Xantia front rises on full lock

[Stewart(oily)]

Hi all, I am sure I have encountered this in the past, the front end of my 99 Xantia rises when the car is on full lock,it drops slowly back to normal once straightened up and behaves normally when doing citaerobics, I lubricate height correctors every year though it is due some fresh LHM .

[GiveMeABreak]

I think all my hydro Citroens have done this, extra clearance for the wheel arch.

[CitroJim]

It's completely normal...

[MikeT]

Even my C5 does it.

[Mandrake]

I think all my hydro Citroens have done this, extra clearance for the wheel arch.

Not all Hydro Citroen's do it, only some of those with McPherson struts like Xantia, XM and C5.

GS, DS and CX with double wishbones never did this, and I believe the BX doesn't do it either. (I've never driven a BX)

It's not on purpose either, its a side effect of a geometry error caused by the way the roll bar is attached directly to the side of the hydraulic ram/strut.

If you watch closely you'll see that when you turn the steering the main body of the ram turns with it, as does the "loop" on the side of the ram that the drop-link bolts to. Whether you turn the wheel left or right you are pulling the top of the drop-link "away" from the roll bar at an angle, (it is no longer vertical as it is when the steering is straight ahead) this causes the roll bar to rotate in the same direction it would if the suspension height was too low - the height corrector, measuring only roll bar rotation, sees this "error" in the roll bar orientation, assumes the height is too low and lifts the car up a bit to compensate. When you straighten up it corrects the other way.

GS/DS/CX don't suffer from this problem because the roll bar attaches to the upper wishbone arm and thus is not affected by steering. I believe on the BX despite being a McPherson strut design the roll bar attaches to the lower arm instead of to the strut - if this is true, it also won't be affected by this problem as the lower arm will not move when steering...

[GiveMeABreak]

I'm sure the X7 does it occasionally and that has a double wishbone setup without Mcpherson struts.

[Stickyfinger]

I'm sure the X7 does it occasionally and that has a double wishbone setup without Mcpherson struts.

Mine does, but as much as the Mk1/2's did.

My Activa does not however......not that I have noticed anyway (will try that tomorrow)

[Mandrake]

I'm sure the X7 does it occasionally and that has a double wishbone setup without Mcpherson struts.

Where and how are the height sensors connected ?

[Stickyfinger]

roll bars

[GiveMeABreak]

On the Roll bars for the 4 cylinder and on each wheel for the 6 Cylinder Models, as here:

6 Cylinder Front

6 Cyl Rear

4 Cylinder Front

4 Cyl Rear

[Stewart(oily)]

Thank you all for the replies, you would think that after the last 11 years in Xantias, and even more in BXs previous to that you would think that I might have noticed

[Xantippa]

On later C5 X7 4-cylinder models there is one height sensor front and two on the rear axle - at least on HDi180 model.

[GiveMeABreak]

Show me please - that's not documented anywhere that I can see. Only ever one on the rear and one of the front for 4 Cyl models in the docs.

Found it - though not obvious there is a right and left one mentioned - so we can now add this to the above!
It shows a left and right sensor but just one pickup, so wondering if this unit combines the 2 or there are 2 of these as well?

Very interesting as to why they decided to make that change so late in the day..... well spotted Xantippa.

[Stickyfinger]

Two as backup...... when one of them rusts and falls off ?

I wonder why they added one, as you say, so late in the production run ?

Question, on the V6 cars, do the struts/height act independently of each other ?

[GiveMeABreak]

No they just send all their values into the CSS suspension unit which is different to the 4 Cyl one. This CSS ECU was the same as the C6 Unit, but without the AMVAR independent damping control features.

It uses different software and performs different calculations to account for the 4 sensor inputs along with all the other sensors to perform the height corrections.

Not sure why, but maybe with the extra power/ speed and weight of the 6 Cyl they need to have this setup.