Xantia suspension.

trooper30 · Unread post by **trooper30** » 14 Dec 2009, 09:24

Morning fellas. Right in the week I have had the Xantia the rear suspension seems to have stiffened up a little and whne the cars parked up over night , or for a few hours the back end sinks to the floor, rises up ok on starting the car.
Could the stifness and the sinking be related?
Cheers fellas

addo · Unread post by **addo** » 14 Dec 2009, 10:02

I'd think they're not too related. A few people here (rougher roads?) have experienced internal failure of the rear anti-sink valve. It means the car doesn't stay up well for that long.

Another possibility is a worn (out of spec) regulator - your main system pressure may not be correct.

citronut · Unread post by **citronut** » 14 Dec 2009, 13:51

trooper30 wrote
"the rear suspension seems to have stiffened up a little"

do you mean it is/has become firm/hard/er whilst set at the normal drive hight,

if the suspension goes to all the diferent hights and settles as it should, then the first thing i would do is fit a new pair of rear spheres,

regards malcolm

Citroenmad · Unread post by **Citroenmad** » 14 Dec 2009, 18:03

The siniing scould either be the anti sink valve has suddenly stopped working, or the anti sink sphere has lost all of its pressure.

Best thing to do is get all the rear suspension and anti sink spheres checked for pressure or replaced.

DickieG · Unread post by **DickieG** » 14 Dec 2009, 18:21

Citroenmad wrote:The sinking could either be the anti sink valve has suddenly stopped working, or the anti sink sphere has lost all of its pressure.

Best thing to do is get all the rear suspension and anti sink spheres checked for pressure or replaced.

Erm that's not quite correct, the anti-sink sphere has no effect upon the sinking of a car, its purpose is to act as a reserve of pressure for the rear brakes in the event of a sudden loss of hydraulic pressure. Its only called an anti-sink sphere because its only fitted to cars with anti-sink.

I agree with a faulty anti-sink valve for the sinking, and for the rear sphere pressure being low (as long as the car is at normal ride height) for the stiff/firm ride.

Citroenmad · Unread post by **Citroenmad** » 14 Dec 2009, 18:59

There was a fairly lengthy thread on this topic not too long ago.

The antisink sphere does have something to do with the anti sink valve, hence its name. It keeps the anti sink valve closed, this is its main function. It does have a slight influence on the brakes i think if the car is carrying extra weight, but its mainly for operating the anti sink valve.

If the anti sink sphere is totally flat then it will not be keeping the anti sink valve closed.

In actual fact, cars with anti sink fitted have no brakes once the pressure has been lost from the system, when the engine has been turned off. As my neighbour found out when he flew backwards through his garage door while pressing on the brakes in his then new xantia estate, the roll the car backwards slightly without starting the engine. Cars without anti sink still have a balance of pressure to work the brakes for a short time. As the antisink valve isolates the pressure. This is one reason on later cars, C5s etc, the brakes are not connected to the suspension system.