C5 centre spheres

ncoll · Post by **ncoll** » 02 Jul 2007, 18:23

Hi Folks,
I've purchased centre spheres for my C5 2.2hdi estate (01 plate). Should the rear have no valve like an accumulator sphere and the front have a valve like front strut sphere?
I don't want to get underneath armed with wrong bits!
Front is marked C562 FR
Rear is marked C544 RQ
Cost if anyone is interested was £36.94 each.

bencowell · Post by **bencowell** » 02 Jul 2007, 22:43

Are they made by IFHS?

AndersDK · Post by **AndersDK** » 02 Jul 2007, 23:15

Yes - these spheres are made by IFHS :
http://www.dworzak.at/Kataloge/KATALOG_ ... N_2005.pdf

C562FR :
C5-mk1 break (estate) HA3plus front center on 2.0i16v, 2.0hpi, 2.0hdi, 2.2hdi
C5-mk2 break (estate) HA3plus front center on 2.0i16v, 2.2hdi

C544RQ :
C5-mk2 break (estate) HA3plus rear center on 2.2hdi

You will notice that IFHS spheres have a part no telling :
C5xxxx - Citroen model applicable on
xx62xx - nominal inflation pressure
xxxxFx - in most cases denotes front of car
xxxxRx - in most cases denotes rear of car
xxxxxQ - sphere type variant denominator

The spheres you've got are correct for a mk2 C5 estate 2.2hdi.
Your C5 will have a 'sport' mode switch for the HA3plus suspension system.

ncoll · Post by **ncoll** » 03 Jul 2007, 09:19

Hi Folks,
Thanks for quick replies, when the weather dries out a bit I shall get on with the job. Meanwhile I will check to see if my homemade chain wrench fits these new style spheres!
Once again thanks for the info.

Mandrake · Post by **Mandrake** » 03 Jul 2007, 11:36

While I won't dispute the PDF table Anders has found I have to question whether the front Hydractive centre sphere should have a damper valve in it ?

If Hydractive 3+ on a C5 is anything like Hydractive 2 on a Xantia the block that the sphere screws onto will have two damper valves built in to it and the sphere should have none.

The fact that the front centre sphere would have an additional damper valve while the back doesn't sounds suspicious.

Is it possible that you have the correct box with the right code but with the wrong sphere supplied in it ? (the PDF table only lists that part code as the correct sphere - it doesn't actually state the pressure or damper valve it corresponds to)

Can anyone else who has fitted new spheres on the front of a Hydractive 3+ C5 confirm or deny the presense of a damper valve in the sphere neck of the "centre" sphere ?

Regards,
Simon

AndersDK · Post by **AndersDK** » 03 Jul 2007, 13:02

Simon -

Your reflections on the center sphere with a damper valve are quite logic. But the damper valve does not mean anything on the downside in this context. It will rarely come into action, because it only operates by large amplitude pressure variations, like only a suspendend wheel can cause.

I would even say if the damper valve does anything, it does in fact help to give a better drive experience, as any 'pothole hit on high speed' pressure excursion will further be absorbed - should this alien damper valve come into action, i.e. if it opens up.

This discussion is however highly hypothetical - as we dont know if this sphere in fact SHOULD have this damper valve fitted on a C5.
- or do you happen to know this for a fact ?

Mandrake · Post by **Mandrake** » 03 Jul 2007, 21:09

AndersDK wrote:Simon -

Your reflections on the center sphere with a damper valve are quite logic. But the damper valve does not mean anything on the downside in this context. It will rarely come into action, because it only operates by large amplitude pressure variations, like only a suspendend wheel can cause.

I would even say if the damper valve does anything, it does in fact help to give a better drive experience, as any 'pothole hit on high speed' pressure excursion will further be absorbed - should this alien damper valve come into action, i.e. if it opens up.

Hi Anders,

My point is there SHOULD be two damper valves already in the control block going to that sphere - why add a third one to the sphere itself ?

Damper valves in the control block also damp side to side (body roll) movements, a damper valve placed in the neck of the centre sphere would only damp vertical body movements and not roll movements - one reason why they use two damper valves in the block in the first place.

I can't see why this would change with the C5...and only at the front and not at the back...doesn't make any sense.

This discussion is however highly hypothetical - as we dont know if this sphere in fact SHOULD have this damper valve fitted on a C5.
- or do you happen to know this for a fact ?

No I don't know for a fact, which is why I'm questioning to see if anyone else does know for sure...

I'm just suggesting it could be a case of a mislabeled sphere - something which you have often suggested when there is doubt of a sphere being correct.

Regards
Simon

AndersDK · Post by **AndersDK** » 03 Jul 2007, 22:50

Simon remember that the damper valve in the wheel sphere is not really a 'damper' valve in the sense of restricting anything.

It does in fact act the opposite way

It opens for more flow in/out the sphere cavity once you have large amplitude suspension excursions. In other words : it adds to - or 'widens' - the center hole in the sphere.

The damper valves in the hydractive system restricts flow to prevent roll.

Conclusion : the sphere damper valve has no negative effect on the center sphere function.

Mandrake · Post by **Mandrake** » 03 Jul 2007, 23:12

AndersDK wrote:Simon remember that the damper valve in the wheel sphere is not really a 'damper' valve in the sense of restricting anything.

It does in fact act the opposite way

It opens for more flow in/out the sphere cavity once you have large amplitude suspension excursions. In other words : it adds to - or 'widens' - the center hole in the sphere.

Hi Anders,

Not sure how you come to that conclusion...

Of course the damper valve restricts flow compared to not having a damper valve..... ? For small flow rates there is a lot of restriction, (just the small centre hole) for large flows there is little restriction. (All the holes under the washers)

Bear in mind that the diameter of the hole behind the damper valve into the sphere body is about 5mm.

The damper valves in the hydractive system restricts flow to prevent roll.

Conclusion : the sphere damper valve has no negative effect on the center sphere function.

The damper valves fitted in the Hydractive control blocks are of the EXACT same design as those fitted in sphere necks, except with slightly different calibration.

There is one between the centre sphere and the outlet going to each side, and they take the place of a normal damper valve in the neck of a sphere since one sphere is being shared by both sides...

Regards,
Simon

AndersDK · Post by **AndersDK** » 03 Jul 2007, 23:26

Errr ...

does that mean under certain conditions the hydractive system 'damper' (should we say restriction ?) valves - may suddenly open and allow large flow between the sides ? - the car would immediately roll over then
Or what have I missed here since that can not happen I know for sure

I really do believe that the hydractive system side-to-side valves are of a restrictive nature, with a complete block off whenever the flow reaches a set threshold.

In other words : exactly opposite to a wheel sphere 'damper' valve ?

Mandrake · Post by **Mandrake** » 03 Jul 2007, 23:39

AndersDK wrote:Errr ...

does that mean under certain conditions the hydractive system 'damper' (should we say restriction ?) valves - may suddenly open and allow large flow between the sides ? - the car would immediately roll over then
Or what have I missed here since that can not happen I know for sure

I know what you mean - the answer to that is twofold.... Body roll is a very slow movement compared to bumps, so body roll doesn't tend to open the washers on the centre damping valves, so it flows slowly through the centre hole.

Remember that on a non Hydractive system the left and the right side are piped directly together with no damper valves, and no restriction except for the small diameter piping!

For violent cornering which may open the washer valves by then the Hydractive system will have switched into the hard mode - which completely and utterly blocks left-right flows.

I really do believe that the hydractive system side-to-side valves are of a restrictive nature, with a complete block off whenever the flow reaches a set threshold.

Only if you consider the system switching to hard mode to be a part of this - in hard mode the cross flows are completely blocked.

As I said, the damper valves in the block are standard sphere type dampers, and they have a 3 washer stack on both sides and a 1.1mm bypass hole, and can be easily removed and refitted.

I've had them out and examined them before, and in fact to increase the damping of the "soft mode" slightly I have reduced the bypass hole from 1.1mm to 0.9mm - and this tiny change made a quite considerable change to the feel of the car in the soft mode.

(Increased rebound damping and reduced "float")

In other words : exactly opposite to a wheel sphere 'damper' valve ?

Nope, not opposite, because they are exactly the same construction...

Regards,
Simon

AndersDK · Post by **AndersDK** » 03 Jul 2007, 23:55

yep OK - I forgot switching to hard mode blocks the connection between sides...

And the center sphere is only connected in soft mode - where you have the relatively 'slow' flow. Since the sphere damper valve only opens during fast flows - it still does not matter on a center sphere - OK

BTW : there are no problems in using a wheel sphere as a standard accumulator sphere. Done it for a couple of years and forgot, until I thought the sphere should be saved when the car was scrapped. You may even find it advantageous to use one of the large volume wheel spheres as an accumulator sphere.

ncoll · Post by **ncoll** » 04 Jul 2007, 18:18

Hi Guys,
I didn't mean to start such a heated discussion, but I was perplexed at seeing a accumulator sphere with a valve in it.
The box and the sphere are both marked with the same number. I can't find anybody who has changed these spheres to get any info from. Only reason I am changing them is that I dont feel the ride is as good as any of the XM's I've owned. I know the wheel spheres have been changed 'cos I have the receipt for the job from previous owner.

AndersDK · Post by **AndersDK** » 04 Jul 2007, 19:22

Ahhh -

But this is not a heated discussion - at all

This is a brain storming with ideas & theories discussed - spiced with a few facts here & there

Yes - we (I) did in fact hijacked your thread doing thsi, I apologise for that

Unfortunately I can not promise I wont do it again

Wish you luck with the C5.
Please submit any feedback when you have tested the car for a while.