Strange rear end

Kman · Unread post by **Kman** » 22 May 2009, 10:20

My rear end began to behave strangly after the car had been standing still for a couple of weeks. It's rather firm and gives poor comfort under certain driving conditions (sharp irregularities e.g. pot holes, joints). Sharp turns on uneven surfaces makes the car rock sidewise, but this may be the normal operation of the activa system.

Corner and center spheres are brand new, IFHS (they're tagged XA30RY etc.). The rear hydracitve unit makes a very audible "clunck" 30s. after the door is shut. The strange thing is that I'm able to depress the rear of the car to the bump stops with my own bodyweight before and after the valve shuts. Also, the once familiar drop of the rear end after speed bumps, when the centre sphere is reconnected, is gone.

Since I recently replaced the two dead corner spheres, I'm uncertain as to how much suspension travel they should give w/o the centersphere.

FYI: The car uses hydraflush at the moment.

Regads

Kristian

KevMayer · Unread post by **KevMayer** » 04 Jun 2009, 16:59

It sounds like 2 possibilities.

1. The new corner spheres may be the wrong spec. Could they be for a non hydractive Xantia.

I say this because the front corner spheres on my Activa were found to be the ones for a non hydractive Xantia. I could push the front down with the electrovalve on or off. This was done by the previous owner to compensate for a faulty electrovalve which meant the front was always in hard mode. I did the diode mod to sort out the electrovalve.

or..

2. Your rear electrovalve is faulty and always in soft mode. This isn't likely though because they usually stay in hard mode when they go faulty.

So, I'd be inclined to double check the new corner spheres.

Kman · Unread post by **Kman** » 05 Jun 2009, 15:24

Since posting, I have experienced that the rear end eventually firms up as it's supposed to. Also, the car usually remain in what seems like hard mode from a few second to a minute after starting, and then goes softer. Could be a sluggish HA valve. What is the chance of it staying mid-way between two positions, thus partly restricting flow to the middle sphere? And shouldn't any sluggishness be sorted out by the hydraflush?

When it comes to the spheres, using non-HA spheres should give opposite symptoms, i.e. too soft ride. When ordering and changing corner spheres I used a fair amount of time checking specifications, to avoid fitting ordinary HA spheres, which the previous had done. So I'm pretty sure they're the correct type.

Could the hydraflush have anything to do with it, because of small differences in viscosity? I guess I will find out soon enough when I change back to normal LHM.

Kristian

MikeT · Unread post by **MikeT** » 05 Jun 2009, 18:38

If your system has enough sludge to cause restrictions and you're currently running on a cleansing agent then you might find such abnormalities being temporary and dynamic.

Do you practice citroebics? It might help shift the problem sooner. Wouldn't hurt to check the LHM filters every few hundred miles too as the dirt is flushed around the system. That's what I'll be doing when I get mine back on the road as I've learnt dirty filters can make a noticeable difference. How long are you planning on leaving the hydraflush in?

Kman · Unread post by **Kman** » 20 Jun 2009, 01:35

I will leave it in for about 2000 km, although I can't say I have experienced any improvements the lately (at 1000 km now), compared to the inital response to the hydroflush (e.g. decrease in waiting time before the STOP light came off)

Kristian