C5 X7 harsh front suspension

[wfdTamar]

When I got my C5 I had to replace the front left sphere (it leaked). From memory it needed 2 litres of LDS. It's got the 19" wheels. 146,000 km.

When the engine is on and suspension is set in Normal, if I try to push down on the car corners the front is quite firm, the rear quite soft. The front suspension has never felt like what I was expecting (comfortable), most notable when going over those small speed bumps (the ones about 100mm high). No matter how slowly I go over them, it gives quite a bump from the front wheels (the rear seems fine). I have no idea if that's normal, or there's something wrong with my particular car.

Could other spheres be faulty? Is it worth changing the LDS fluid? Is there any kind of suspension diagnosis guide?

[aerodynamica]

It does sound like one or more spheres at the front has failed. There are 3 at the front: one at each side and a single middle sphere that is connected to the sides. This can only be seen easily from underneath.

If the car is at the right height and it's stiff to push it is likely caused by a dead sphere.

The soft ride is achieved by riding on all 3 spheres together. When the hydractive suspension wants to stiffen the ride for corners or to control undulating the centre sphere is quickly switched out of circuit to ride only on the 2 L&R spheres that give a stiffer ride.

The fluid connects everything but the spring is done by the gas Pressurised in the sphere - sealed in by a movable diaphragm. These can fail with age and the gas can then escape and this loses the movement available to the suspension.

Changing the 2 L&R spheres isn't very difficult but unfortunately the middle sphere is very inaccessible and needs the front subframe lowered to access. They are also very tightly screwed on. I had to get a garage to replace my middle one.

[wfdTamar]

Is the amount of bounce when pushing down on the body (motor running) similar front and back?

[GiveMeABreak]

The X7 has long-life spheres however a replacement sphere should not have failed unless it was a non-original sphere. These are NOT supposed to be re-gassed like the old green LHM spheres. If the replacement sphere was an aftermarket one, then I would put the blame there. Originals are expensive, but they are designed to last. The ride on mine was perfect after 75k miles, although my front right strut developed a 'weep' so had to be replaced.

Also be aware that the sphere has 3 prongs built into the upper part of the sphere that are designed to rupture the membranes if there is an over-pressure situation to avoid explosive damage. If the ride is harsh, the sphere may have been over=pressured and ruptured, so you will be riding on tyre pressure and strut fluid with very little springing on that side. That can be caused by over-filling the LDS reservoir (levels should always be checked on the lowest suspension setting or with the system depressurised) and be between the 'a' & 'b' mark.

[wfdTamar]

It was 3 years ago. It was about £180 (including shipping to Australia). Pretty sure it was genuine. I'm suspecting something other than that sphere - if what I'm feeling is not normal. Because this is the only one I've driven I don't know.

[GiveMeABreak]

As Graeme has mentioned, normal comfort mode utilises all 7 spheres. Sport mode cuts out the centre 3, leaving only the corners. If you have a bad front centre sphere then it will be like riding in sport mode at the front, so definitely a lot firmer. Diagbox live data on the suspension can tell you if the electrovalves are opening and closing on the hydraulic blocks.

Try bleeding the system first though as it's free:

1. LDS cap off.
2. Start the engine.
3. Setting suspension in high position.
4. Setting suspension in low position.
5. Turn the steering wheel slowly lock to lock (do not hold the steering wheel at the lock limit!).
6. Return steering wheel to centre position.
7. Engine off.
8. Wait for all the bubbles to disappear.
9. Check fluid is between the marks in the procedure.
10 Repeat as necessary.
11. Raise vehicle to normal height.
12. LDS cap back on.

[wfdTamar]

It does feel different in the two modes. I did bleed it when I replaced the sphere, but worth a try again.

7 spheres? One at each corner, 1 centre front. Where are the other 2? Inner rear?

[GiveMeABreak]

The other 2 are at the rear centre. They are housed under a protective shield and connected to the rear hydraulic block.

(10) Rear suspension cylinder (right).
(11) Rear suspension sphere (right).
(12) Rear stiffener regulator accumulator (right).
(13) Rear firmness regulator.
(14) Rear stiffener regulator accumulator (left).
(15) Rear suspension sphere (left).
(16) Rear suspension cylinder (left).

[wfdTamar]

Is it worth replacing all the LDS given the possible problem and km's the car has done? Does the LDS lose its qualities as it ages? What's the capacity of the system (I think I saw 5 litres mentioned somewhere)?

[GiveMeABreak]

LDS Capacity 5.3 litres.

Hard to say whether LDS alone would result in a harsh ride. If the ride firmness is noticed from switching from comfort to sport mode then that would indicate the centre spheres are at least cutting in and out. Try bleeding first.

[wfdTamar]

Still trying to work out how to diagnose what's faulty. I've had a prod of another car and it felt softer on the front corners (engine running) than mine. On mine, both front corners feel the same (stiffer than the other car). Bleeding made no difference.

'Diagbox live data on the suspension can tell you if the electrovalves are opening and closing on the hydraulic blocks.'

What does the above mean, or tell you? Is it of help in diagnosing what's wrong? I have reasonable DIY knowledge of cars, but not of the things peculiar to Citroens.

[GiveMeABreak]

That basically means Diagbox can provide live testing of the electrovalves in the BHI and also the hydraulic blocks (front and rear), the latter to confirm whether hard or soft mode is being engaged through the opening and closing of the electrovalves.

So I would be looking at checking on whether you had the correct part numbers for the sphere (s) when you last replaced it / them as there are different sphere pressures depending on front / rear and corner / accumulator spheres etc. as well as for tourer and saloon models and lastly engine type. If you have the incorrect sphere pressures that can make a difference.

[wfdTamar]

I only replaced the front left sphere and that was 3 years ago, so I don't have records of it. It has the Citroen chevrons embossed on it (but I'm sure that doesn't mean anything) and some numbers, but they're not as distinct as on the right one (presumably an original). Virtually unreadable, but I think I could decipher the ones on the right one. (pics attached)

Is there a good source for them in the UK? I'm coming over next (northern) summer so could get any I need then.

Not sure if I'm paid up enough to get part numbers (and How To's), but could I get the front corner and centre sphere part numbers and a How To for changing the centre sphere? Thanks.

VIN: VF7**************[VIN obfuscated, can be read by forum staff]

[GiveMeABreak]

You can upgrade your membership anytime Bill (£10 min), using this link: donate, which will automatically upgrade you, then request any part numbers on this thread:

viewtopic.php?p=685750#p685750

The sphere IDs in the middle are correct (MB 45) which indicates the suspension ID number and the pressure. In this case Front spheres (corner) and 45 Bar pressure which is correct for this engine. However, the markings for the part on the left sphere are hard to make out as the camera light and angle is making it hard to see, but appear etched or worn down. This on the face of it could indicate a re-used sphere.

So may be worth looking at replacing these or grabbing some when you head this way (although I'd order ahead first from your chosen supplier).

[wfdTamar]

How long does the donation cover us for (it doesn't mention it on that page)?

The one with the bad markings (not worn, just badly embossed) is the one I replaced 3 years ago. Hard to get a readable photo with it in the car. That makes is suspect (of not being genuine) but it does have a similar amount of bounce as the other side.

So unfortunately it's the middle one that's most questionable.