Citroen C5 Hydractive Suspension Issue

[rusty-pie]

Few weeks ago I have purchased a Citroen C5 Tourer 2.0 HDI 160 Exclusive Auto made in January 2010 with around 60000 miles on the clock, equipped with the Hydractive 3+ suspension.

I am very happy with the car, but every time I go over a speed hump or a steep crest on the road, above a certain speed depending on the steepness of the back step of the hump, I can hear a loud bang coming from the front end when the front suspension extend after the hump apex, as if either the wheels were dropping down rather than following the profile of the road, or if the suspension had reached the end of the extension travel (topping out).

I have driven over the same humps at higher speeds with cars with conventional steel springs and they could cope without problem with the same humps. This is my first Citroen, I was wondering if someone with a better knowledge of the Hydractive 3+ suspension could tell me if this is this normal with this system or it is a sign that something is wrong?

Thanks in advance.

[vborovic]

I don't think any bang should be heard if everything is working as it should, maybe something's loose in the axle/suspension on one wheel? Possibility of closer inspection, lifting the car up with a jack, and trying to manually shake the suspect wheel to reproduce the noise?

[DickieG]

My C5 doesn't make such a noise over speed bumps, from personal experience a worn ball joint such as a drop link will knock as you describe.

[qprdude]

Mine does and it has just had a front offside strut replaced and passed the MOT with no advisories.

[myglaren]

No noise from mine other than the rear brake pad chatter - even before the ball joint replacement for the recent MOT.

[osx]

I am getting the same and will have all drop links replaced to see if it makes any difference. Ideally I would like to drive another C5 and see if it is any different.

[osx]

Mine does and it has just had a front offside strut replaced.

ouch

[rusty-pie]

I went this morning for a road test with the dealer mechanic and he too found the noise unusual, although he is not familiar with the hydractive suspension so he wasn't sure if it is normal or not on that system. Service manager is seeking authorization from the warranty department to let me take the car to a citroen dealership.

I live in Bournemouth and the local dealer is Penton in Christchurch, has anybody had any experience with them with regard to the hydractive suspension?

I am not familiar with this suspension either; I wonder if because the suspension is so much more compliant (and in my opinion less dampened) than conventional steel sprung ones, they cannot cope with speed humps at speeds that instead would be OK with other cars?

[vborovic]

If everything is working as it should, it should be the other way around, that conventional suspension can't cope with demands that are far too easy for the hydractive ...

[Northern_Mike]

I am not familiar with this suspension either; I wonder if because the suspension is so much more compliant (and in my opinion less dampened) than conventional steel sprung ones, they cannot cope with speed humps at speeds that instead would be OK with other cars?

Completely the opposite.. so much so, that I regularly used to overtake people, without breaking the speed limit, on the speed humps through village near here I used to have to drive through regularly.

Now I've got steel-sprung cars, I avoid the village altogether!

[rusty-pie]

Cheers guys, that's exactly what I thought too when I bought the car, but then the noise made me doubt about my expectations. The car is incredibly smooth over potholes even at much higher speed when only one wheel is affected, it seems that the noise is produced only when both wheels are dropped simultaneously, so I was wondering if maybe what is happening is that when both wheels are affected, when the anti roll bar is not loaded, the very low damping compared to standard suspension allows the suspension to extend so suddenly up to the point of topping out the struts?

By the way, is it normal for the hydractive suspension to have much less damping than other cars?

[rusty-pie]

Hi, the garage where I bought the car authorized a diagnostic at their expense from my local citroen dealer. I took the mechanic for a test drive and then they put the car on the ramp for a couple of hours. I spoke afterwards with their senior technician which seemed competent and knowledgeable about the hydractive 3+ system. He reported that they had inspected all the suspension components and anti-roll bar joints and could not find any fault or looseness/play. He also checked for updates of the suspension ECU software but no update was available for my car. He recons that this is a behaviour peculiar of the hydractive 3+ suspension system on C5 and C6 models. Unfortunately there was no other car in the garage at that moment with those suspension to let me try a different one on the same humps.
The mechanic deems that it could be that the wheel momentarily loses contact with the surface of the hump and the knock is caused when the wheel hits again the road. This is consistent with the feeling of dropping down a step, but I am puzzled that the wheels on a modern car can lose contact with the road at such low speeds.

Could it be possible that the suspensions are not capable of extending fast enough to follow the road profile, either by design or because of some sort of fault in the system itself?

Or maybe when they extend so rapidly one or more components in the system are temporarily unloaded and then suddenly loaded back causing the knock?

I would really like to try another C5 with Hydractive 3+ suspension over the same humps and compare. If anybody is in the Bournemouth area and fancies popping in for a cup of coffee and a quick drive down the road please let me know!

On a side note, I have to say that both the dealership where I bought the car (Westover Hyundai in Bournemouth) and the Citroen dealer (Penton in Christchurch) offered an excellent service.

[qprdude]

It would kind of depend on your speed and more importantly on the width and height of the speed bumps. I can go over the longer lower speed bumps rapidly with no thumps, but there are loads up here that are maybe 6 to 8 inches high and only 18 inches long so the incline and decline are bloody severe. My car isn't helped by having 19" low profile tyres which are very unforgiving.

[rusty-pie]

On a series of shallow humps (about 2 m long and 5 cm high) on my daily commute the critical speed is 18 miles an hour, and I can drive on the same humps at 30 miles an hour without any discomfort or fear of damaging the car. It happens only where the change of slope is quite sudden, ie flat hump with two ramps on each side rather than more rounded ones. I would not even call it a noise, but rather feels like a knock on the front end as if the car was being driven over a shallow pavement 90 degree step. I tried with the suspension in sport mode and the phenomenon is slightly reduced.

[qprdude]

Yep, mine is reduced in sport mode too. On the square bumps (where there are two side by side), I don't notice much, just on the thin, high ones really. As I said, there is no "give" with my tyres so I suspect it makes the bumps more difficult to negotiate at anything more than 10 mph.