Citroen XM Forum

White Exec wrote:Don't forget the centre spheres (front and back) which is where the softness really comes from.
Neglect those, and it'll always be knobbly.

Am I right in thinking "comfort" centre spheres will have no effect on sports mode or cornering prowess given that the computer locks them out, but will improve the ride in a straight line or sweeping bends? Can you replace JUST the centres with comforts, and leave the rest as standard? Or is there no benefit to doing so?

I wondered that myself. Sport mode seems to make little or no difference on my Series 2 so perhaps just refreshing the centres will do the trick. I certainly wouldn't fit comfort spheres to the four corners.

Nor would I, because my understanding of how the system works is that it relies upon the corners to be firm and the centres to introduce necessary squidge.

Sam Skelton wrote:

russ92xmsed wrote:We will need you RP number... Stamped in the passenger door jamb. Then I can add that for you.

No worries chap - I'll get that for you tonight. Am I right in thinking I can trace the build date using this?

Great. Yes you can. You can find an orga calculator.. Google it!... And you will find it's birthday.


When in normal mode, all six spheres are operational. When in sport the system locks out the middle spheres. So H1 cars are in sport mode and therefore harder ride. In series two cars, the system doesn't lock the centre spheres out permanently. It changes the perimeters of the system and puts it into sport mode more often when you drive harder.

All I now about comfort spheres on the XM, is they make the car quite wollowy.


There is something about the Montego that seems to be maturing like a fine cheese!... It doesn't look too old.... Infact quite a neat design for it's era.
Colour is everything with them though. Brown and beige are not their friends!

I want wallowy spongy Citroeny suspension in a straight line, given the state of Fenland roads. The back's pretty much perfect but there's a little harshness through the nose. Wallowy in the corners CX style could be fun but I like the dynamics of the XM. Would it be ill-advised to fit a comfort centre to the front only?


The pet is blue, though the pic doesn't make it that clear. The diesel auto prototype is burgundy, though for comic effect I tell people it's a brown Montego diesel automatic estate. After all, it's social death at 24 Montego's a conservative shape, which means it never looked cutting edge but equally it didn't date as sharply as things like the Sierra. It's not thrilling to look at, but it's handsome!

H1 - quickly identified by the slider switch reading Auto and Sport
H2 - slider switch reads Normal and Sport

H2 was introduced across all Hydractive-equipped models Feb.1993, from RP5929.

H1
Engaging Sport puts the suspension into Firm mode, locking out the two centre (Hydractive) spheres. All suspension springing is down to the four corner spheres. Ride remains Firm while switch is in Sport position.

H2
Engaging Sport works differently. Parameters for automatically putting the system into Firm (accelerator position, body movement, speed, etc) are shifted to a different set of figures, with different thresholds.
So, for example, in Sport mode, the car will more readily automatically switch to Firm as you take a bend at speed, or boot the accelerator.....but when that condition is over, the system automatically reverts to a Soft ride, even with the switch in the Sport position.

To be accurate, the system was originally dubbed Hydractive. When Hydractive II appeared (RP5929), many folk simply referred to the versions as Hydractive I and Hydractive II.

Properly set up, with the right spheres at the right pressures, both systems offer a really comfortable ride. You are right in avoiding Comfort spheres for the corners, as these would not control body movement sufficiently. If the centre spheres are properly gassed, there is plenty of comfort available.

It would be possible to fit an alternative spec sphere to the front centre (possibly of larger volume and different pressure) to modify the degree of softness there, but I would advise that you get the spheres into good standard spec and pressure first, and then decide whether you need to pursue this.

Spheres and gas pressures should be checked at least every three years. Plenty of advice on the site for checking whether things have gone wrongly firm, Sam. You're about to have a lot of fun!

RP6045 - meaning mine was built on 28/5/93.

Another birthday, then!
Do add that RP number to your signature/profile....helps later.
So, now you know you have Hydractive II.
Will e-mail you a couple of useful bits to read.

I bought my first XM with comfort spheres.
It was fine on French roads or good main roads. I left them on for about a year? if remember correctly and changed the front ones. The rear ones are still on the XM and have been regassed. That's fine but no good to you since your rear is fine already. It's OK now but not better than the second diesel xm. I don't notice any difference with the second XM. I did try briefly to have the front comforts on the dieselt XM. It again was good on good roads but not on bad ones and it did get the tendency to wallow, like it did on the other car as well. I wouldn't opt for comfort spheres though I had them on my xantia which was fine on that car. they were only slightly altered at the time by drilling the centre holes a tiny bit.

The brand of spheres can make a significant difference to ride quality.
As your car had H2, it would be worth checking the front electrovalve is actually functioning and fitting diodes to the harness or circuit board. Fitting the larger, 500cc, centre sphere would make it softer, but it may bottom out.

Your car should have 450cc corner spheres.