C5 Suspension Spheres.

[StevieOMG]

I have a Mk1 C5 estate that is now eight years old. Can anyone advise how to check whether the spheres need replacing. Recently I have started getting a small amount of vibration through the steering and can feel every bump and pot hole on the front. Wonder whether its now time to get new spheres to bring back the carpet feeling. Its due its MOT in a couple of weeks son now appears the best time.

Any advice greatly received.

[Citroenmad]

You can get them pressure tested which will tell you what condition they are in. However if you have noticed a deterioration in ride quality then it might just be worth replacing them as they could be due.

If you know what a good C5 feels like then you could try bouncing on the corners of the car to see if you can detect a firm or springy quality to it.

[Gibbo2286]

Before you blame the spheres look elsewhere. this from the Citroen manual for the C5.

The suspension spheres are of the "slimline" type .
The suspension spheres are equipped with multi-layer diaphragms which give them an unlimited life .
The sphere has a safety pre-form in its upper part .
In the event of bursting through overpressure, the pre-form prevents projections of metal pieces .

[DickieG]

Before you blame the spheres look elsewhere. this from the Citroën manual for the C5.

The suspension spheres are of the "slimline" type .
The suspension spheres are equipped with multi-layer diaphragms which give them an unlimited life .

That reads just like the Xantia manual on automatic gearboxes being sealed for life and not needing fluid changes, we/Jim know what that results in

[myglaren]

I have a Mk1 C5 estate that is now eight years old. Can anyone advise how to check whether the spheres need replacing. Recently I have started getting a small amount of vibration through the steering and can feel every bump and pot hole on the front. Wonder whether its now time to get new spheres to bring back the carpet feeling. Its due its MOT in a couple of weeks son now appears the best time.

Any advice greatly received.

I get this sometimes - it comes and goes. It has been quite noticeable the past couple of days. More from the rear than the front.
My daughter's Rover 75 is softer/smoother over potholes etc.

Loading the car up to the gills with heavy stuff for a few (50ish) miles gives a huge improvement.

[Citroenmad]

Before you blame the spheres look elsewhere. this from the Citroën manual for the C5.

The suspension spheres are of the "slimline" type .
The suspension spheres are equipped with multi-layer diaphragms which give them an unlimited life .
The sphere has a safety pre-form in its upper part .
In the event of bursting through overpressure, the pre-form prevents projections of metal pieces .

I wouldnt take any notice of that Sounds like blurb which might persuade a conventional suspended car driver to buy one with this mad suspension to me

Citroen did originally say that the system requires no servicing for 125K miles or 5 years. I have know C5s need spheres replacing at 50K miles but 6 years old and ones which go on for a much much longer. Many C5s do still ride well but there are ones riding badly now.

I have only had to replace two spheres on a C5 in the time I have driven then (which includes 5 C5s). That was only due to that car having cheapo spheres fitted which one had gone hard. However the cheapo spheres were fitted by the previous owner due to the originals getting firm.

The multi-layer spheres were on XMs and Xantias at times too, they do provide a much much longer life but certainly not unlimited.

I looked at a 52 C5 with FCSH and only 49K miles recently, the rear spheres were very poor giving a very bad ride and a very springy bounce when pressing on the back of the car.

There seems to answer to how long the spheres last, depends upon the use of the car more than anything.

They are by no means a fitted for life item, but they do last far longer than ones seen on previous Citroens (excluding the multi-layer ones).

[daviemck2006]

My one has a firmer ride now than it had, in fact has started giving an odd clonk and bang from the rear at 8yrs old and 103000 miles. Done quite a bit of towing so I'm presuming suspension will need looking at shortly. Needs discs and pads on rear as well, and got the usual caliper problem, as far corroded the calipers are just scuffing the wheels, and I cant move the bolts. gonna cost me soon I think. Still 6 months mot, might get sold soon without the work done, or be fixed and kept longer dunno yet.

[cachaciero]

Before you blame the spheres look elsewhere. this from the Citroën manual for the C5.


The sphere has a safety pre-form in its upper part .
In the event of bursting through overpressure, the pre-form prevents projections of metal pieces .

You have all missed the important bit

The "safety" bit is actually a spike in the top of the sphere, when the sphere gets too soft the spike pierces the membrane. the sphere then instantly gets very hard

So from this it can be deduced that sphere failure when it happens on a C5 should be very obvious.

cachaciero

[Citroenmad]

So from this it can be deduced that sphere failure when it happens on a C5 should be very obvious.

cachaciero

Sphere failure yes, but a loss in ride quality will happen way before them. You dont wait until they fail to replace them ...

[cachaciero]

So from this it can be deduced that sphere failure when it happens on a C5 should be very obvious.

cachaciero

Sphere failure yes, but a loss in ride quality will happen way before them. You dont wait until they fail to replace them ...

Maybe but there is no doubt, in my mind anyway, that the leakage rate of the C5 spheres, with the composite mylar/ rubber diaphragm is MUCH reduced over the older type and Citroens claim of virtually unlimited life is close to the truth.

As the volume of gas is obviously less than that of the old style there is less gas to lose and I believe that when they do start to leak they probably loose gas quite quickly.
So I suspect that the period between good ride quality and rock hard may not be as long as you may think.

cachaciero

[cachaciero]

The original question does not specify which model of C5 because if it's an Exclusive it will have the centre sphere and regulator. The problem as described could well be failure of the regulator.

cachaciero

[Paul-R]

The original question does not specify which model of C5 because if it's an Exclusive it will have the centre sphere and regulator.

I don't know about all the petrol engined Exclusive models but only the 2.2HD1 has the 3+ suspension - the 2.0HDi is ordinary 3.

[StevieOMG]

It's a 2003 LX so only has the standard suspension. Having bounced the car in all four corners suspension seems fine. Can however feel every bump in the road at front so maybe something else is the issue - droplinks? Car has now done 113K and apart from servicing and a washer pump has required nothing in eight years. I still propose to change the spheres as I believe that it will be of benefit and it deserves to have some TLC thrown at it.

[Citroenmad]

So from this it can be deduced that sphere failure when it happens on a C5 should be very obvious.

cachaciero

Sphere failure yes, but a loss in ride quality will happen way before them. You dont wait until they fail to replace them ...

Maybe but there is no doubt, in my mind anyway, that the leakage rate of the C5 spheres, with the composite mylar/ rubber diaphragm is MUCH reduced over the older type and Citroëns claim of virtually unlimited life is close to the truth.

As the volume of gas is obviously less than that of the old style there is less gas to lose and I believe that when they do start to leak they probably loose gas quite quickly.
So I suspect that the period between good ride quality and rock hard may not be as long as you may think.

cachaciero

They do run a slightly loer pressure than older Citroens, however pressure lose will be gradual and not once it starts to lose pressure it will do so quickly. Why would that be? Its like air in your tyres, they go down over time but once they start to go down the air loss does not get faster. Yes there is less gas to lose but there is also the thicker diaphragm to keep the pressure.

C5s get bouncy and hard, I have only been in one C5 on poor spheres however. It was not the case that the spheres had popped, but it was very hard to ride in and bounced to much when pressing on the front and rear of the car. Of course the seller thought it felt fine but comparing it to my C5 it was totally different and needed replacement spheres.

[cachaciero]

They do run a slightly loer pressure than older Citroëns, however pressure lose will be gradual and not once it starts to lose pressure it will do so quickly. Why would that be? Its like air in your tyres, they go down over time but once they start to go down the air loss does not get faster. Yes there is less gas to lose but there is also the thicker diaphragm to keep the pressure.

In the older spheres the diaphragm was / is a relatively thick piece of rubber, over time at a molecular level Nitrogen "seeps" through this rubber, and so the sphere goes flat / soft.
Interestingly the rate at which this happens is almost certainly tied to rubber characteristics which may explain why some after market spheres were reputed to go soft quite quickly.
I suspect but don't know that the sphere volume was chosen such that the suspension characteristics remained acceptable for a certain amount of gas loss, the suspension not being compromised until max cylinder stroke results in the diaphragm effectively bottoming out on the shell.
On later Xantia and XM spheres Citroen introduced a sphere with a composite membrane consisting of a rubber plastic sandwich, I have it in my mind that the plastic is / was mylar but can't find a reference for that.
These spheres were the prototypes for the C5 spheres, which are little different.
The mylar film molecular structure is such that at this level it is virtual impossible for Nitrogen to "seep" through at a molecular level and thus the sphere will hold gas for a considerably longer period than the old rubber ones.
Given the longer life maybe it was that Citroen decided that there was no longer a requirement to have a "reserve" of gas which allowed a volume reduction in the sphere, the reduced compliance of the new diaphragm may have had a bearing on this as well.

However all things can fail and Mylar film is no exception, if the mylar splits then the only thing holding in the gas will be the rubber which being thinner than in the old spheres will allow nitrogen profusion at a higher rate.
My conjecture is that once a C5 sphere starts to go flat they will go flat comparatively quickly and because there is not much reserve of gas it will quickly get to the point where the diapraghm will get "spiked" but until it gets spiked the suspension will be acceptable, simply because the required pressure will be maintained in the sphere until it's spiked.

In conclusion it is my belief that C5 spheres are good until they pop, you will not be able to drive for a long time on flat spheres and poor ride as you could do with earlier generations, the system doesn't allow it.

C5s get bouncy and hard, I have only been in one C5 on poor spheres however. It was not the case that the spheres had popped, but it was very hard to ride in and bounced to much when pressing on the front and rear of the car. Of course the seller thought it felt fine but comparing it to my C5 it was totally different and needed replacement spheres.

That's an interesting anecdote my immediate thought is was it fitted with the correct spheres? In my own case I can only say that as a matter of course when I purchased my C5 @96K I changed the front spheres it made not one jot of a difference the new ones were no better than the old ones, have just had to accept that by comparison with an XM it just don't ride so well From that I believe that @96K the original spheres were still good.

cachaciero