Hard Suspension Diagnosis

[jamieb]

The suspension on my replacement R reg 2litre turbo hatchback is definitely too hard. Car judders over bumps and wobbles stiffly on uneven surfaces - not a magic carpet ride at all. I've replaced four wheel spheres with no significant improvement.

From what I can see, there are any number of different possible causes. is there a systematic way of checking, running from the most common to the most exotic?

eg:

1) Wheel spheres - check to see if flat
2) Centre sphere (?) - ditto
3) Electro valve (s) sticking (how to check?)
4) Flow distribution valve faulty (How to check?)
5) Hydraulic pressure regulator faulty (How to check?)
6) Electronic sensors faulty (How to check(?)
7)Solenoids (How to check?)
7) er.. anything else?

I was thinking of trying to build this into a diagnostic toolkit for dummies (ie novices like me), with appropriate action. Is this feasible or is the expert opinion that diagnosis and solutions are too complex for general approach?

Failing that, any advice to improve the ride?

[Robin]

jamieb, by the time we had got to the series 2 R reg vehicles many of the earlier gremlins had been sorted and the general reliability of the car had improved beyond recognition. Before you start to suspect the individual components I suggest you carry out a few basic maintenance jobs first.
You have replaced the wheel spheres so I suggest you do the following -
Bleed the brakes through to remove any air.
Carry out a full LHM change using the approved flushing oil and keeping it in the system for at least 500 miles bleeding the old LHM out by bleeding the brakes through.
The new LHM needs to be bled through the whole system and all brakes bled through again until the new LHM is flowing freely.
If you still have problems then you can be assured that the systems are not fighting minor blockages, many problems can be caused by poor flow rates from dirty LHM or sludge.
Robin

[Peter.N.]

If the outer spheres needed changing so do the centre ones, they are responsible for the soft ride, if they are flat you are virtually running in sport mode all the time as when the solonoid valves open there is no extra cushioning from the centre spheres.

Peter.N.

[noz]

Hi Jamieb,

Here's my best bet at an investigation sequence:

1) Wheel spheres. Easiest to check & replace if necessary. You say you have replaced them. Was that with new spheres? Were they correct for the model and year in question? There are unfortunately a few permutations depending on engine and year variants.

2) There will be two centre spheres - one at the front and one at the back. Both affect the suspension considerably. These two must be fully charged to give you the 'magic carpet' ride.

5) Regulator (accumulator sphere) - the way in which the centre spheres electrovalves work make them dependent on high pressure being produced by the pump/regulator combination. It is very important therefore that the accumulator sphere is also fully charged.

7) Solenoids - the best and easiest way to check the two solenoids on the two centre hydractive spheres is with your ears. They make a distinctive electrical buzz when operating which you would not mistake for anything else if you heard it. Get the car on some ramps and switch on the ignition (but not the engine). THe buzz will be clearly heard and is very easily identifiable as to whether it is front, back or both.

The next most common problem with hydractive is the failure of a small 20p device (diode) buried in the plastic casting of the solenoid valve mounted on each electrovalve. The failure of this diode eliminates the return path of the short circuit current caused when the power is switched off to the valve and the electromagnetic field collapses. The induced current finds its way back to the solid state relays in the ecu and eventually overheats them and thus causing failure. Read elsewhere on this forum for the fix to this problem particularly in the self help section.

6) Electronic sensors - these are monitored for proper operation by the ecu. If any fall outwith their programmed parameters the ecu notes it as a fault and keeps a record in its memory. By plugging the car into a proprietry computer (usually in a Citroen garage but some in private hands) which will interrogate the ecu and tell you what the last 20 recorded faults were. I suggest this is done as a matter of course. Keen garages may charge between 20 and 60 pounds for this priviledge but some benign garages will offer to do this for free. This simple test may save many man hours of otherwise fruitless investigation.

er....that's it

cheers

noz

[jamieb]

Plenty to be getting on with!

The car was an odd one - full service history, new Michelins (stuck on as incentive by dealer maybe) but all exhaust pipes rusted through and so much wierd slime in the windscreen washer system it hardly worked at all.

Given that, it makes it more likely that both spheres and LHM were neglected over time.

I'll keep you posted. Thanks to all.

[xmexclusive]

Hi

Slime in the windsceen washer is a sign of ownership by someone who used washing up liquid and tap water instead of washer fluid. Expect all the other maintenance to have been done on the cheap if at all.

Regards

XMexc

[jamieb]

Ha! LHM is piss yellow rather than pea green. Should have checked that first of all. I assume this is sign that not all is right ...

JB

[xmexclusive]

Hi PB

I doubt that the LHM has been topped up with washing up liquid (too expensive) it just will not have been changed and gone yellow with age unless someone topped up with ordinary brake fluid. Unfortunately all things are possible and go unrecorded on a vehicle history. Sounds like a flush of the hydraulics for 500 miles ,refill with new LHM, then see just the real faults (if any) in the hydraulic system.

Regards

XMexc

[jamieb]

Maybe someone tried to flush it out the hydraulics with Fairy. Should have checked the windscreen washer reservoirs for LHM.

Just to nail this down, is yellow LHM ineffective or does it merely mean it's old? I'm going to change it anyway but am curious. The excellent garage I go to - Brodie Engineering in NW London - tells me that yellowing happens in XM's and Xantias but not in CX's and DS's.

Tara

JB

[Peter.N.]

It will still work (LHM not Fairy liqid) buts gets all sorts of gunge in it which clogs the filters amoung'st other things.

Peter N.

[jorgy9]

One important factor you ommited from the check-list is that the vehicle rides at the correct height. This depends on height correctors linkages & linkage bearing being sticky. It's not rare that they stick to a higher than normal position, where the suspension naturally feels harder, even with brand new spheres. Each height corrector linkage has 1 metallic bearing which gets rusty with time and makes the whole mechanism "heavy". I bought replacements for mine (cheap thing), have now to find the time to do replace them.

George

[wirdy]

I've come to the realisation that my suspension is far too hard, it judders over bumps, clonks, etc. and I think my rattles are being caused by this problem - it's not any of the front susp ball joints, track rod ends or ARB links because they're all brand new.

So from this thread I see that spheres are the first port-of-call. I've ordered new fronts, rears and centres. The prev owner replaced the spheres sequentially during earky 2005, but I need to discount them I suppose - that's why I'm fitting known good ones.

My one question is.... electrovalves are buzzing quite happily on the ramp - could the valves be inop and the solenoids still buzz?

[Robin]

Wirdy, I have one here on my desk dismantled, solenoid that is. I think it is fair to assume that if they are buzzing happily then all is well with the moving parts. There is a fine filter at one end if you have not got round to the flush and run followed by new LHM then I would suspect that gunge is affecting the flow through the filter. My own XM has now had Hydraflush in it for over a thousand miles because I cannot find time to change it for new LHM and I have to say that the improvement is quite encouraging.
I really must put in the new LHM!!!!!!!!!
R

[wirdy]

Ta Robin. i've changed the LHM but haven't flushed yet.

Put new spheres on last week without any noticeable improvement. Didn't get time to find the rear centre, but will do next time on the ramps.

Hydraflush next then. / do Comma make a version of hydraflush??

This post has been edited by wirdy on December 28, 2006 12:04 am

[Robin]

Not sure Wirdy. Mine is from GSF and comes in a 5 litre can with all the words in French!
R