V6 EXCLUSIVE FOR SALE

[xantia_v6]

I had not noticed that any XM suspension bush is as-yet unobtainable from after-market sources. It would be interesting to know which part he is talking about.

[Dean]

Only thing I can think is the arb bush housing is broken which would need to be sourced used or machined up, the other things that are tricky to get are rear subframe mounts for the mk 1 if I remember correctly.

D

[xmexclusive]

The ARB bush bottom housing is machined from aluminum.
They also support the rear of the front wishbone.
They have a long history of failing by cracking.
I can remember supplying a pair to a member in Scandinavia to use as a CNC pattern.
He made his replacements from Stainless steel.
That must have been over 10 years ago.
These items are handed but be aware if you source from France that there are also two different angular types (Hydroactive & Non Hydroactive).

John

[markysimon]

The ARB bush bottom housing is machined from aluminum.
They also support the rear of the front wishbone.
They have a long history of failing by cracking.
I can remember supplying a pair to a member in Scandinavia to use as a CNC pattern.
He made his replacements from Stainless steel.
That must have been over 10 years ago.
These items are handed but be aware if you source from France that there are also two different angular types (Hydroactive & Non Hydroactive).

John

That's it – the ARB bush housing! I live in hope, but also as by now you'll know, in semi-ignorance of Citroen technology!

Cheers – Mark W

[xmexclusive]

Hi Mark

Which side is needed?
Send me a PM.
Never visited Arnoud so might be worth a trip.
Known about him by reputation for many years now.

John

[Lwdajo]

This is interesting Mark - I have had a similar issue since I acquired a Mk2 2.1TD in March. It's been away from me since May with Chevronics, and still exhibits non-XM suspension behaviour over potholes/sleeping policeman, essentially sudden changes to road surface.

I've just asked them to fit the normal/sports LED from ECU through to the dashboard, but I'll pass on what your garage has found.

Cheers,
Lee

[Dieselman]

If if it is switching into soft mode but still displaying hard characteristics then the fault is likely to be hydraulic system pressure.
If the pressure is low the rise of pressure in the suspension rams overcomes the hydraulic block pressure so closes the shuttle valve.

Monitoring the HA sensors is a good tool for diagnosis.

[White Exec]

A very sudden change in road surface height (step up or down, pothole, speed ramp...) can cause rear suspension in particular to 'thud' as it takes the obstacle in firm mode.

This can happen if the glitch is taken anything other than at moderate speed: the front suspension (ARB/body movement sensor) detects rapid movement as it traverses the obstacle still in soft mode, but switches the system into firm in time for the rear suspension to cross the same glitch in firm. Hence the rear-end thud. Suspension LEDs (when fitted) confirm this really clearly.

One solution is to take such surface changes at reduced speed: the thud will not usually happen.

Will is right too about a low system pressure aggravating this phenomenon. If (particularly rear) hydractive/wheel sphere pressure momentarily rockets (as a result of the wheels going over a sharp lump), this can be enough to lift the centre regulator valve off its seat (sphere pressure momentarily higher than system pressure) and put that axle into firm . . . even though the EV (and any LED) remains powered. So, at the very moment you need things to be soft, they aren't.

One cure for the latter is to fit the late Xantia hydractive regulator valves, which are immune to differences between sphere and system pressure. With these fitted, rear-end crashes can only be brought on by 'excessive' vehicle speed (= rapid body movement), and so ride is much more predictable.

[Dieselman]

One solution is to take such surface changes at reduced speed: the thud will not usually happen.

30kmh/18mph being the threshold.

Disconnecting either the speed sensor or the accelerator position sensor should force soft mode, which will eliminate the electrical control side.

Air in the hydraulic fluid will cause the system pressure to be low so cause crashy ride.

[White Exec]

Air in the hydraulic fluid will cause the system pressure to be low so cause crashy ride.

That's right, because any air in the fluid is compressible (which the fluid is not), and so a momentary high pressure shock from a ridge has an easier time of flicking the valves open, into firm.