Xantia Suspension/Brakes - rise and fall

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andrewphillips
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Xantia Suspension/Brakes - rise and fall

Post by andrewphillips » 31 Jul 2002, 16:18

Xantia Vsx
Can someone confirm diagnosis and advise on correct way of doing this please
Rear drops on reversing and braking
Front drops on switch off
There is always air at bleed screw on front pressure regulator
Where does it all come from ..
It rides fine but getting slower to rise and drops more - this seems to be alleviated temporarily by releasing air from press reg
Cleaned crud off rear height corrector and all seems present and correct
Have changed front discs and pads within last 1000 miles but can't see connection
Miles 60k 1994
Although full Citroen history can't see evidence of fluid change although has had rear spheres
Assume it needs bleeding - both brakes and suspension
Have read the articles on this but would like confirmation on following:
1/. Should I change all fluid / is it worth using hydraflush ?
2/. What quantities of LHM do I need
3/. What order to bleed in and do I need the wheels off ?
4/. Have I missed the point completely and these are symptoms of something else
5/. Are VSX's any diff from normal when it comes to bleeding? i.e. do I need to worry about the ride switch setting or do I bleed in each setting ?
Thanks
Andrew
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Dave Burns
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Post by Dave Burns » 01 Aug 2002, 02:15

Hi, what makes you think there is air getting in to the accumulator.
Does the car have anti-sink fitted.
Can't make any worthwhile connection between reversing and sinking, explain how this occurs, sinking and braking can be related, depend's how and when, i.e when you brake to a halt the car can sink slightly at the rear when you release the
brake's.
Longer rise time's can mean internal leakage of hydraulic component's, or restricted filter's.
Dave
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andrewphillips
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Post by andrewphillips » 01 Aug 2002, 23:24

Dave,
some more details as requested to refine your diagnosis
Car is a VSX 2.0 Auto -
Hi, what makes you think there is air getting in to the accumulator.
About 10 days ago on start up car did a nodding donkey impersonation on start up in Morning.
Front rose and fell - ride height etc all set to normal.
Previously no problems or any such behavior.
So after initial panic decided to be logical.
Set suspension to low open bleed valve on regulator - lots of air.
Restarted - much improved but still doing "nodding", repeated bleeding - engine running- on normal and high.
Everything now fine STOP light went out really quick on start up , 2 secs had been 20 secs
Checked level LHM (ok)
Situation deteriorated over next 7 days in that STOP taking longer to extinguish and rear would drop on braking.
(Don't seem to recollect this before though have read elsewhere this a normal part of anti-dive behavior)
So checked for air at bleed valve on regulator and lots.
Once let this out STOP lamp extinguishes in 2 Secs again and not the pronounced drop on braking there was previously.
I can always bleed off some air here even if I only bled it minutes ago - now this may be normal but methinks not -
So the ever present air here and the behavior of rear and increasing time to extinguish STOP leads me to believe airs getting in.
Does the car have anti-sink fitted.
Car does have anti sink fitted
Can't make any worthwhile connection between reversing and sinking, explain how this occurs, sinking and braking can be related, depend's how and when, i.e when you brake to a halt the car can sink slightly at the rear when you release the
brake's.
May be no connection Car does rise at rear when braking in reverse as I back out of driveway (but I live on a slope) and rear drop on braking on level.
So trawling through internet/haynes.bulletin board decided that this could be caused by air in suspension or more likely rear brake circuit necessitating complete system bleed.
Thought I'd seek confirmation and advice before I attempt to fix.
Car rides fine (Really I should say brilliantly - this may be heresy but better than previous BX's - VSX's seem better than other Xatiae not so hard and uncompliant )
Brakes good - need to press slightly harder when you have nearly stopped as braking force seems to get momentarily less.
ABS works
Only thing I,ve done so far is clean off crud around rear ride height corrector and check all linkages lubricated and present . (All was o.k.)
Andrew
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reffro
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Post by reffro » 02 Aug 2002, 00:53

You've just about described how my VSX runs too. But it doesn't do the up and down dancing at start up. The stop light will extinguish after 5 secs usually. It does like to pop the front up after hard braking, or if manuovering in tight spaces involving lots of turning of the steering wheel. It will put its rear up when reversing also, or if you are accelerating hard round a bend, but it soon sinks back to normal. Sometimes mine needs a little extra push on the brake peddle when pulling to a stop, nothing serious though. Oh and its very comfortable too, and the sports suspension setting works a treat on fast twisty roads. I've just had all the spheres replaced by the way, which replaced the shocking ride and variable braking previous to their replacement.
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Dave Burns
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Joined: 14 May 2001, 05:30
Location: United Kingdom
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Post by Dave Burns » 02 Aug 2002, 04:05

First off I think you are mistaking the sound high pressure oil or any fluid makes as it is force through a small orifice.
There will be a hissing or whistling sound when the release screw is turned, this is normal.
If there were this amount of air getting in you would be experiencing very much worse behaviour from your car.
The nodding donkey bit I think is stiff operation of the height corrector(s) or more to the point, their linkage's.
when they move smoothly as pressure build's and begins to lift the car, the anti roll bar rotate's and exert's force on the linkages, the valve in the h/c begins to close as the correct height is neared, and closes as it is reached.
With poor linkages the anti roll bar will rotate and exert force on the linkeges and spring's, but because they are not moving will travel past the point where the valve should have closed, eventually enough force is applied and the linkage moves, but it has already gone past the closed valve point and immediately opens it to the return with the result that the suspension then drops, the same thing can happen on the downstroke, at some point it loosen's a bit and settles though may be at the wrong height.
Before you go any further you need to be absolutely sure the height corrector's are being worked as they should.
Forget about air for now, the suspension cycles you have gone through should have purged any from the suspension, any trapped will be between the brake valve and the rear calipers.
If you are going under it make sure it is properly supported and preferably on a pair of ramp's, yanking on the linkage underneath can bring it down very quickly.
Dave
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