Stiff suspension after spheres regassing - C5 X7

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GolfMk1Vr6
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Re: Stiff suspension after spheres regassing - C5 X7

Post by GolfMk1Vr6 »

Yesterday i took the car for a drive and it feeled a bit softer. I did the bleeding method twice and somehow it's 10-20% softer but still stiffer than before.

If air gets into the circuit somehow, the suspension wouldn't be more softer because air is compressible?
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Re: Stiff suspension after spheres regassing - C5 X7

Post by Kees »

@GolfMk1Vr6:
It has no use to think about air in the system. You bleed it a few times, so don't worry, there's no air in the system.
But as i said before all sphere's works together, and the center sphere is for the soft mode/ride.
You regass the corner sphere's, because they lose pressure, so why didn't the center sphere is also lose the pressure?
Make it yourself easy, and regas/replace the center sphere.
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GiveMeABreak
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Re: Stiff suspension after spheres regassing - C5 X7

Post by GiveMeABreak »

GolfMk1Vr6 wrote: 26 Apr 2024, 19:21 Yesterday i took the car for a drive and it feeled a bit softer. I did the bleeding method twice and somehow it's 10-20% softer but still stiffer than before.

If air gets into the circuit somehow, the suspension wouldn't be more softer because air is compressible?
No, because air is compressible, but LDS fluid is not. So this causes locks in the system - just like air in the braking system which means the fluid is not getting to where it should and pressing the brake pedal causes spongey soft brakes that don't work.

If the ride is the same level of hardness at the front and rear then the centre sphere you didn't do wouldn't cause that. If you didn't change the front centre sphere for example, then you would get a firmer ride at the front, but the rear would still be normal as it's riding on 4 spheres.

As you know these saucer spheres are not really intended for re-gassing, so I can't comment on that, but other issues can be:

Incorrect sphere pressures
Airlocks in the system
Incorrect height settings
Faulty hydraulic stiffness blocks
BHI
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Re: Stiff suspension after spheres regassing - C5 X7

Post by lcwin »

Change the front center sphere .
I hope you did not put the rear sphere to the front as the damping is different . Never over inflate your sphere more than 20% as it will affect the position of membrane inside the sphere which should be about halfway inside. Anything more can cause rapture or reduced suspension travel . The older round sphere can be inflated more. Do a simple bounce with car locked for 30 min or more and then start car and do it again on all 4 sides. It should be quite easy to push down with the engine On .
Finally sphere can rapture after refilling.the bounce test will tell you. I usually just set car to lowest position,jack up side slightly and change sphere unless I am doing center sphere. I will use lexia to depressurize if doing center sphere. After its change just set car back to normal position.
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Re: Stiff suspension after spheres regassing - C5 X7

Post by vallium »

GiveMeABreak wrote: 25 Apr 2024, 09:459. Check fluid is between the 'a' & 'b' marks in the picture below.

Image


If you have fluid between A & B marks when low and then completely depressurise the system with diagbox tank will overflow. Ask me how I know :)
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Re: Stiff suspension after spheres regassing - C5 X7

Post by GiveMeABreak »

Not a complete disaster though, and for normal use it's fine for the reasons I've said - as in just topping up when you haven't depressurised the system manually or with Diagbox. But yes, 100% agree that if you are planning to depressurise in future for sphere changes or other maintenance, then I'd either manually depressurise the front or the back independently using the valves screws which should reduce any fluid loss - otherwise make sure you've plenty of rags to soak op any spillage as you don't want this flowing onto the BHI or the Pump.
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verdi
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Re: Stiff suspension after spheres regassing - C5 X7

Post by verdi »

Hi Marc
Regarding the Hydraulic liquid - Does a brown/rusty color of the LDS before bleeding, means air in the system? I dont see any bubbles.
after a bleeding the LDS became clear.
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Re: Stiff suspension after spheres regassing - C5 X7

Post by GiveMeABreak »

LDS is a reddish / brown colour. The bubbles are more like a 'fizzing'.

When you have it on the lowest setting during the bleeding process, when you get to the turning of the steering wheel part, I would actually turn the steering wheel left to right about 8 times, slowly, just to give the system time to work out any air. If that has been done and the suspension it still hard, then it has to be the spheres (incorrect gas pressure or no gas) which will mean it is only the fluid pushing against a membrane with little or no gas and therefore no compression, resulting in a hard ride. In this situation the vehicle will only be suspended form the small amount of gas in the sphere (if there is any) and the tyres.

As I've said, these spheres are not supposed to be re-pressurised and they have spikes inside the gas chamber to puncture the membranes in the event of over-pressurisation to avoid explosion of the sphere casing.

If the re-gassing operation has failed, has leaked or was over-pressurised then this can be the reason. I suppose you have to ask the question: is the car now worse than it was before you had the spheres 're-pressurised'? If so I think that is where the issue lies.

Personally, I would only fit new spheres to avoid all these issues.
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Re: Stiff suspension after spheres regassing - C5 X7

Post by GolfMk1Vr6 »

Hi!

I don't have any update of my problem, other than the fact that sometimes is soft as it should be, especially after a longer trip it became enjoyable again. After few days of resting it became stiff again.

If the front center sphere is the problem, should it behave like that?

- it might be a problem with the front/ rear rods from the position sensors? The rear one was rusty but was cleaned by my mechanic, the front one not.

- if the car sits for more days and after that it became stiff again, should be a problem with the air locks in the system?

I'm pretty tired of it... Thank you!
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Re: Stiff suspension after spheres regassing - C5 X7

Post by GiveMeABreak »

It won't be a problem with the centre sphere itself - that can't simply work one minute and not the next.

Bear in mind that the system is designed to read the roads and other input from the vehicle's sensors including speed, steering wheel angle, road conditions etc. and adjust the suspension accordingly - so are you sure this is not just the Sport mode kicking in and out as intended...

The only other thing I can think of at present with the info you have provided is the front stiffness regulator to which the centre sphere is attached. This block is responsible for the firmness setting at the front.

When in comfort setting all 7 spheres are in play, when it switches to sport mode the front centre and 2 rear centre spheres switch out so that the vehicle is only riding on the 4 corners spheres which gives the firmer ride.

So on motorway driving on good roads, comfort mode will be more persistent until the road surface becomes more rough when you'll find sports mode kicks in automatically as needed.

So obviously without understanding one's definition of a 'hard' ride it could be different to somebody else's perception. If you live in a rural area like I do, my X7 was firmer a lot of the time due to the road conditions and was almost always reported as poor roads in Diagbox when looking at the live data.
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Re: Stiff suspension after spheres regassing - C5 X7

Post by Kees »

I aree with Marc.
Inside the stiffness regulator is an valve, normally is this open, and gives a smooth ride, the BHI provides a 12V for stiff mode.
But when you start the car, the system check the coil (stiffness mode) once and then release the valve.
You said, if you not drive the car for a few days he stays stiffer.
I would check before you ride, when you unlock the car do you hear the h.d. pomp and check if the car raised to normal position, this should be around 73 cm from the ground to the fender.
Also check the corners how it feel, then raise the car, and put it back in the normal position, and check again how it feels.
About your question for the chisel, it must just be long enough, around 25 cm.
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Kees.
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Re: Stiff suspension after spheres regassing - C5 X7

Post by Kees »

@GOLFMK:
Maybe, just maybe......
I was thinking that there is a possibility that the pressure inside the center sphere has influence on the release of the valve.
Normally is the pressure in all 3 sphere's the same in soft mode.
But you mentioned, that after a few days not riding with the car he remain stiff for a longer time.
When you park the car the pressure change slowly between the center and corner sphere's.
Maybe it's b.s.
I wonder how Marc thinking of this theory.
And also as i mentioned before, if the pressure is going low in the corner sphere's, then also is the center sphere not good anymore.
So regass or replace this one.
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Re: Stiff suspension after spheres regassing - C5 X7

Post by GiveMeABreak »

My thoughts:

The gas pressure cannot transfer anywhere (unless the membrane or sphere is ruptured) - it is sealed inside the membranes. We already know the LDS is a fluid which cannot be compressed, so the only thing that can affect the 'springing' operation of the LDS fluid compressing against the membrane with the gas inside is an air lock in the system, low gas inside the sphere, or a sticking hydraulic block valve (or a faulty BHI of course which we don't suspect as the vehicle is raising and lowering properly and the suspension laws are hard-coded in the software).


... or of course the perception of what a hard ride is, or that the system is working as it should and the roads or road conditions are causing Sport mode to engage more frequently.
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Re: Stiff suspension after spheres regassing - C5 X7

Post by Kees »

Marc,
I mean about the pressure, when the sphere's are older like more then 10 years the initial pressure is lower then original.
For example, the front corner sphere's are around 30/35 bar instead of 50 bar.
And so if this is the case, you can assume that also the center sphere is less than the original 70 bar.
I know, some people say "they don't lose pressure" because of the new type of membrane, but each type of membrane wil lose some pressure over time.
Also Citroen advise to replace the sphere's after 10 year.
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Re: Stiff suspension after spheres regassing - C5 X7

Post by GiveMeABreak »

Ok, so yes these have multi-layer diaphragms so don't suffer like the old LHM spheres and yes, they are supposed to give them an unlimited life, but mine were ok after 11 years - but if you opt for new original spheres and find no difference, it's a bit of a waste of money. A hard one this (literally)!
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