Xantia Hdi Exclusive Suspension still to hard

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co04pow
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Xantia Hdi Exclusive Suspension still to hard

Post by co04pow »

Hi,

I have 1999 V reg Xantia Hdi Exclusive. When I bought the car the suspension was very hard compared to my previous Hdi SX so I thought I would change the suspension shperes so I did the lot. The 4 struts, 2 centres, accumulator and anti sink and changed the LHM and blead the system. What a difference to the brakes by the way! Anyway it still felt hard. After some research on this forum I did the Diode fix in the hope it would sofen it up. I think it has but still nowhere the super smooth ride of the previous Hdi SX. After more reading I have started to investigate the electrovalves. I have done the checks, run the car, feel the suspension the rear soft and the front not so, stop the engine, I can here the valves hum then after 30 sec a good clunk, Should there be a hum from both front and back and a clunk from both? Then the suspension is much harder front and back! a definite difference. Then open the door and another clunk and softer again but the back more than the front. So my question is why is the front still hard while driving it seems to be going from Soft to hard mode ok but the soft just doesn't feel soft enough for me. Certainly the front more so than the rear. The spheres I fitted where all from http://www.aep.com" onclick="window.open(this.href);return false; in Glasgow. Anything I can do to investigate the electvalves further? Try new spheres on the front? The middle one anyway? Hydraflush? Any help would be much apreciated.

Thanks
2000 W reg Xantia V6 Exclusive (Green)
1999 V reg Xantia 2.0 HDi Exclusive (Dark Grey)
2000 X reg Xantia 2.0 HDi SX (Dark Grey)
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Re: Xantia Hdi Exclusive Suspension still to hard

Post by CitroJim »

Unless I'm beaten to it, I'll go into some fine detail tomorrow on the possibilities..

Can't now, just about to fall off my perch :twisted:
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Re: Xantia Hdi Exclusive Suspension still to hard

Post by Lighty »

Personally I would test the spheres, quite possible to get duff ones.
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Re: Xantia Hdi Exclusive Suspension still to hard

Post by Mandrake »

AEP spheres should be fine - I fitted a full set of AEP spheres (IFHS brand) to my V6 Exclusive a few months ago and no complaints there. (except for a spot weld bump on the mating face that I had to file off on one!) I guess its always possible you have a DOA sphere, the most likely candidate would be the front hydractive regulator sphere as this will make the most difference to ride quality at the front.

I notice you also have a V6 Exclusive, how does the ride compare to that ? What do you notice if you have both cars side by side and do a bounce test on both cars in both soft and hard mode ?

You'll probably find the front of the V6 a bit stiffer than the HDi when doing a bounce test because the V6 is a heavier car at the front thus the front suspension is a bit stiffer. However you should notice a proportional change between hard and soft on both cars.

Sounds like you've checked the obvious things, how about the ride height ? As little as 20mm too high or too low can have quite an impact on the ride quality. If the height corrector linkage is sticky the ride height may be inconsistent even if its correctly adjusted leading to intermittently poor ride.

Have you tried lubricating the front strut shafts with LHM ? Search the forum on how to do this, basically lift the suspension right up, put axle stands under both jacking points under the front doors so that it can't drop down on your hands, drop the gaiter on the strut down and you'll see a shiny shaft. Give it a good smear of LHM especially near the bottom of the shaft then refit the gaiters, (try not to get any on the lip where the gaiter attaches or it may slip off later...) remove the axle stands and fully lower the suspension then raise to normal height.

If you've only recently fitted the spheres I presume you did a full set of Citreorobics afterwards ? EG lift the suspension up full for 2-3 minutes then right down for 2-3 minutes, repeat a couple of times, to flush out any air that would have entered when fitting the spheres ?

Hows your regulator cycle time ? If the accumulator sphere is new or recently replaced yet the cycle time is short (less than 30 seconds) it could indicate an electrovalve with internal leakage - usually the front electrovalve. If the leakage is bad enough it can interfere with the soft/hard mode switching causing the front to be hydraulically in hard mode even though the ECU is energising the electrovalve.

Let the car idle then turn off the engine, close all doors, listen down near the bumper near the electrovalve - if you hear a hiss that stops after the electrovalve click 30 seconds later you definitely have a leaky electrovalve. (It takes quite a big leak to be audible)

When you say the ride is hard do you mean that it is harsh on broken surfaces or just hard in general even on smooth surfaces ? If its very harsh on broken surfaces you could have drop-links that need doing, possibly lower ball-joints.

Theres a few things for you to try. :) Where abouts in Scotland are you ?
Simon

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Re: Xantia Hdi Exclusive Suspension still to hard

Post by CitroJim »

Thanks Simon, that's covered almost all of it really. I only have a few points to add :-D

So, the fact you can hear hums and clunks and feel a difference both front and rear shows the electrovalves are doing their thing.

The front centre sphere is a big 'un and pumped up very high. 72 bars I believe. If it's the wrong one or low then the front will feel harder than it should, Also, given the very high pressure in the front centre it needs a good pressure differential to allow the isolating shuttle in the hydractive valve block to open fully and allow the sphere to do it's work. That there is a difference in softness on a static test does not necessarily mean the suspension is switching reliably dynamically and this can be down to low main system pressure.

If all of Simon's checks draw a blank then it will be wise to check the pressure regulator is working as it should and is correctly cutting in a 145bar and cutting out at 180bar. Over time the cut-out pressure falls as the regulator springs get a little tired. I've found the cut-out pressure to be quite critical on a hydractive car and it doesn't take a lot of reduction before funny suspension faults begin to occur.

Testing it a bit tricky but if you're handy with a lathe and brazing it's not hard to make up a test gauge like this:

Image

And in use:

Image

Do check again the centre hydractive sphere as a ruptured or flat one in this position can throw up some real oddities. You can still feel a difference in stiffness but it's not right. As said, even new spheres can be duff occasionally.
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Re: Xantia Hdi Exclusive Suspension still to hard

Post by Mandrake »

CitroJim wrote:Also, given the very high pressure in the front centre it needs a good pressure differential to allow the isolating shuttle in the hydractive valve block to open fully and allow the sphere to do it's work. That there is a difference in softness on a static test does not necessarily mean the suspension is switching reliably dynamically and this can be down to low main system pressure.

If all of Simon's checks draw a blank then it will be wise to check the pressure regulator is working as it should and is correctly cutting in a 145bar and cutting out at 180bar. Over time the cut-out pressure falls as the regulator springs get a little tired. I've found the cut-out pressure to be quite critical on a hydractive car and it doesn't take a lot of reduction before funny suspension faults begin to occur.
Glad to hear you say that Jim, I've long been suspicious of marginal pressure differential being a source of harsh ride on HA2 Xantias. From memory the front suspension pressure of my previous Xantia measured around 110-120 bars unladden, increasing further when loaded with passengers etc. Not a lot of differential even at the correct 145 bars let alone if the regulator pressure is sagging with age.

Another important point is even if the pressure regulator pressure is higher than the static suspension pressure that doesn't allow for dynamic spikes in suspension pressure caused by hitting bumps. It's my belief that sometimes the the dynamic pressure in the suspension exceeds the pressure regulator pressure causing the shuttle valve to slide to hard and back during the transition of a bump causing a harsh jolt.

I have an idea for a simple fix for this problem but I don't want to hijack this thread... I did describe it down near the bottom of Spaces ride deterioration thread, so perhaps there or a new thread would be a good place to discuss it:

http://www.frenchcarforum.co.uk/forum/v ... =3&t=41030" onclick="window.open(this.href);return false;

Basically it should be possible to add a simple one way ball valve in the high pressure inlet feed to the electrovalve. (One of the two small pipes going into the hydractive regulator block)

That way even if the dynamic pressure in the suspension exceeds the inlet pressure no back flow is possible so the shuttle will remain locked in soft. This should be a more thorough cure than boosting the cut-in pressure which I've read some people doing.

Can you think of a female to female union with a one way valve in it anywhere in the Xantia which could be taken from a wreck and repurposed ? With a union like this and a short loop of pipe it should be very easy to retrofit this to any HA2 Xantia in minutes, by inserting it in series with the pipe entering the hydractive regulator block.

What do you think Jim ? If you want to take this to another thread to discuss further that's fine, I'm quite keen to see this idea tested as it's something I came up with years ago but never got a chance to try due to not being able to find a suitable one way valve. I really do think it could make quite a difference to ride quality especially on those HA2 Xantias that suffer from the dreaded inexplicable intermittent harsh ride.
Simon

1997 Xantia S1 3.0 V6 Auto Exclusive in Silex Grey
2016 Nissan Leaf Tekna 30kWh in White

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Re: Xantia Hdi Exclusive Suspension still to hard

Post by rory_perrett »

On my Hdi Exclusive the hard suspension was due to the car being in firm mode all the time. Found it when I got a lexia. The suspension ecu had failed and was not switiching the front valve to soft. When you switched the car on the rear would go to soft and then immediately switch to firm. Changed the ecu and all was fine again.
Last edited by rory_perrett on 06 Sep 2012, 16:22, edited 2 times in total.
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Re: Xantia Hdi Exclusive Suspension still to hard

Post by Peter.N. »

For a quick fix fit non hydractive spheres and unplug the suspension ECU.

Peter
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Re: Xantia Hdi Exclusive Suspension still to hard

Post by CitroJim »

Peter.N. wrote:For a quick fix fit non hydractive spheres and unplug the suspension ECU.
It works :-D Not quite as good as a proper non-hydractive but I did this for a while when I was chasing my fast tick in soft problem on my old V6...
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Re: Xantia Hdi Exclusive Suspension still to hard

Post by CitroJim »

Mandrake wrote: What do you think Jim ? If you want to take this to another thread to discuss further that's fine, I'm quite keen to see this idea tested as it's something I came up with years ago but never got a chance to try due to not being able to find a suitable one way valve.
It's a very interesting thought Simon and definitely worth a shot I think, I can't think of anything on a scrapper that might suit the purpose but then again, a bit of lathe work, a ball and a spring would soon see one made that should do the job admirably... Then just a short length of pipe flared at both ends and it would be in. At least access is very easy...
Jim

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