Dirty Lhm, 8th Sphere Or Front Height Corrector?, Rear end rising

[mark]

Thanks for that.

Over £700 was just spent at Marsh Citroen on spheres and associated works so I am reticent to replace all the spheres again. I left a message with Marsh Citroen office a week ago but he has not bothered his arse to get back to me.

Everybody including Pleiades are stumped.

Are you saying that GSF spheres, although correctly stamped, could have the wrong orifices.

This is a total pain in the arse as i'm trying to get the car finished but obviously reticent to spend money on bodywork while this is not resolved.

[kenhall1202]

For what its worth I fitted a full set of 8 GSF Amtex (including 4 'Comfort') spheres on acquiring my first XM some 7 or so years ago. I knew that the 'Comfort' spheres would probably make the car a bit wallowy but the behaviour of the rear suspension became totally silly and it would oscillate wildly as if there was no damping at all. I complained to GSF and they sent two replacement rear spheres by return without question (didn't even want the suspect ones back). On swopping them over I noticed that the centre holes in the dampers were much larger than on the replacements sent by GSF (and the originals which I was replacing). The problem went away after changing these two spheres and I have been happy with the 'Comfort' set-up. I repeated the GSF / Amtex complete sphere change again last year (buying them via GSF's ebay listing at a slightly cheaper price than via the catalogue) without any similar problems. I think that Amtex (whoever they are) seem to have occasional quality control / final inspection / identification problems and you may have been unlucky as I was.

Regards Ken

This post has been edited by kenhall1202 on August 16, 2007 08:29 pm

[DerekW]

Hi Mark,

Looking at your symptoms one at a time, you wrote that your car was pitching backwards and forwards under acceleration and braking. I suppose that some rising of the front under acceleration is inevitable, but the design of the rear suspension and the reaction to brake application at the back should cause the rear to squat, thus cancelling out the tendency to pitch down at the front. It sounds to me as if your rear brakes are not working, it is not unknown for the rear pistons to seize on XMs - I've had it happen on two of my cars.

As far as the handling being terrible is concerned, I think that the possibility of it being stuck in soft mode is a red herring as this would still give very acceptable handling.

Similarly, larger volume and/or higher pressure spheres will give soft suspension (greater suspension movement for a given input force), but not wallowing as this is simply a function of damper orifice size. It might be worth your while pulling off the two front suspension spheres and checking the size of the central orifice using small drills as go/no go gauges. If they are OK you might then consider repeating the exersize with the rears. You don't need to bother with the central (hydractive) spheres as their dampers are integral with the control valves, not the spheres themselves. I'm sure you are aware of the correct sizes but if in doubt I can provide them (the sizes, not the spheres!).

So once we've dispensed with the hydractive valves and the spheres and dampers, what's left? As has been suggested (by Peter, I think), some fault in the anti roll bar connections must be a candidate. But more and more I keep coming back to an impossible scenario where you have no damping at all. So how can you have no damping if the damping valves are present and correct? The only answer I can come up with is if you are damping the wrong fluid, air instead of LHM. If you had a pocket of air in each suspension cylinder it would produce the symptoms you describe. The system should be self-bleeding, but is it possible for the sytem to be continuously replenished with air? What if there is a leakin the supply to the pump? An even worse scenario has just occurred to me, what if you have air in only one or two units? That would give truly horrible handling.

I don't know whether this is a feasible explanation, but it might provide a discussion point.

Derek

This post has been edited by DerekW on August 17, 2007 12:00 am

[mark]

Thanks for all your time and help everyone.

Drop links - track rod ends, drop links and all associated steering ok. Watched mechanic check them after I changed oil and gearbox oil.

Rear brakes - new pads, 3 new bolts 2 new washers at Marsh Citroen 27 April 07. Do not know if the rear brakes are not working.
Will test.
Do feel like i'm going to touch the fence in parking space when stopping form a slow speed.
ABS - no error on dash but when Roy braked reasonably hard the front near side locked up with no ABS.

Spheres - front and rear suspension spheres central orifice to be checked.

Air in system / bleeding - when stopped front of the car leaks air and falls a little.

Leak in air supply to pump ?

Air in only one an two units ?

Bolckage / dirt in suspension pipe after regulator and rear height stripped and rebuilt ?

Glad i've got two 2.5's !

Cheers,

Mark.

[jorgy9]

Hi Mark,

have a look at post titled "Windscreen" by Colin in "Anythin goes chat". He suggests at some point that he overcame the "excessive travel and no damping" problem of his suspension for the MOT by removing his aftermarket ecu box, which I guess is Roy's box. Is there something happening here I wonder ?? Perhaps contacting him and hearing his story would be a good idea?

regards
George

[mark]

Thanks for that.

I'm going to do three ECU tests today,

Disconnect the ECU to see it is then permentantly stuck in hard mode.
Use the "radio trick" to test for the electro valve working.
Remove the aftermarket box and see whats happening.

On Monday i'm going to stand with the mechanic and go though all the list of possibilities.

Cheers,

Mark.