xantia spheres pressure changes

wonderd · Post by **wonderd** » 21 Apr 2007, 20:58

I have looked at the opther topics here about different pressures and i understand that the more pressure there is in the sphere the softer the ride will be. (If i am wrong please correct me).
My question is about the size of the sphere - what is the difference between 55/400 and 55/500 ?

I have xantia 2.0L 16V non hidraactive, the front spheres are 55/400, what will be the change if i replace the sphere with a bigger one (500)

what if i just replace the 55 with a 50?

Mandrake · Post by **Mandrake** » 21 Apr 2007, 21:04

wonderd wrote:I have looked at the opther topics here about different pressures and i understand that the more pressure there is in the sphere the softer the ride will be. (If i am wrong please correct me).
My question is about the size of the sphere - what is the difference between 55/400 and 55/500 ?

I have xantia 2.0L 16V non hidraactive, the front spheres are 55/400, what will be the change if i replace the sphere with a bigger one (500)

Assuming the damper valves were the same, the larger volume would give you softer springing in the same proportion that the same volume and higher pressure would.

(Eg going to 10% higher volume would have much the same effect as going to 10% higher pressure)

However I question where you would get a 55 bar 500cc sphere with the right damping for the front of a Xantia ??? (AFAIK 500cc spheres were never made for the front struts of a Xantia)

what if i just replace the 55 with a 50?

Well, the two standard types for front non-Hydractive Xantia's are 55 bar 400cc and 50 bar 450cc, the latter type being the multilayer long life diaphrams. Because the larger volume one has proportionately lower pressure the actual springing rate works out to be almost identical. Does that answer your question ?

Regards,
Simon

AndersDK · Post by **AndersDK** » 21 Apr 2007, 21:20

In general you are right -

More pressure in the sphere means softer suspension.
But only to a certain extent. If the pressure is already optimised in the sphere for the car its fitted to - then you wont gain anything increasing the pressure.
This is because the sphere pressure is opted to divide the gas and fluid volume in the sphere equally when the car is normal loaded.

However if you increase the total sphere volume - it will widen the possible suspension excursions before the gas is compressed to dampen the movement. This will in general feels like a softer suspension.
Wether you are using 50 or 55 bar pressure has no meaningful difference - as both are within each others tolerance ranges when the spheres has been used a few thousand km.

I'm a bit confused that your dealer is offering you several different spheres ?
There is a lot more to spheres than just the volume & pressure - and your dealer should certainly know that !
The diameter of the center hole will have about the largest influence on how the cars suspension behaves - and feels like during drive. This is where things may become dangerous - to say the least

Firstly go for spheres with the Citroen specified center hole diameter, then the Citroen specified pressure. If you want a softer suspension go for the larger volume sphere.
If you want even softer suspension, then try a wee bit larger center hole (by 0.05mm - 0.1mm for instance). No more. As then the suspension may become that soft you can no longer control the car at speed.

Its the same as when you had your BX.

slim123 · Post by **slim123** » 21 Apr 2007, 22:11

Agreed with all !!!

The sphere is only a spring, the damping, ie the speed that the fluid goes in and out is controlled by the damper in the neck of the sphere.

The harder (more) shims, then the harsher the suspension will be.

The small hole in the centre is to let undamped fluid back and forth because you need this for cats eyes etc.

If for example you were to fit BX estate spheres to the rear of a BX saloon, (they are both 40- pressure but the saloon is 400cc and the estate is 500cc) you will find the ride quality realy good on normal roads. But what you will find is that every time you pull away, the rear mudflaps will scrape! Too much movement. This is because the rear cylinders on the estate are larger too, for load carrying capacity.

How do I know this?? Well, I tried it for fun, I also tried a set of accumulator spheres for suspension, just to experience the results!! dont try it, it gives a very wierd ride and bounces out of controll at speed.

Also worth noting that when the Xantis first arrived here in the UK, the front spheres were 400cc charged to 75-

Regards
Slim

wonderd · Post by **wonderd** » 21 Apr 2007, 22:56

how do i know what diameter the hole is? - it is not written on the box or on the sphere.
they are IFHS spheres and all it is written on it is this: XA50FH
There is also a code number 5 414051 10055 don't know if that means anything.

Mandrake · Post by **Mandrake** » 21 Apr 2007, 23:18

wonderd wrote:how do i know what diameter the hole is? - it is not written on the box or on the sphere.

No its not - even on genuine Citroen spheres. And as mentioned the washers/shims play as much a role in damping as the hole diameter. The only way to measure the hole accurately is if you have a set of small precision drillbits (0.1mm increments) simply by finding the largest one which you can insert in the hole...

they are IFHS spheres and all it is written on it is this: XA50FH
There is also a code number 5 414051 10055 don't know if that means anything.

Ah, now we're talking. Someone on the forum will hopefully point you to a sphere table for IFHS spheres which will give you the info you need. (I've heard of them before but not familiar with them)

Regards,
Simon

AndersDK · Post by **AndersDK** » 22 Apr 2007, 00:40

http://www.dworzak.at/Kataloge/KATALOG_ ... N_2005.pdf

XA50FH decodes like this :
XA---- denotes its a Xantia sphere
--50-- denotes the sphere inflation pressure of 50bar
----FH denotes its a front hydractive

type sphere

In the IFHS table of applications, this sphere type is listed for the following Xantia models :
hydractive 2.0i-8V ->10/93
hydractive 2.0i-16V ->10/93
hydractive 1.9TD ->05/95
The center hole would be 0.6mm
Obviously this type sphere is not suited for a non-hydractive Xantia. The suspension will feels rock hard during drive.

I suppose you would need a type XA55FC (1.5mm centerhole) for a non-hydractive Xantia. The earlier type sphere (as mentioned by Slim) would be the XA70FA (1.65mm centerhole) which I believe gives a softer ride.

Hope you are a bit closer to the facts now

wonderd · Post by **wonderd** » 22 Apr 2007, 06:42

Yes, thank you, i got it now.
I called the dealer and he will order me the right spheres for my xantia.

Last Q: what are comfort spheres? will they fit my car?

wonderd · Post by **wonderd** » 22 Apr 2007, 06:47

BTW, i wish mine was hidractive, only those cars are very rare in israel... as far as i know there is only 2 here, one is activa.

Maybe i could import all the parts and transform mine to activa...

Xaccers · Post by **Xaccers** » 22 Apr 2007, 07:58

wonderd wrote:BTW, i wish mine was hidractive, only those cars are very rare in israel... as far as i know there is only 2 here, one is activa.

Maybe i could import all the parts and transform mine to activa...

Isn't Citroen's rareness in your neck of the woods due to the plastic on the BX fading in the sun, so giving them a bad name?

wonderd · Post by **wonderd** » 22 Apr 2007, 08:36

Not at all, it has nothing to do with the plastics, it's the lack of good mechanics that know their way with citroens and the expensive cost of hidraulic components.
infact there are meny xantias and c5s and other citroens here, the fact that there is a bad name to citroen in general is correct, it is even worse then bad name - people that don't understand won't get close to citroen - even the mechanics don't like it.
but it's all the main dealer's fault, he is not doing enough here to fix the negative opinion.

With the xantia, the thing is that the dealer just decided not to bring any of the exclusive models to the country, guess he had his own reasons.
we besically have the SX model here through all the years, most are automatics with 1.8 and 2.0 liter engines. almost no hidractive and an activa that was brought at 96 for inspection and is the only one here.
there is also 1 3.0L model that use to belong to the main dealer.

LeeDJC · Post by **LeeDJC** » 22 Apr 2007, 09:21

wonderd wrote:BTW, i wish mine was hidractive, only those cars are very rare in israel... as far as i know there is only 2 here, one is activa.

Maybe i could import all the parts and transform mine to activa...

I don't know how the import laws work in Israel, but I expect it would be cheaper (and far far far easier) to buy an Activa here in the UK, and then import it to Israel.

The cost of the Activa components are pretty high (particularly new ones). But good complete Activas are pretty darn cheap over here!

wonderd · Post by **wonderd** » 22 Apr 2007, 10:21

you can"t import cars over 3 years old to israel unless they are over 30 years old.
i thought about buying an activa at the UK, taking it apart there and ship the important parts back home.

Post by **CitroJim** » 22 Apr 2007, 12:58

wonderd wrote:i thought about buying an activa at the UK, taking it apart there and ship the important parts back home.

Now there is a project I like the sound of

Doable certainly, but a heck of a lot of work although mainly jaut a plumbers nightmare and a bit of electrical work.

AndersDK · Post by **AndersDK** » 22 Apr 2007, 13:10

wonderd wrote:Yes, thank you, i got it now.
I called the dealer and he will order me the right spheres for my xantia.

Last Q: what are comfort spheres? will they fit my car?

Comfort spheres do exactly as their designation depicts : increases ride comfort.
Its done by using a bit larger center hole.
This sphere type will get your Xantia closer to the old style "Citroen flying carpet" ride known from the good old days.

These days all car makers are focused on drivng safety, which invariably means a stiffer suspension to make the car as safe as possible at speeds.
This does not mean that the car will be unsafe when its softer. It simply means it will react like an earlier model, i.e. it will lean more when cornering at speed.
Its all about compromising between ride comfort and vehicle stability at speeds. You can not have both a comfortable ride and a stiff suspension. You will have to choose either one.

The hydractive system overcomes this problem to a certain extent by switching between soft and stiff suspension. In other words you may say the sphere types are switched during drive - without you have to go out unwinding and replacing the spheres while you are driving 8)

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xantia spheres pressure changes

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