Is this normal or first sign of trouble to come?(suspension)

Skeith · Post by **Skeith** » 14 Oct 2005, 17:01

Is this normal or first sign of trouble to come?
When I do full lock with steering wheel mt front suspension rises.

Xantia 97 1.8i 16V 77,000Miles

mezuk04 · Post by **mezuk04** » 14 Oct 2005, 17:34

Have you just purchased the car or had it a while??? does it go back down when you come out of full lock????

Skeith · Post by **Skeith** » 14 Oct 2005, 18:07

I have had the car now for about 2 weeks. while driving it is normal and very smooth. it is just when parking or getting out of parking spaces that I notice this rise. As soon as I move off it is back to normal.

Skeith · Post by **Skeith** » 14 Oct 2005, 18:08

should have mentioned that I have just done the front right and left spheres last sunday. did not do the centre sphere. I dont know how to tell if it is gone.

AndersDK · Post by **AndersDK** » 14 Oct 2005, 18:47

a '97 Xantia would have independent hydraulic pressure source for power steering and suspension.
The pump has outlets for each purpose.

I believe it is a mechanical problem in the front suspension linkage. The height controller (HC) is linked to the antiroll bar (ARB) by a short plastic rod and some mechanical bits. If this gets mucked up & rusty you get all kinds of strange height corrections.

Have you done the Citaerobics lately ?

Post by **RichardW** » 14 Oct 2005, 19:50

Yep, it's normal on the Xantia 8)

There must be something to do with camber / castor set up on the front that means on full lock the suspension corrects the height - a good sign that the front height corrector is working OK

p20 · Post by **p20** » 14 Oct 2005, 21:44

Mine lifts the front end on full lock. If you've used full lock to get into a car park space, then left it for a bit, when you get back, you may find it drops rather quickly, when you start up. Mine sometimes groans whilst doing this. Nearly s'$t myself the first time it did it.

Mandrake · Post by **Mandrake** » 14 Oct 2005, 22:49

RichardW wrote:Yep, it's normal on the Xantia 8)

There must be something to do with camber / castor set up on the front that means on full lock the suspension corrects the height - a good sign that the front height corrector is working OK

It's not the caster or camber, I think the reason is the way the roll bar is connected to the struts - when you turn the steering on full lock the location of the top rollbar balljoint travels around the strut further away from the straight ahead position, thus pulling the rollbar up slightly, making the height corrector think the height is too low, so it lifts slightly.

Yet another side effect of the poor suspension geometry in the Xantia.

Anybody know why they couldn't have just connected the rollbar to the lower control arm as some other cars do ? Would have prevented this problem and also eliminated a balljoint on each side.

Regards,
Simon

Mandrake · Post by **Mandrake** » 14 Oct 2005, 23:00

AndersDK wrote: I believe it is a mechanical problem in the front suspension linkage. The height controller (HC) is linked to the antiroll bar (ARB) by a short plastic rod and some mechanical bits. If this gets mucked up & rusty you get all kinds of strange height corrections.

Indeed. Mine currently has about 10mm of overshoot in the height correction at the front, when going up it stops at a point about 5mm too high, but when travelling down it stops at a point about 5mm too low. Also how much too far it goes is semi-random.

On the other hand my Dad's car always stops at the same height correcting up, and when it corrects down it moves quickly enough that it goes about 5mm too far, but then unlike mine, it then creeps back up 5mm again and stops at the same height within about a millimetre.

While I had the rollbar clamp loosened to adjust the height, I've found the reason for this overshoot - the combination of the spring/arm assembly and/or the height corrector itself has more friction than the self centering spring strength in the height corrector.

If while the rollbar clamp was loose I pushed the linkage slightly one way to make the car go up or down, when I release it, it KEEPS GOING, and doesn't stop until I push a little bit the other way.

When the tension on the rollbar clamp input is removed the height corrector should centre and stop immediately. So the overshoot is caused by the height corrector not closing when the plastic linkage becomes slack - the height has to go a bit too far to cause the slack in the linkage to be taken up in the opposite direction before the height corrector is closed.

My guess is a bit of extra drag in the arms that the spring is hooked onto. I'm considering disconnecting the height corrector and lifting out the whole bracket that the height corrector is bolted onto to have a look at and lubricate of it on the workbench. Is that practical ? (It's sure difficult to get at in place....)

Regards,
Simon

Kowalski · Post by **Kowalski** » 14 Oct 2005, 23:09

Mandrake wrote: Anybody know why they couldn't have just connected the rollbar to the lower control arm as some other cars do ? Would have prevented this problem and also eliminated a balljoint on each side.

The suspension on a Xantia has no inherent anti-roll that a steel sprung car would have, so all of the anti-roll is done by the anti-roll bar. The anti-roll bar has to be rather stiff to cope. What the Citroen engineers have done is design the geometry so that it PRE-LOADS the anti-roll bar when you turn the steering, giving a greater anti-roll effect. The anti-roll bar does not need to be as stiff as it would otherwise have been and it makes the steering feel that bit sharper.

So, if you want rid of the balljoints, you'd have to put up with either stiffer suspension / harsher ride or more body roll.

Mandrake · Post by **Mandrake** » 14 Oct 2005, 23:29

Kowalski wrote:
Mandrake wrote: Anybody know why they couldn't have just connected the rollbar to the lower control arm as some other cars do ? Would have prevented this problem and also eliminated a balljoint on each side.
The suspension on a Xantia has no inherent anti-roll that a steel sprung car would have, so all of the anti-roll is done by the anti-roll bar. The anti-roll bar has to be rather stiff to cope. What the Citroen engineers have done is design the geometry so that it PRE-LOADS the anti-roll bar when you turn the steering, giving a greater anti-roll effect. The anti-roll bar does not need to be as stiff as it would otherwise have been and it makes the steering feel that bit sharper.

So, if you want rid of the balljoints, you'd have to put up with either stiffer suspension / harsher ride or more body roll.

How do you figure that it preloads the rollbar ? I don't see that. If turning the steering to either lock causes the height corrector to make a height increase, this means that there is a change in the position of the rollbar ends in the SAME DIRECTION at both ends, eg the rollbar is rotating rather than twisting, since the height corrector is clamped in the middle of the bar and doesn't response to rollbar twist.

If the rollbar droplink top balljoint is centrally aligned relative to the angle of the bar (can't remember if thats the case or not) then turning the steering to either side will pull on the rollbar end, turning the rollbar slightly, but not preloading it.

I would also point out that all earlier Citroen's with proper wishbone arms connect the rollbar to one of the control arms (Usually the upper load bearing one) and don't have spurious height corrector responses to the steering being turned.

I actually think that a lot of the roll reduction on Xantia's compared to older models such as GS and CX is actually more to do with partial strut binding under sideways (cornering) thrust preventing small/slow movements in much the same way as heavy damping. Immediately after greasing the front struts I notice that my Xantia (which is HA2) rolls a LOT more than it does after a few days when the initial improvement has faded away.

Then there is the fact that the rollbar droplinks pull at an angle to the strut alignment so that the rollbar itself will introduce some side thrust on the strut during cornering...

I really can't see how you can defend the front suspension design of the Xantia, it really is a cheap compromise (with numerous geometry "issues") compared to earlier models with proper wishbones, and out of all the things on the Xantia the McPherson struts are by far and away the biggest dissapointment to me as someone who has owned and driven older Citroen's....

Citroen have made great strides in the hydraulic systems since earlier models (anti-sink, Hydractive 2, Activa etc) and yet have retrogressed in the basic mechanical aspects, such as geometry, ruggedness, longevity etc.

Apart from spheres and maybe the odd balljoint, a GS suspension would last 20 years without any serious problems, easy. I've never heard of the rollbar droplinks needing replacing on a GS. Mine was over 20 years old when I sold it (after having it for about 7 years) and there were no mechanical problems with the suspension at all. (The body rust was another matter though

) More to the point, the ride when the spheres were regassed was as good as new.

Compare that to a Xantia where everyone shrugs their shoulders when droplinks wear out after 50,000km, or where an 8 year old car (like mine) could have had serious strut top rubber mount failure. How many strut tops will a Xantia get through by the time it's 20 ? How will the struts themselves be at 20 ? Will it still be riding well at 20 with just spheres replaced, or will it need the struts replacing to get back the as-new ride quality ? (I'm betting yes, if the BX is anything to go by)

Regards,
Simon

Kowalski · Post by **Kowalski** » 15 Oct 2005, 00:18

Mandrake wrote: How do you figure that it preloads the rollbar ? I don't see that. If turning the steering to either lock causes the height corrector to make a height increase, this means that there is a change in the position of the rollbar ends in the SAME DIRECTION at both ends, eg the rollbar is rotating rather than twisting, since the height corrector is clamped in the middle of the bar and doesn't response to rollbar twist.

The key to it is that the drop links and struts don't run parallel. The drop link connects to the side of the strut, when you turn to the strut, the top of the drop link is either pulled forwards or backward, this either increases or decreases the angle between it and the strut, effectively "shortening" or "lengthening" the drop link and applying a pre-load to the anti roll bar.

Again, because of this triangular geometry and the lengthening effect, the two ends are not lengthened by the same amount, so when you put full lock on, it twists the anti-roll bar and your height corrector tries to correct it.

Its not a perfect system by any stretch of the imagination, it can't for example alter the amount of pre-load dependent on speed, e.g. a small steering input at high speed will produce more roll than the same input at a lower speed, and it does have the side effect mentioned above. There isn't an equivilent system at the rear end either.

I actually think that a lot of the roll reduction on Xantia's compared to older models such as GS and CX is actually more to do with partial strut binding under sideways (cornering) thrust preventing small/slow movements in much the same way as heavy damping.

Much thicker anti-roll bars and stiffer suspension have more to do with it than struts binding. I've got two Xantias with full magic carpet ride and while they do take a little while to get full body roll (due to damping), it doesn't get any worse when you go over bumps, neither of my Xantias have sticky struts or hydractive.

I'd agree with you that Macpherson struts are for cheapness, but the pre-load on the front arb is a nice feature that you won't see on a double wishbone setup. PSA have put double wishbones on the 407 and C6, perhaps the C5's replacement will have them too (although the way Citroen is heading it will probably be a 408 or whatever with a Citroen badge).

Skeith · Post by **Skeith** » 17 Oct 2005, 01:48

So it happens to many people so it may be normal with xantias.
Citaerobics > now i'm intrigued. must do a forum search.

EDIT: found it ..

LOL @ "Never do this while driving the car !"

AndersDK · Post by **AndersDK** » 17 Oct 2005, 23:55

The BX had the simple setup with droplinks directly connecting the ARB to the lower triangle control arm.
AFAIR the BX ARB's are rather heavy compared to the weight of the BX - because of this setup.