Xantia bouncey suspension

alski · Post by **alski** » 26 May 2005, 06:17

Hi there first time on this site hope you can help.
I have a P reg xantia 1.9 TD. Had the front spheres renewed a few months ago. front suspension now feels very bouncey when on undulating road surface ie traffic calming bumps etc. (Feels like a boat in the ocean) I thought it might help to re-pressurise the system but when I undid the pressure regulator release screw I didn't hear any whistle and the front didn't drop. I repressurised the system anyway and the car goes through the full range of movements when operating the height control lever.
I also noticed that the ticking sound occurrs every ten seconds and when I checked the hydraulic reservoir with the engine running and at max height the orange mushroom disc is right at the top of the glass dome and not between the two red rings. there is fluid in the reservoir but only to about half way.
Any suggestions will be gratefully received.
Thanks[:(]

tanto · Post by **tanto** » 26 May 2005, 07:46

after changing the spheres the may be air in the system you will need to do the citaerobics as described below
citaerobics (originaly posted by andersdk on another forum)
After replacement of suspension spheres - or pressure lines - some air will evidently be trapped in the suspension on assembly. Air may also be trapped in the suspension if the pump suction hose leaks. Sometimes leaking spheres also causes "air" in the suspension.
This air is not vented automatically by the system - and must be vented out - to avoid any strange symptoms from the suspension during drive.
Please note - that this procedure does not vent air in the brake lines/calipers - these must be bled manually - as they are dead ends in the system.
Only the closed circuit between HP pump & PR pressure regulator is vented automatically.
To vent the suspension system :
Select neutral on gear selctor - apply handbrakes - have engine idle.
Set the height control selector to the HIGHEST setting - allow time for the height to fully settle - indicated by the regulator clicking calming down to normal again.
Then set the height control selector to the LOWEST setting - allow car to fully sink down on the rubber stops - indicated by a vibration from both front & rear.
Repeat this 5 times - then all air will be vented out.

DoubleChevron · Post by **DoubleChevron** » 26 May 2005, 08:08

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by alski

Hi there first time on this site hope you can help.
I have a P reg xantia 1.9 TD. Had the front spheres renewed a few months ago. front suspension now feels very bouncey when on undulating road surface ie traffic calming bumps etc. (Feels like a boat in the ocean) I thought it might help to re-pressurise the system but when I undid the pressure regulator release screw I didn't hear any whistle and the front didn't drop. I repressurised the system anyway and the car goes through the full range of movements when operating the height control lever.
I also noticed that the ticking sound occurrs every ten seconds and when I checked the hydraulic reservoir with the engine running and at max height the orange mushroom disc is right at the top of the glass dome and not between the two red rings. there is fluid in the reservoir but only to about half way.
Any suggestions will be gratefully received.
Thanks[:(]
<hr height="1" noshade id="quote"></blockquote id="quote">
It shouldn't be bouncy, I wouldn't be surprised if the wrong spheres have been fitted to the front of your car. If you have a sphere pressure tester (or a friend with one) now would be a good time to check the spheres to ensure you haven't be sold flat(ish) spheres.
If you open the regulator bleed screw, all you are doing is exhausting the high pressure reserves in the pump circuit. ie: the pump will not create pressure, and the main accumulator will be exhausted.
However the brake accumulators will still have pressure as will the suspension as they are the other side of the priority valving. To fully depressurise a non hydractive hydraulic Citroen you need to move the height lever to low, open the regulator bleed screw and pump the brake pedal until the brake accumulator is exhausted.
To check the hydraulic fluid level you need to put the car on 'high' then look at the disc and make sure it's between the levels shown.
As your talking several months after the spheres have been changed I seriously doubt there is still air in the suspension circuit. It will self 'bleed' the air out in time.
good luck
Shane L.

Mandrake · Post by **Mandrake** » 26 May 2005, 12:25

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by alski

Hi there first time on this site hope you can help.
I have a P reg xantia 1.9 TD. Had the front spheres renewed a few months ago. front suspension now feels very bouncey when on undulating road surface ie traffic calming bumps etc. (Feels like a boat in the ocean)
<hr height="1" noshade id="quote"></blockquote id="quote">
Ok, first of all, you had the spheres renewed a few months ago - was this "bouncy" problem in evidence immediately after the spheres were replaced, and you're only now wanting to do something about it,
- or has it happened gradually,
- or has it just happened suddenly just recently ?
By renewed do you mean regassed, or do you mean new spheres ? (Genuine Citroen, or if not, what type ?)
The answer to those questions will help steer people in the right direction.
Also you possibly need to better define what you mean by "bouncy" as you might be confusing "bouncy" with "wallowy" which are actually opposite ends of the spectrum.
"Bouncy" is what you'd tend to notice when the spheres are very low in gas, suspension travel will be severely limited (if you press down on the suspension it will feel very stiff) and can also be caused by the ride height being too low or too high, but in particular too high tends to give a bouncy ride.
Does the ride height look normal, and does the height corrector adjust the height automatically to the correct height when weight is removed or added ? (Get someone to sit on the front with the bonnet open while the engine idles, and watch from the side as they get on and off to make sure it corrects reliably back to the same height)
On the other hand a "wallowy" ride where it feels like you're floating along on a boat tends to be caused by too high a gas pressure and/or a damper valve calibrated too soft, which would generally only be the case if the wrong spheres were fitted, and this is only likely if you've noticed the problem ever since they were fitted.
There are also different gas pressures and damper valve holes for different variations of Xantia, and some may not be to everyones liking.
(I find that Citroen often err in the soft floaty direction with their damping, especially on the lower spec'ed models and a bit tighter damping control can give a lot better handling with minimal loss in ride IMHO...)
Refer to the following table:
http://www.gsfcarparts.com/downloads/sphere_table.pdf
I notice that the 1.9D and 1.9TD have very different front spheres - 70 bars and 1.65mm for the 1.9D and 55 bars and 1.5mm for the 1.9TD.
Basically the 1.9D version of the front spheres will have a MUCH softer more floaty ride with less damping control, based on looking at those figures.
(Higher pressure in bars = a softer springing rate all other things being equal, while a larger damper bypass hole = softer/less damping control all other things being equal)
It's possible then if your ride has been like this ever since the spheres were changed that you ended up with the spheres for the 1.9D instead of the 1.9TD.
Easy way to tell is to look on the top of the sphere near the bung for a stamped number - if it says 50 or 55 you probably have the right spheres, but if it says 70, you have the wrong spheres and should get them swapped under warranty.
<blockquote id="quote">quote:<hr height="1" noshade id="quote">
I thought it might help to re-pressurise the system but when I undid the pressure regulator release screw I didn't hear any whistle and the front didn't drop.
<hr height="1" noshade id="quote"></blockquote id="quote">
Unscrewing the pressure release valve on the regulator will only depressurize the main pressure supply, not the suspension, espeically if your car has anti-sink valves.
You should have heard a whistle though. It's possible your accumulator sphere is dead. To find out, follow the procedure I mentioned here:
http://www.andyspares.com/discussionfor ... hichpage=1
<blockquote id="quote">quote:<hr height="1" noshade id="quote">
I repressurised the system anyway and the car goes through the full range of movements when operating the height control lever.
I also noticed that the ticking sound occurrs every ten seconds
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This is consistent with a dead or low pressure accumulator sphere
<blockquote id="quote">quote:<hr height="1" noshade id="quote">
and when I checked the hydraulic reservoir with the engine running and at max height the orange mushroom disc is right at the top of the glass dome and not between the two red rings. there is fluid in the reservoir but only to about half way.
Any suggestions will be gratefully received.
Thanks[:(]
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Make sure the indicator disk isnt stuck. They have a tendency to get stuck. Otherwise you have a bit too much oil in the tank, try carefully syphoning some out until the disc is between the two lines with the suspension right up. (and engine running)
The main problem with having too much oil in the system is that if the car is fully depressurized, most of the oil returns to the tank and it may overflow through the top of the tank.
Edit: Opps, one other thing that I forgot to consider, is whether your car is Hydractive 2 or standard suspension ? My suggestions assume that it's not Hydractive 2.
Good luck.
Regards,
Simon

jeremy · Post by **jeremy** » 26 May 2005, 13:48

The correct procedure for checking the LHM level is to raise the car fully and then check the level. Fluid is pumped into the suspension cylinders and so when you drop the car to normal height the level in the reservoir rises - giving the impression of overfilling. In fact if at normal height the indicator is between the 2 marks you need to investigate and top up!
Overfilling is not generally important - just messy.
Jeremy

citronut · Post by **citronut** » 26 May 2005, 14:19

perhaps there is nout wrong with front you might find rears need changing,because if fronts are replaced and rear was firm but not hard yet,the front will have movment as it should and the rear will not,so it gives impretion the front is to soft,also fluid level if checked on level ground with susp/wright up and float is above red lines it is over filled,the only prob this is you may have fluid overflowing from top of tank,which just makes a mess regards malcolm

alski · Post by **alski** » 27 May 2005, 05:38

Thanks for all the input you guys.
To clarify a few points, The spheres were replaced not regassed but I don't think they are Citroen ones (no dimples). I have looked for a number but it is underneath and not visible will have to try with a mirror.
There is plenty of movement when I press down on the suspension and it is more of a wallow up and down when moving.
The height adjuster seems to be working correctly when weight is added and removed.
The orange disc stays at the top of the glass at whatever height setting and the reservoir looks nowhere near full.
I carry out checks for sticky indicator disk and dead accumulator sphere and see what I find.
Thanks Al.

Mandrake · Post by **Mandrake** » 27 May 2005, 06:28

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by alski

Thanks for all the input you guys.
To clarify a few points, The spheres were replaced not regassed but I don't think they are Citroen ones (no dimples).
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Not all Citroen spheres have the 3 dimples. In fact a lot don't, as according to someone else on the forum here the 3 dimples just means its a multi-membrane sphere.
<blockquote id="quote">quote:<hr height="1" noshade id="quote">
I have looked for a number but it is underneath and not visible will have to try with a mirror.
<hr height="1" noshade id="quote"></blockquote id="quote">
Yes, it can be hard to see while on the car. You might need a torch and a small mirror, and also a wet rag to wipe off any dirt on the sphere. Try checking the sphere on the other side, it might be the right way up to read it...
<blockquote id="quote">quote:<hr height="1" noshade id="quote">
There is plenty of movement when I press down on the suspension and it is more of a wallow up and down when moving.
<hr height="1" noshade id="quote"></blockquote id="quote">
Ok, if its very soft to press down and seems to wallow on the road, I'd be betting that the gas pressure is too high and or damper hole too large - eg quite possibly the 70 bar spheres are fitted instead of 50/55.
<blockquote id="quote">quote:<hr height="1" noshade id="quote">
The height adjuster seems to be working correctly when weight is added and removed.
<hr height="1" noshade id="quote"></blockquote id="quote">
Good...
<blockquote id="quote">quote:<hr height="1" noshade id="quote">
The orange disc stays at the top of the glass at whatever height setting and the reservoir looks nowhere near full.
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Ok, just be aware that when the orange disc is at the top it does NOT mean the tank is full. Far from it, in fact it will probably be only about 1/4 full when the guage indicates the level is correct.
This is because the level check is done with the suspension fully up - which means the maximum amount of oil has gone into the the suspension spheres, and the minimum amount is left in the reserve tank.
The reason for the level being checked with the suspension right up is because (roughly) the same amount of oil will be in the suspension spheres regardless of whether the spheres are well gassed or not, giving a reading that is consistent regardless of the state of the spheres.
If the test was done at normal height, a car with suspension spheres that were low in gas would use more oil from the tank, leaving the oil level in the reserve tank lower. If you then decided to top it up to the "correct" level there would in fact be too much oil, as when the suspension depressurized more oil would come back to the tank than it would if the spheres were correctly gassed.
I bet you'll find if you let the suspension fully down that the actual oil level in the tank is now dangerously close to the top [:D]
Regards,
Simon

citronut · Post by **citronut** » 27 May 2005, 13:21

when on high the susp/rams take most of the fluid,spheres only take any quantity of fluid wnen gas is low or non existant,because the blader in the sphere colapses,i have taken spheres of my customers car that are completly shot and you get a high presure jet of LHM come out of sphere,and usuly tank level is only low if you have a leak,also what simon said about tank level is mostly corect reards malcolm

alski · Post by **alski** » 28 May 2005, 03:38

How do I check if the indicator disc is sticking?
I had a look at it but it looks like it might be a sealed unit and I didn't want to damage anything by being too heavy handed.
Regards Al.

Mandrake · Post by **Mandrake** » 28 May 2005, 07:45

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by citronut

when on high the susp/rams take most of the fluid,spheres only take any quantity of fluid wnen gas is low or non existant
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I beg to differ here. You can work out how much volume the oil will displace from boyles law.
For example take a 30 bar 400cc sphere from the rear of a Xantia - setting the suspension right up will increase the oil pressure to about 170 bars, which will also compress the gas volume to a pressure of 170 bars. This is a compression ratio of 5.7, which means that the volume of gas will shrink to 1/5.7 of the original 400cc or about 70cc, meaning that 330cc of oil will be in the sphere, in other words over 80% of the sphere is now full of oil and the diaphram is fairly close to the top.
Although I don't know the diameter and stroke of the hydraulic ram to work it out, I'm guessing that this is more oil than the ram displaces, so its definately very significant.
Another example - front spheres of a Xantia, 50 bars and 450cc (the 3 dimple version of the sphere) you get:
170/50 = 3.4, 450/3.4 = gas compressed to 132 cc, oil = 318 cc or 70%, so even in this case 70% of the sphere is full of oil.
Because even normally gassed spheres like this allow 70 - 80% of the sphere to be filled with oil when the suspension is fully up, the difference in oil displacement from the reserve tank during an oil level check is quite small whether the sphere is gassed or very low in gas, (or has a punctured diaphram) - 70cc for a rear sphere and 132cc for a front sphere.
If the test were to be done at normal height there is now a much greater difference between the normal amount of oil going into the sphere and how much would go into a low gas/punctured diaphram sphere, hence the reason the check is done in the fully pressurized state...
Regards,
Simon

citronut · Post by **citronut** » 28 May 2005, 14:54

in my experiance 99% of the time when hydraulic citroens are low on fluid it is because there is or has been a fluid leak,quite often this only a very slight leak and the reason for checking level on high is because citroen have calibrated the indicator,although there is more fluid taken up by the system when shperes are at a diferant level gas,also i have never found a float stuck it is usuly to high due to to much fluid,as some said when float at top of bulb with susp on high there may only be half tank of fluid,it is likly it will only overfill when susp gose right down regards malcolm

alexx · Post by **alexx** » 29 May 2005, 01:22

Each suspension cylinder displaces only 50-80 ccm between low and high, depending on the model.
For example, rear suspension cylinder diameter is 35, 38 or 41 mm on Xantia, and its stroke is about 6 cm

Mandrake · Post by **Mandrake** » 29 May 2005, 04:43

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by alexx

Each suspension cylinder displaces only 50-80 ccm between low and high, depending on the model.
For example, rear suspension cylinder diameter is 35, 38 or 41 mm on Xantia, and its stroke is about 6 cm
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Thanks for the confirmation. That means when the height is set right up most of the oil goes into the spheres not the rams, which is what I always thought...
The relative cc capacity of the rams and the spheres is actually an important key to the success of the hydraulic suspension IMHO - unlike normal springs where the full travel of the suspension is equal to the full travel of the springing medium, the full (dynamic) travel of the suspension is only a small percentage of the total available diaphram travel in the sphere - under 20% by the look of it, for a given height corrector load correction. This improves linearity a lot.
When static load is added and the height corrector corrects the height, the "set point" of the diaphram in the sphere moves up, gas pressure increases, and springing stiffness increases, but linearity stays good as the total travel of the suspension is still less than 20% of the available movement of the diaphram, its just a bit further up in the sphere.
Of course if the gas pressure is low or the load very heavy and it gets near the top of the sphere this linearity is defeated and the suspension has reached its limits.
By the way, do you know which models use the 3 different diameter pistons at the back you describe ? For example does the estate (which normally has 40 bar spheres) have a larger diameter piston than the equivilent saloon ? (which normally has 30 bars)
Regards,
Simon

alexx · Post by **alexx** » 29 May 2005, 15:34

Saloons up to '96 had 35mm rear cylinders, like BX, GS etc. Newer models have 38mm cylinders (saloon) or 40mm (estate - not 41mm as I wrote in previous post)
Front cylinders on older models are 22mm, but their stroke is equal to front suspension travel (about 14 cm). I believe that they are also a bit larger on post '96 models, but don't have info about that.