Citroen XM Forum

This is dangerously soft

The car is horrendously unstable if you get a push on to the point of tyre squeal

Nose dives if you brake any harder than normal

Yea its absolutley too soft. Not even id have it that soft..

maxferreira wrote: ↑

Sun Jul 24, 2022 5:30 pm

Nose dives if you brake any harder than normal

Prepare to be stunned once you have the correct spheres fitted. The nose diving with correctly working Hydractive isn't possible, the car stays level.

Hydractive1 under test.

yes you see i can't do that at all

i can't take roundabouts at more than 20 most the time

i note however, if i flick it into sport mode it does control itself a bit better, still far too soft but it's better, new spheres will certainly be a transformation

i can literally compress the front end almost to the bump stops just by pushing on it, which is hilarious

it feels like a conventionally sprung car with absolutely non existant shocks, especially the way it bounces

it doesn't recover from a bump instantly like the C5, it bounces a fair bit and i reckon it's struggling to cope

i suspect, it has a completely flat centre sphere at the front

If there is a change when sport mode is engaged the centre sphere isn't flat, though it may well be due for regassing/change.

Your car should have 450cc front corner spheres and 450cc front centre sphere.
My suspicion is it has 500cc spheres and the corner ones have 1.8mm damper orifaces, instead of 0.8mm ones.
Centre spheres are undamped, as the dampers are built into the hydractive regulators.

The more gas volume the softer the ride, the greater damper oriface the less stiff the damping.

The damper centre drilling is for long-slow undulations (low frequency), the spring washers are for instantanious shock absorbtion (high frequency).
0.8mm hole give 0.5mm squared of area, 1.8mm hole gives 2.54mm squared, so 5 times less damping, hence the car is not properly controlled.

Until you change the spheres, either drive in Sport mode, or pull the Hydractive fuse, to lock the car into hard mode.

that's a very informative write up, thank you

yes, for now i'll be driving it round in sport mode and see the reults and if it feels any more fcomfortable to drive

all spheres are getting replaced next tuesday, hopefully with good results

todays little task was trying to repair the blower fan again as it had stopped working

this time i tried replacing the transistor pack, to see if that would make a difference, i wasn't expecting much

removal was a pain due to rusted screws and i ended up just pulling it out and replacing the screws with new

once the old unit was removed, yes i could see why it might have been having issues

i'm pleased to report it works absolutely fine now! i must admit it does seem a little slow in gettting started on speed 1, but i imagine that is due to the motor still being a bit sticky due to lack of use

otherwise, hopefully this will keep working for a good time, i do note the air flow director knob doesn't seem to work that well, i've found a sweet spot of getting air through all vents at once, with a majority through the face but it doesn't seem to work well at all

just got home from work

i decided to try driving it home in sport mode and push it just a little bit

yep, completely different, nowhere near as much lean

so it seems hydractive does work

Being buit in 1993, RP6043, I have to keep reminding myself your car is a hydractive 2 version.
The sport switch won't force hard mode continuously, as it will with H1, but will make the system revert to hard more readily than in Auto.

If you want it in hard mode continuously pull the Hydractive fuse out.
Note the difference between H1 and H2 spheres. H1 have larger centre spheres and smaller, stiffer, corner ones, H2 has smaller centre sphere and larger, slightly more relaxed, corner ones, with slightly more overall gas volume. This was due to criticism that H1 was too stiff when in hard mode and the transition from soft to hard was noticeable.
One can use this information to tune the ride to your liking, either slightly more soft and luxuruious, or more sporting. Either way, an Xm is a surprisingly good hussler.

Nice fix on the heater fan module, it would be worth checking the intake duct isn't covered with wet leaves, as the old module appears rusty. The intake is in the left side of the scuttle.

Regarding the heater direction control, does it feel stiff and springy and doesn't adjust to the ends properly.
I suspect the flaps inside the heater box have jammed, but if the control feels loose and turns all the way readily, it may just need the cable adjusting.

It's a bit of a job to sort the flaps jamming.

See thread.
viewtopic.php?f=6&t=6292&p=71456&hilit= ... box#p71456

I tried to adjust it and I think a cable has popped off, so I need to remove the panel and take a look behind (job for the weekend)

Interesting RE the suspension, now, I’ve seen the multifunction display in some XMs display “automatic suspension” upon startup, mine displays “normal suspension” and “sport suspension” leading me to wonder how it determines it

If you’re in normal mode and you load up the front end a little and then brake sharp it doesn’t nose dive compared to if you just broke sharpish

4 days to go until the new spheres and I’m excited