

Steve.
[quote="greg"] some say he is a man without happy dreams, or that he sees silver linings on clouds and wonders why they are not platinum... all we know, is he's called the stevie.[/quote]
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Post by V.W.Dave »

I have had this problem a few times. Once it was the bushingsworn out causing the loose steering. The second time one of my leafs were broken/snapped. While sitting still it looked normal but once I started to drive it would sag.

Just a few things to look at.
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Post by lay80n »

Gwagensteve wrote:I'll add something here.

I don't think we are talking about understeer here. Understeer is a loss of traction of the front tyres before the rear whilst cornering. My comments about correct caster and suspension tuning are ways of reducing understeer and promoting oversteer ( and I still question whether that is desirable)

I think what what you're talking about zookster666 is that slow, loose springy feeling that the steering has - like there's a lot of slop to get out of the steering.

Whilst my car doesn't understeer, it does have the normal springy/loose feel that leaf sierras all seem to have in various degrees.

shackle tightness, bush condition, steering box adjustment are the obvious first lines of attack.

A panhard rod is a major engineering feat - it must run exactly in plane with the drag link or you will be introducing bump steer (which might be worse than what you are trying to cure)

Steve.

Inducing oversteering tendancys to a short wheel base vehicle with a relativley high centre of gravity could end in tears :lol:

Layto....
[quote="v840"]Just between me and you, I actually really dig the Megatwon, but if anyone asks, I'm going to shitcan it as much as possible! :D[/quote]
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Post by zookster666 »

Sorry guys I didn't know how to word what is happening what Steve has said is correct it is the vague half a turn of the steering wheel before you turn scenario.

Now I have replaced the spring bushes
The springs aren't new but I only just installed them and are in good condition and the steering box is in good condition. And so are the tie rods

When the steering wheel is turned side to side when stationary the body and chassis moves about 10-15mm before the wheels move (does this make sense?)

I know there is alot of engineering with the panhard rod idea which is not a problem I have the cababilities of doing it I just wasn't sure about using one with leaf springs.

Zookster
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Post by Zachius »

:oops:

As has been said the key to a successful panhard rod would be keeping it as horizontal as possible (to reduce the side to side movement).

And keep it as close to parallel to the steering drag link as possible otherwise when you hit a bump the change in horizontal length of the panhard rod and steering link will differ causing bump steer.

I still reckon this should only be the absolute last resort, as mentioned elsewhere I would attempt using standard shackles first.
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Post by V.W.Dave »

Just a question and something to look at....
Every one has a different idea of what a full RUF is. What exactly do you have? Are your shackles rear mount or front mount? is your chassis extended or do you just have rear springs with longer shackles??

If you have the last one what kind of angle are your shackles on? If they are leaning to far it can cause a light steering wheel as you describe.

Have you take a good look at the nut and pit met arm? and ball joint?

What condition is the steering biscut (rag joint) in?

You said you had replaced all the bushings, Did you have a look at the non replaceable bushing on the spring? If you did look at it was the little tube in it still tight? If it is loose it can cause spring movement.

Are you SPOA ??? If so what kind os steering set up do you have? Shitty Z bars can cause some odd problems.

Just a frew things to look at...
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Post by zookster666 »

For a start I'm not spoa

My ruf is bolted in stock position at rear with shackle mount moved 25mm forward and extended shackles
the bushes are new along with the bolts and crush tubes
the rag joint was eliminated when I fit the p/s it was replaced with another uni joint

As for everything else it's all
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Post by V.W.Dave »

ahhhh ok sorry I missed where you said you had P/S.

I have 2 mates that have the same problem. talk to bluesuzy or suzyblue I can't remember. He has been chaising that problem. I think he put it down to the p/s pump from memmory.
Now I know what your talking about. It feels like you driving a bus that has a lag on the steering.
Is your pump and steering box off the same model and year? If the pump you haver is running a lower pressure or to high of a pressure can cause light steering.

My other mate that had this problem has a zuki pump driving a toyota steering box and he fixed it by fitting a ford pump I think.

If you do have a matching pump and box you need to look at checking the pressure you pump is giving off It may be shot...
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Post by Gwagensteve »

IMHO it's not a pump problem, but it might be associated with the power steering.

Zookster - what PS Box are you running? What pitman arm? Can you take a photo of the steering angles from the front?

The steeper the drag link angle, the worse the problem will be. I've built few cars with Vitara pitman arms and they seem to suffer this problem more than the stock sierra steering box.

Additionally, as Bluesuzy has pointed out in the past, the Vitara steering box has a slower rate than a sierra box, and that's because the vitara has a longer effective pitman arm due to the idler arm setup and a shorter steering arm on the knuckle.

Steve.
[quote="greg"] some say he is a man without happy dreams, or that he sees silver linings on clouds and wonders why they are not platinum... all we know, is he's called the stevie.[/quote]
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Post by zookster666 »

must be the p/s then it started when I fit it it's a stock vit pump and arm and about 2" of lift in total

I thought the Sierra pitman arm was longer than the the vit one is there a shorter pitman arm I can get for the vit box?

Another question how far does a full ruf move the diff forward ?
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Post by Gwagensteve »

No, you need a longer pitman arm to speed the steering up. THe vitara drop pitman arm from lowrange offroad is 17mm longer than stock. This might be a problem if you are full ruf but haven't moved the steering box forward.

Ruf moves the axle forward 40mm.

Here are two (terrible mobile phone) photos of the lowrange drop arm installed. The car is full RUF, 100mm shackles, OME/Dakar springs. It's sitting a bit high in the photos.

Image

Image

We haven't driven this car yet, but we have one running on another car. The steering is better than a normal vitara PS conversion, but it's not a good an example as the car runs so low that the drag link FALLS from the tie rod to the pitman arm, and the steering box is much further forward than is typical.

Steve.
[quote="greg"] some say he is a man without happy dreams, or that he sees silver linings on clouds and wonders why they are not platinum... all we know, is he's called the stevie.[/quote]
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Post by zookster666 »

Have been out and had a look there is about 15mm between the pitman arm and drag link so that drop pitman arm will definitely foul

if I moved the rear perch back 20mm the axle will still be 20mm further forward than stock am i right?
I'm still currently setting up the suspension in my lwb and have only driven it on road I don't know if the steering arms foul at the moment.

When I fit the vit box I used the stock lower Sierra hole and redrilled the other 2 the box fouls on the front clip and I can't get it any further forward.

Thanks for the help so far very appreciated
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