C5 Suspension

[onthecut]

Hi Guys.

OK, I know it's the wrong forum -- but definitely the best and someone will know !

Neighbour has a C5 and is suffering a marked clonk from the rear suspension. It's as though the pistons aren't keeping pace with the susp. arm travel, resulting in a clonk as the rod contacts the piston again after, say, going over a speed bump or similar. Have had a look underneath and there is nothing visibly broken. (Interesting from the XM perspective that whereas our cars have a steel subframe and ally arms, this is the other way round.) In ordinary use, the ride is fine.

Any thoughts or known issues most appreciated.

Mike.

[Peter.N.]

Hi Mike

Don't know if this is applicable but I had a similar noise on my XM, when I took it in for MOT last week our friendly local mechanic pointed out that one of the anti roll bar bolts was missing. When I put it on the ramp i found that actually both bolts were missing on the n/s and loose on the o/s . Only suggesting that a loose bolt may be the problem - do C5's use bolts?

Peter

[Dieselman]

Alternatively one of the spheres may be flat or ruptured which causes lack of spring so the piston doesn't react as quickly as normal.
In addition check the subframe bolts are tight.

[onthecut]

Hi Peter.

Thanks for the suggestion. It's a bit of a different set up to the XM --- the roll bar is a seriously heavy bit of kit, secured to each arm by one hefty bolt. Didn't see the anchorage to the beam, but nothing obviously loose.Most noticeable though is that the height sensor appears to be an electrical sender, so presumably the valve is electronically controlled as well. I wonder if some bit of the electrics isn't getting the right signal to the valve fast enough, or correctly, if that is indeed how it works.

Mike.

[Geoff Lebowski]

I have the same on my 51 C5! If memory serves, it was a common problem on early C5s. I've yet to investigate further, mine is annoying but otherwise seemingly harmless.

[Dieselman]

Check the subframe mounting bolts are actually tight and look for worn suspension bushes.

[citroenmad]

The radius arm bearings will cause a clunk if they are worn. Its often the only way to tell if they are in need of replacing, as the C5 doesn't seem to suffer the usual camber problems when the bearings wear. Its not uncommon on C5s for this clunk to happen due to the arm bearings.