2.0. Hdi C5 wierd suspension fault

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2.0. Hdi C5 wierd suspension fault

Post by Peter.N. » 03 Apr 2013, 17:13

All the spheres were pretty flat when I bought this car, I changed the front ones and immediately had about 4" of movement. After not using the car for a couple of months the rear had gone solid, thinking it was the spheres I bought a new pair, fitted them, no different, you can't push the back down at all although you can sometimes lift it up an inch or two.

I then concluded it must be the radius arm bearings so I bought some of those too, when I jacked the car up the arms were moving fluidly. I then got onto the firm I bought the spheres from who said they had never had two fail, I said 'neither have I', send them back and we will test them.

Today I fitted two XM accumulator spheres which should make it move like a DS but its more or less the same except that if you keep trying to bounce it, it will loosen up until the pump cuts in and lifts it then it goes solid again. It does this at any height setting so its nowhere near the bump stops.

Could it still be the radius arm bearings seizing when under load, they move freely enough when jacked up - help. 8-[

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Post by addo » 04 Apr 2013, 08:26

I'd be having a proper look at the rear cylinder pushrods/seats. Although if its not making cracking noises failure here is unlikely.

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Post by addo » 04 Apr 2013, 09:09

Could it otherwise be a blocked exhaust?

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Re: 2.0. Hdi C5 wierd suspension fault

Post by Peter.N. » 04 Apr 2013, 09:56

Thanks for the comments. It has not been making any noises at all and its the same both sides, when I can get it to move it feels normal and then goes solid again. In 30 years of running hydropnumatics I have never come across anything like it.

Peter

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Post by addo » 04 Apr 2013, 10:11

Just for laughs, uncouple the rear anti-roll bar at one side and see if it makes any difference.

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Re: 2.0. Hdi C5 wierd suspension fault

Post by Peter.N. » 04 Apr 2013, 11:31

That's a thought.

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Re: 2.0. Hdi C5 wierd suspension fault

Post by Mandrake » 04 Apr 2013, 16:16

It could still be the rear suspension arm bearings Peter - just because the arm moves smoothly while its hanging loose with no load on it doesn't really mean anything, as soon as the weight of the car is supported by the arm there is a large amount of side thrust on each bearing due to the horizontal offset of the wheel from the half way point of the bearings...if the bearings are totally shot they'll bind up when that side thrust load is there but will probably be loose and turn easily when the arm hangs loose, maybe even a little too easily if there is a lot of clearance in the destroyed bearing(s).

Addo's idea to disconnect the roll bar is a good one - it could be only one side that has shot bearings but because the roll bar is so stiff it will prevent both sides moving. If you bounce on one rear corner then the other while the roll bar is still connected you might notice one side is slightly more springy, but disconnecting it would tell you for sure...

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Re:

Post by Mandrake » 04 Apr 2013, 16:22

addo wrote:Could it otherwise be a blocked exhaust?
Now you're just baiting me :-D :twisted:

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Re: 2.0. Hdi C5 wierd suspension fault

Post by Peter.N. » 04 Apr 2013, 16:57

Thanks Simon, I will try disconnecting the anti roll bar before anything else but I cant see that it can be anything else really although I have had no squeaking from the bearings and there doesn't appear to be any movement in them - except up and down.

Peter

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Re: 2.0. Hdi C5 wierd suspension fault

Post by Mandrake » 04 Apr 2013, 17:32

It's a Hydractive 3 not 3+, correct ? So only 4 suspension spheres instead of 6 and no sport/normal mode ?

If so, and given that its correcting the ride height to somewhere in between the bump stops (not pressing against them) it really can only be something mechanical not hydraulic...When you don't have the hard/soft switching of Hydractive 3+ I can't think of anything hydraulic that could cause it.

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Re: 2.0. Hdi C5 wierd suspension fault

Post by Peter.N. » 04 Apr 2013, 21:17

Exactly. My 2.2 had the three spheres and worked beautifully but this one has gone back to CX days so I thought it would be reliable :( The strange thing is that if you can get it moving its quite fluid until either you stop or the pump cuts in, it will probably turn out to be the bearings but the symptoms are just not right.

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Re: 2.0. Hdi C5 wierd suspension fault

Post by Xantidote » 04 Apr 2013, 21:51

Does the C5 have a height corrector like the Xantia, or is it an electrical gizmo/control? Just thinking that if it's electrical, then maybe there's a linkage to a contact moving on a potentiometer, and maybe the sliding contact/potentiometer is worn, and only giving an intermittent signal to the cpu - just an idea, or thereagain, maybe I'm up the garden path

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Re: 2.0. Hdi C5 wierd suspension fault

Post by Hell Razor5543 » 04 Apr 2013, 22:03

It is not a potentiometer. There is a box with a circuit board in it, with a high number of contacts. I cannot say who posted it, but there was a post with photographs for, IIRC, the rear height corrector and how to fix it.

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Re: 2.0. Hdi C5 wierd suspension fault

Post by Peter.N. » 04 Apr 2013, 23:06

Yes, its an electronic gizmo but its working OK as the height adjusts all right and if you sit on the back it pumps up and then drops when you get off.

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Re: 2.0. Hdi C5 wierd suspension fault

Post by Xantidote » 04 Apr 2013, 23:30

Ah right, I think I was a little off track there Peter - a senior moment #-o