C5 H3+ front suspension travel

309B6D

309B6D

Member
VIP Paid Subscriber
Fellow Frogger
Tadpole
Joined
Jul 30, 2020
Messages
105
Location
Northland NZ
My "new" C5 (2010) has traveled less than 50k. It has the look of a well cared-for car.
A service/belt change and check for problems showed a rear sphere was needed.
A couple of weeks later a roadworthy check showed that control arm bushes were showing signs of age.
New arms have been fitted and they improved general steering response. Sharper turn-in and less steering adjustment is required during cornering. Excellent result.

Having been over the same road quite a few times in the past month (to and from the best Citroen garage) and not noticed any problems. I was surprised to have the front left suspension compress to give a very solid thump to the body. It happened on my return trip - 4 times.
I have tried the car out on a few occasions and apart from a little less rebound damping than a good spring/shock car I was impressed with the way the C5 worked.
On this last trip two of the bumps were on the left only. A raised lateral edge at a bridge was about 50mm high with a patch forming about a 30 - 40 degree ramp up from the road surface to the lip. A 50kph approach had the left wheel thump up with an abrupt halt at the top of its travel. The right side had a smaller step and it handled the bump with no drama.
One bridge had about 25mm lip right across and the bang was violent enough that I couldn't tell if it was both sides or just the left. The fourth event was a short sharp depression on the road edge. The wheel dropped down and the thumped hard on the far side of the half metre long dip. Bang again as it hit the end of its travel.
There seemed to be no compression resistance, or not enough to stop the travel.
The impacts were enough to make me wonder if my new wheel alignment is now altered.


With the engine idling to keep the system pressurised I pushed down on each front corner. Maybe the left side is slightly softer and recovery from the bounce is slightly slower. But only slightly.

Being a newbie to the wonderful world of Hydractive 3+ I cannot quite understand why this is happening.
Are short shape bumps not managed very well by H3+ ?
Is it a failing sphere, or are they OK until they have an obvious failure?
Is the hydraulic pump not giving the required pressure to the system?
Is there anything that a reputable Citroen specialist might have done during the control arms replacement that could have prevoked deterioration in an ageing sphere.

I am at the point where I am wondering about having all 7 spheres replaced. Then I would know what the baseline performance was and know that was all I could expect.

Other than these problems I love the C5 Exclusive with 2.0 diesel (163bhp) RHH. I bought it for a very reasonable price and it is so pleasant to be in that the poor Peugeot 309 SRi hasn't moved for over a month.

I have searched the subject but have not found many results. I think most of the knowledge on C5 X7 must be known by this forum. They seem popular with froggers over there in Australia.
Hopefully someone can enlighten me about this problem.

Thanks to all the members for their contributions to this site. I really enjoy my frequent visits to here.

Bryan
 
You are already half way there I believe. The spheres rely on a defined volume of nitrogen at specified pressures to work at their optimum balance of suppleness and travel. The front spheres require more gas pressure than the rear ones as they carry more weight. Think about the spheres as coil springs made of different thickness wire. You state a rear sphere has already been replaced, so it is likely another has reached its end of life state too. There has been considerable discussion on this site re the wheel/tyre selection as well with the concensus being the larger diameter lower profile tyres actually reduce the comfort level. If the car is doing its self levelling act you will not have a hydraulic pump issue. Maybe it is a case of your becoming more familiar with the car as well as some performance reduction as the result of sphere ageing. A simple test is to push down on each corner of the car and see if you can feel a reduced travel when compared with the other side, as you have already done. Sphere health can be determined by removal and placing on a special pressure tester. If found below the recommended pressure replacement should be considered. Spheres are not interchangeable, eg fronts swapped for rears. Fronts carry greater pressure and the Hydractive spheres that control ride stiffness do not have built in damper valves, thus the specified location ( effectively the work they do ) is what determines the individual sphere's loaded working pressure, even though they might all LOOK identical. These are referred to as "saucer" spheres because of their flattened shape when compared with previous generations of sphere ( saucer spheres are always silver in colour, the previous generations being military green or the first generation being black ). Look closely at the top of the spheres and you will see the charging dimple, a stamped chevron indicating a factory sphere and a 2 digit number that will indicate its initial fill working pressure in BAR ... atmospheres. Say, off the top of my head a pressure of 57 bar. The working pressure of the hydraulic system is considerable .... spheres cannot be twisted off without complete depressurisation of the stored pressure first, in theory achieved via the onboard computer's instructions. Suspension bush replacement on X7 fronts has been discussed on this site also and IIRC there are two types of lower control arms.
Your local Citroen specialist should be able to advise, IF he has hydropneumatic experience.
Really the only accurate way to discover sphere charge/health is via a pressure tester, seat of the pants measurement as you describe above is not really viable for diagnosis. The other consideration re sphere life is the location of the sphere during its service life. Rear spheres live in a cooler environment than the ones mounted ( in sometimes impossible cramped places ) next to the engine.
 
What you are describing doesn't sound like a sphere issue at all to me. When a sphere fails, it loses it's gas and becomes hard. The suspension doesn't travel at all once the pump has brought it to height and it's extremely uncomfortable and bounces when you hit a bump. Also the saucer spheres rarely give trouble and seem to have an extremely long service life - I have a 2006 C5 II here with over 400,000 kms on it and the spheres seem fine.

What you are describing sounds more like an issue with a bump stop. The suspension should travel to a certain point solely on the hydraulic, then engage with a compressible bump stop. If the bump stop is no longer there, the travel will continue until there is a harsh metal to metal contact with will result in a jarring when hitting larger bumps.

The fact that you can push the left down and it feels soft means that the sphere hasn't failed. I frankly quite surprised that you needed a rear sphere replaced at only 50,000 kms - and my first thought is to doubt the mechanic's diagnosis. The control arm wear could indicate that the suspension has had some hard work and that may have included the bump stops. That would be where I would start investigating. I think that if you replaced all the spheres the only thing you would notice different is the thickness of you wallet.

A small disclaimer - I have no direct experience of the X7. I have quite a bit of experience with the Mark 1 and Mark 2 C5s and with Xantias. The X7 front suspension is different from the earlier cars, but still has the same basic function.
 
Interesting. I was under the X7 the other day and found the rear bump stop disintegrated on one side, missing on the other. I can't remember any bump that might have done it.
 
If the bump stops are the same material as fitted to the rear of the first shape C5 it is akin to chocolate cake.
 
Sponge cake type foam material on C5 S1 haven't checked them since replacing at 250k I'm sure they should last 100k. If the X5 are disintegrated my guess same material?
 
Interesting. A quick search on Ebay shows the vast majority of offerings are a different design and made of white coloured material. The "chocolate cake" variety are flesh coloured beige colour. Doesn't help our NZ friend though as his is an X7..... but food for thought and research.
 
The rear bush on the front LCAs is not very robust and Citroen does not supply it separately. You can buy aftermarket bushes though. There is also a bush in the bottom of the front upright that wears and sometimes pops out. So inspect that.
Check the anti-roll bar has not shifted or broken a mount.
Is the ride height correct? The pump adds and removes fluid to adjust the height using an electronic sensor with a manual link at each end. If the car is too low, you will hit the stops sooner for a given bump. You could try the bump at the next setting up, be remember the lowest and highest are for service and wheel changing, not driving.
You should firstly check it has the correct spheres in the correct location. See the data for the damper and static pressure here:
https://www.aussiefrogs.com/forum/index.php?threads/c5-x7-suspension.149304/post-1802282
Spheres last a long time, but can sometimes go flat or be ruptured if overloaded. It is best to remove them for testing.
The H3+ stiffness regulation, middle spheres, do not have a damper as that is part of the block they mount to. If one of these has failed it will fill with LDS and you would see a poor ride, probably not bottoming out.
Remember the suspension uses LDS and the brakes are DOT 4 brake fluid. Be sure that nobody mixes them up!
 
Last edited:
Thanks for all the detailed responses. The time taken to go into such detail is much appreciated.

I contacted the workshop this morning and after describing the symptoms to him he is quite sure that it will only require a ride height adjustment.
The question and explanation from David S about ride height appears to have been right on target.

I am taking in back on the Wednesday after Easter, so I will post a comment about the result after testing it out on my way back home.
 
Our David S is a marvel. He is exacting in his descriptions, so this site has supplied a range of correspondence that ranges from the theory to the practical. Aussiefrogs triumphs again because of the varied contributions. It sounds like the Kiwi workshop might be experienced in upsy downsy.
 
You have checked the level of fluid? Put the car in the lowest setting in order to undo the cap, rotate it gently with a oil filter wrench use one with a strap not a metal ring. Top up if needed. Re tighten the cap gently.
 
@FLIPPER MAN:
Youre advise is a little bit strange, why firt put the car in the lowest position? Because the the pressure is higher than if you put the car in the highest position, and also the cap should be removed by hand!!
An other question, what do you mean by "top it up"?
There is a special procedure to check the LDS level, because if you top it up like you said, the change that the tank wil burst is very likely!
The best way is to use the diagbox, and if it's not possible, put the car in the lowest position and check if you see that the LDS is just tatching the bottom.
Greetings,
Kees.
 
The ride height was adjusted. Front sensor was out after replacing the lower arms and rear sensor was adjusted too.
There is a lot more distance between the top of the tyre and the arch now.
The trip home covered the same route that had showed the problems. We were laughing at how easily the H3+ absorbed the bad bumps.

After buying the car there was a bounce and wriggle from the back which I put down to a Citroen quirk. Now on in similar situations there is a very balanced feel between front and rear. Rebound feels more controlled. The car rides level over bumps and dips with no wallowing.

Now that I have driven a well adjusted Hydactive 3+ car I am left feeling sad that Citroen dropped the system after it had reached such a high level of sophistication.
 
Good to hear .. the system works when it is set to the original settings and all is ship shape.
Now you have set me wondering about HOW and WHY all the heights got "out of kilter" ... one has to assume human intervention by someone not able to deal with the technology.
 
I suspect the guy on the next post ( about his previous generation C5 wagon ) has similar issues.
 
HOW and WHY
The front ride height would have been incorrect with new arms and bushes. It would be sitting higher with firm bushes, but H3+ with badly adjusted sensor would have over corrected the height.
Apologies were given. I assumed mechanic had slackened off the sensor clamp during arm replacement to make it easier to get the ARB out of the way. Then forgotten to tighten it properly.
The rear was out from previous ownership. Papers show PO had a detailed alignment done at about 40thou km.
The long plastic skirt on the left sill was loose at the rear. Perhaps he had backed over something and crunched something that forced the sensor out of adjustment. The location of the alignment company would not see many C5s so who knows how correct their work was.
 
Thanks for the back story. It is the lack of knowledge that sees me even take wheels off before visiting a tyre shop. The lack of knowledge about how the system actually WORKS and the time delays involved in the car getting itself back to normal ride height after being lifted may have been the reason for the damage to the plastic skirt. The lack of on the ground knowledge and plain incorrect stories to non technical owners has been often discussed on AF.
I find the Facebook groups are fraught with NON knowledge and useless so called advice.
Viva Aussiefrogs for sharing the knowledge. I am often surprised by the overseas enquiries made to Aussiefrogs. We have had people onsite from Iran and Ireland lately.
Sounds like the C5 magic will continue to amuse and amaze. Knowledge is power, and in OZ many service industry people would never have seen a Citroen .. ever. "Do they still make them ?" is a common question, let alone finding someone who is prepared to actually work on the things. Sadly the knowledge base is shrinking as we rusted on owners age and the modern cars are not hydraulically suspended.
 
You must log in or register to reply here.
Top