XM hard rear susspension

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c152slo
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XM hard rear susspension

Post by c152slo »

hi everybody

I am new to this forum, but not new to Citroen magic suspension.

I am having a little problem with my XM series 1. The front susspension
seems very soft and it soak up everything in the road almost without passing it to the cabin. But the rear part is looking very soft when I test it (height corrector worikg OK, spheres OK), but when I drive it, than i does not soak up everything in the road and it gets really hard and noisy. The ride comfort of the back of the car in actualy poor.

And also, when I hit the brake, the rear ends is going extremly up, but I belive, that there is no air in the brakes.

Pums ticks around 20 seconds, so this should not be the problem.

I checked LHM, sphares, hight corrector ... all looks OK.

Could you please give me some advice, what else can I check.

Thank you
Ciaran
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Post by Ciaran »

Bear in mind all XMs are hydractive...

Are you sure the rear spheres are ok ?
Normally the whole car will go hard when HA switches to hard mode, but it is possible to get just the rear doing it.

The fact the hardness is only occurring when the car is in motion, means that one of the many sensors is putting the ECU into hard mode.

Theres no straightforward answer to a HA problem, some general detective work is required unfortunatly.

Have a look here
NiSk
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Post by NiSk »

NO! all XM's are NOT hydractive - especially series 1 models (up to mid 1995)! To check, see if you have a slider switch in the gear lever panel with the "sport/normal" function (hydractive) or not.

Check also that you havn't got the dreaded negative camber sickness (back wheels look like this from a distance /----\ ) caused by worn out rear suspension arm bearings.

Otherwise agree with Ciaren.

//NiSk
Peter.N.
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Post by Peter.N. »

I know this may sound obvious but have you checked the rear tyre pressures? The type of tyre and ammount of tread can also have a marked effect on the ride.
Ciaran
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Post by Ciaran »

NiSk wrote:NO! all XM's are NOT hydractive - especially series 1 models (up to mid 1995)! To check, see if you have a slider switch in the gear lever panel with the "sport/normal" function (hydractive) or not.

Check also that you havn't got the dreaded negative camber sickness (back wheels look like this from a distance /----\ ) caused by worn out rear suspension arm bearings.

Otherwise agree with Ciaren.

//NiSk
Sorry Nisk, I should have said all UK XM's. I became aware recently that some Europaen markets got non-HA cars. A strange concept really !
:)
NiSk
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Post by NiSk »

OK, so all UK XM's had either HA1 or HA2? Didn't know that.
The ride in my '93 XM TD12 (non-HA) is only marginally less comfortable than the ride in my '98 XM TD2.5 Break (HA2) and it has caused me far less grief (and smashed knuckles)!

//NiSk
c152slo
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Post by c152slo »

Hi

Thank you all for your replay.

Of course my XM has HA1. Today we measured all 3 back spheres and they are more than fine. I suspected that the accumulator back sphere is bad, but it is not. We also checked the hight corrector, also working graeat. I also cheched HA connectors they are OK.

Rear suspension arm bearings were replaced 3 years ago, we also checked it today and they are in excelent shape.

But what I later found out is this. When I tested the front and rear part of the car for softnes with and without HA, I did not find out any difference. I am very suprised, because with HA it should be more "hard", should not be?

When I drive the XM, the car is EXTREMLY "gliding" on the road. One Citroen mechanics told me, that this is unbelivable "gliding" for XM with HA, and the XM should not "glide" like that with HA. He told me, that XM without HA is not gliding that well.

Now I am thinking, that may HA does not realy work and the cars behave like the clasic XM suspension without HA. And maybe because the HA does not work as it should, the rear suspension is "too" soft and the complete rear part of suspension "strikes" directly into chassis and this is the noise which drives me insane.

Maybe it would be the best idea to connect XM to Proxia and find out what is wrong.

What do you thing about my "crazy" theory?

Thank you
FrenchLeave
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Post by FrenchLeave »

I don't think your theory that the hydractive isn't working is feasible. In HA1 the default setting with no power sets the system into "sport" (hard) mode. The fact that your car seems to be in permanent soft mode suggests that there is a continuous 12v supply from the control computer.

You can try disconnecting the wire from the control valve to see if it then reverts to hard but I wonder if you have air in the system - try the celebrated citaerobics.

If the rear spheres and the height control valve are OK, there is no way that the suspension arms can be running on the bump stops.
406 V6
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Post by 406 V6 »

Did you mention 20 seconds intervals in the ticking? That's extremely low, you should refill/substitue the acc sphere.
One thing: is it possible that you have non HA spheres in your car? They would sure give it a soft ride!

BTW, welcome to our comunity! :D
Francisco
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