C5 Suspension Knocking

blueboy2001 · Unread post by **blueboy2001** » 19 Feb 2004, 22:58

I've just been to see an 03 plate C5 2.2HDi SX with 21k on the clock. It seems fine, I've done the deal but the o/s rear suspension is knocking like a goodun on rougher surfaces.
I was led to believe that this problem was sorted from 2002, my last C5 of nigh on the same age was absolutely fine.
Is there a proper fix available from Citroen for this problem? Car is still under warranty, but I'm loathed to shell out for the car if its going to constantly recur, and if anyone is going to wear out suspension components on a car it's me as I drive down all manner of potholed tracks every day.
I've got until midday tomorrow to give word on the car.

bencowell · Unread post by **bencowell** » 19 Feb 2004, 23:31

Blueboy, glad you are ready to come back to the nest, I was going to hastle my dealer about knocking noises again. Had the rear axle replaced and it may be worse than before with the extra 2kg weights.
Take a look in the boot and under the rear seats to see if soundproofing has been added. It is a different colour to the original and cut into many pieces.
Check the ORGA number of the new C5, it may have been in a field waiting for a while. Alternatively, the car may have had a repair done at the factory and taken a while to roll off the line and may have older suspension components as a result.
Still loving my C5 despite its knocks.

blueboy2001 · Unread post by **blueboy2001** » 20 Feb 2004, 00:53

I'll talk to the Service manager at the dealer who used to do all my servicing and get his opinion, but if something can be done I'll buy it, I've agreed a good price.

paranoid · Unread post by **paranoid** » 20 Feb 2004, 12:30

Workmate was talking to cit mechanic at dealer yesterday, Citroen are working flat out to sort problems on c5's especially suspension,speres links etc They do not want the same reputation that the xantia has, apparantly many thousands have been spent due to spheres wearing out in double quick time, They want C5 to be big seller, his advice was keep badgering the dealer if your not happy because they won't fix the cars unless people ask !!!![:D]

Doc · Unread post by **Doc** » 20 Feb 2004, 21:07

Blueboy, go onto www.honestjohn.co.uk and click on Car by Car breakdown. Select Citroen then C5 and you may want to read what it says. Apparently the knocking has been solved by dealers changing "the rear shock absorbers" By this I think they mean spheres and/or rear struts! Anyone who may be looking to buy a C5 will find this site useful. The C5 is also going to have a major facelift in September '04 which should have a knock on effect for used C5 prices
Hope this helps.

wheeler · Unread post by **wheeler** » 20 Feb 2004, 22:34

i think the main problem with the rattles/knocks is that very slight noises are amplified by the huge hollow cross tube on the rear axle which acts like a big bass drum,hence the soundproofing.

Doc · Unread post by **Doc** » 21 Feb 2004, 21:05

A good point about the hollow X-tube amplifying sounds. As I mentioned earlier, Citroen dealers have been changing rear strut/sphere assemblies to cure knocking as adding extra weights doesn't work. Anyone out there know the EXACT reason for this knocking?

alexx · Unread post by **alexx** » 21 Feb 2004, 21:36

I tried to find out several months ago, but didn't find any useful info about that on the net. Of course, replacing hydractive spheres with non-hydractive ones, adding some weight to suspension elements and sound isolation material doesn't seem to be a correct solution.

Doc · Unread post by **Doc** » 22 Feb 2004, 12:17

Hello Alex, by the lack of information on the net about the C5 knocking, I suspect Citroen have been keeping very tight lipped about the problem. My own theories about this knocking revolve around a possible incorrect machining/manufacturing tolerance on the rear trailing arm/strut assembly, therefore causing excess movement.
Are there any Citroen technicians out there that wish to set us right? The C5 is gaining in popularity and many people on this forum have already bought or about to buy a C5.

AndersDK · Unread post by **AndersDK** » 22 Feb 2004, 17:31

From the BX & CX lots of owners knows about the usual problems causing knocking from the rear suspension - by common wear symptoms.
Despite the huge count of Xantiae on the roads - these do not seem to suffer such problems to the same extent.
Uncontrolled production machining tolerances on C5 could very well cause same symptoms as wear.
Out of pure technical curiousity I find this problem very interesting.
And with a heart belonging to Citroen hydropneumatic cars it hurts to see reports (again !) of a new model struggling into life.
From the BX I'm aware of these known problems causing a knocking sound impression from driver's seat :
1) Exhaust pipe where it bends under the rear X-tube.
2) Transverse damper box knocking transversely against the rear subframe in it's mounting hooks.
3) Rear damper mounting hook breaking off due to rust (from boot box) - making rear damper rattling around.
4) Defective rear arm pivot bearings (slack).
5) The antiroll bar grindng in it's mounts underside of rear arms.
6) Rear doors rattling on the lock poster (nylon bush worn by the catch)
7) Wheel caps loose grip on wheel bolts
8) Spare wheel cage rattling in rear hook or front pivots.
9) Jack & winder handle rattling in the boot.
From the CX I know of these symptoms causing knocking from rear :
1) Too soft (worn) rubber hangers for rear exhaust box
2) Rear arm pivot bearings
3) Anti-rollbar clamp inner side of rear arm dry.
4) Rear doors rattling on door lock poster (no nylon bush on the CX)
5) Rear wheel arch plastic covers loose fit.
I've never experienced problems with the rear suspension cylinder & sphere mounting details - UNLESS severe faults occurred - like a snapped piston rod (common on BX).
I suspect that the piston rod in it's pivoting balljoint in the arm could cause knocking if loose fit or tolerances here - but it's hard to believe that accelerations from suspension bouncing are faster than the acceleration capabilities from the sphere/cylinder.
Could this be the C5 problem ?
The C5 rear arm rubber damper block we know of.
Other symptoms you know of out there ?

DLM · Unread post by **DLM** » 23 Feb 2004, 18:43

Hmmm.... I've been following this one from afar - because my BX is still giving me good service and I have a maybe irrational dislike of the Xantia (heavy as sin, and as such completely counter to the design philosophy of the BX, looks more like an Audi than a Citroen....etc.). However, the C5 estate (in diesel form. of course) strikes me as a Citroen worthy of the name, and some years from now I hope to be able to afford one secondhand - assuming that there's anybody independent left to help repair them after the end of the guarantee period for the suspension.
This sounds to me like a sphere or resonance problem. Newbie Citroen drivers buying hydropneumatic Citroens do seem to be of the opinion that Citroen spheres don't wear out, and I wonder if just a small decrease in the life of spheres with the new system could be causing some of the complaints. If it's an active system then that very "activity" could be harmful to sphere membranes in the medium to long term. Are the rear axles units different in diameter or material compared to previous Citroens?
On the other hand I haven't heard the banging myself, so perhaps should't guess.
Certainly a viable point of view if Citroen are changing the spheres themselves.... and it's worth noting that on older hydrocits the cause of choppy ride or rattles is very difficult to pin down exactly, as Anders points out. I've just had very worrying rattles from a loose spare wheel holder on my BX, and also inconsistent front ride problems totally cured after swapping over to newer front spheres (taken from my spares BX).
At least the C5 interiors shouldn't rattle like a BX!

tomsheppard · Unread post by **tomsheppard** » 23 Feb 2004, 18:56

The most worrying noise my BX made was caused by my putting the sphere I'd just replaced in the well between the washer bottle and the heater and forgetting I'd put it there.
Terror turned to sheepish embarrasment as soon as I opened the bonnet!

Doc · Unread post by **Doc** » 23 Feb 2004, 20:26

If Citroen can't or won't say what the problem is then maybe it will take a C5 owner with a 'problem car' to attach a small video camera and microphone underneath the back end and hopefully record unusual noises and observe any component movement in relation to road conditions and vehicle speed. It may make an interesting project for any C5 owners, automotive engineers/engineering students.
Let's hope the problem is solved before the C5 slips out of warranty as I wouldn't like to guess the parts and labour cost to replace the rear strut assemblies.

Doc · Unread post by **Doc** » 23 Feb 2004, 20:35

I think it was Wheeler who suggested that the large suspension X-tube could be amplifying any 'normal' sounds. Perhaps the rear tube could be filled with a polyurethane-type expanding foam to deaden any sound waves. I understand Jaguar did a similar thing with XJ series front cross members/subframes, though not sure if this was an attempt to cure NVH. Anyone know for sure?

bencowell · Unread post by **bencowell** » 24 Feb 2004, 02:08

The rear axle was filled with foam at one time, although they discontinued that idea now.
Spheres are changed and supposed to last forever, fluid changes scheduled at 5 years or 100k.