Replaced my flat accumulator sphere, still getting a bumpy ride
  • Register
  • Help
Results 1 to 12 of 12
Like Tree1Likes
  • 1 Post By kenbw2

Thread: Replaced my flat accumulator sphere, still getting a bumpy ride

  1. #1
    Tadpole
    Join Date
    Oct 2019
    Location
    Melbourne
    Posts
    27

    Default Replaced my flat accumulator sphere, still getting a bumpy ride

    My pump was clicking once every 5 seconds, and when I took the accumulator sphere off it was definitely flat - when I put a screwdriver in to feel where the diaphragm was, I was able to put it pretty much all the way in.

    Advertisement


    I've put a replacement on - an anti sink sphere actually - and it's improved somewhat but still not doing very well.

    I've done a few tests going over speed bumps at 30kph. Most of the time it's fine, but maybe 1 in 6 times it feels very hard, like it's hitting the bump stops.

    One of the speed humps, it felt like it landed then immediately lost pressure but I could be misunderstanding.

    I've done the bounce test on all 4 corners and they all seem to bounce back nicely. And the pump is clicking way less frequently.

    Any thoughts what could be happening?

  2. #2
    1000+ Posts Ken W's Avatar
    Join Date
    Sep 2002
    Location
    North Brisbane
    Posts
    1,983

    Default

    Ken,

    Could be any number of things. When it feels hard, is that more at the front or the back or both?

    1. Changing an accumulator sphere will only affect how often and how long the HP pump clicks in the top up the system hydraulic pressure, it will not affect ride.

    2. Is your car a hydractive VSX (8 spheres) or a normal (6 sphere) Xantia? If it is hydractive, you could be bringing in the sports mode on the occasional speed bump and yes that will feel quite firm.

    3. They are never particularly good on speed bumps because the sudden change in height means most of the LHM has to go through the shock absorber flow restrictors instead of through the center bypass hole in each corner sphere.

    4. If you don't hit the speed bump exactly head on, you will feel the strong anti-roll bar action that will jostle you from side to side quite sharply.

    5. Xantias do odd things to the ride height when you are turning close to lock to lock - they usually jack themselves right up at the front. So that can cause some interesting jolts when you run out of suspension travel when they are not sitting at their centre height.

    It is best to judge how well it is riding by driving straight along a smooth but lumpy bit if road.

    Cheers, Ken

  3. #3
    Tadpole
    Join Date
    Oct 2019
    Location
    Melbourne
    Posts
    27

    Default

    Thanks for the good list of pointers. My bouncing is definitely on the rear

    1. Interesting, I guess I just attributed the rough ride to the problem I knew it had

    2. It's Hydractive. I never press the button, but maybe the ECU decides to engage sports mode?

    3. I think mine's abnormally terrible on speed bumps. I feel pain for the car the way it crashes down

    4. I was hitting these straight on, but I have experienced what you mention

    5. Interesting, I'll have to check that out

    It's generally okay on smooth road, but I definitely get the bumpiness on the motorway too if there's a particularly (relatively) severe surface height change

  4. #4
    1000+ Posts
    Join Date
    Oct 2010
    Location
    Armidale
    Posts
    2,456

    Default

    I would certainly expect a V6 to be hydractive - a VSX rather than SX model. You are right - the computer selects hard mode when it detects that you are vigorously changing direction or changing speed (in each case there is a threshold). The button changes the threshold, but doesn't lock you in hard mode. Also, it's not just an on-off switch - but should be a progressive stiffening.

    So, given that it's a VSX, you have two accumulators that do affect suspension - the hydractive spheres. You also have very well damped suspension (corner) spheres.

    So let's run a couple of scenarios. You say that at rest you can bounce each corner. When doing this the car is likely to be in soft mode - you should be able to hear a high-pitched whine. This starts up as soon as you open a door. This would imply that your hydractive accumulators are OK, but doesn't tell us much about the corner spheres - they are pretty stiff on a VSX, and in soft mode it is the hydractive accumulators that you are testing. It may be that some or all the suspension spheres might be partly or totally flat - but the computer has no way of knowing this, so as soon as it switches even partly to hard mode, your ride can get very harsh.

    Alternatively, your hydractive system might not be working - if you can't hear the high pitched whine (most audible if the car is in a garage) then in all probability it is not - or the system might be working but the hydractive accumulators might be flat. Then if your corner spheres are good, you would be able to rock the car at rest (although it would seem very firm), but the ride would be very harsh.

    My advice is to start with new spheres all round - you are going to need them sooner or later, and it makes trouble shooting so much easier. Unfortunately Sphere-shop (online store) has closed, but they are still being manufactured by IFHS and others. It is not too difficult to find suppliers, and often the freight is the same for a large or small order. I did that for both a Xantia SX, and my XM VSX - transformed both of them.

    Cheers

    Alec

  5. #5
    Tadpole
    Join Date
    Oct 2019
    Location
    Melbourne
    Posts
    27

    Default

    Quote Originally Posted by Armidillo View Post
    I would certainly expect a V6 to be hydractive - a VSX rather than SX model. You are right - the computer selects hard mode when it detects that you are vigorously changing direction or changing speed (in each case there is a threshold). The button changes the threshold, but doesn't lock you in hard mode. Also, it's not just an on-off switch - but should be a progressive stiffening.

    So, given that it's a VSX, you have two accumulators that do affect suspension - the hydractive spheres. You also have very well damped suspension (corner) spheres.
    It definitely has Hydractive, I can't speak for whether it's VSX or SX. It's also a 2.0 16v i4 rather than the v6 version

    Quote Originally Posted by Armidillo View Post
    So let's run a couple of scenarios. You say that at rest you can bounce each corner.
    I did just try this again. To quote what I said on Frenchcarforum.co.uk:

    Car's been off all night and doors closed. There's definitely much more give in the front suspension than the rear. The rear does what you describe where the tyre sidewall has more give than the suspension. So I guess that's it.

    Quote Originally Posted by Armidillo View Post
    When doing this the car is likely to be in soft mode - you should be able to hear a high-pitched whine.
    I did hear the whine after opening a door, yes

    Quote Originally Posted by Armidillo View Post
    Then if your corner spheres are good, you would be able to rock the car at rest (although it would seem very firm), but the ride would be very harsh.
    It does rock, but actually most of this seems to be tyre sidewall rather than suspension

    Quote Originally Posted by Armidillo View Post
    My advice is to start with new spheres all round
    It does sound like this is what I need.

    Thanks for the suggestions, this helps a lot

  6. #6
    1000+ Posts
    Join Date
    Oct 2010
    Location
    Armidale
    Posts
    2,456

    Default

    Rear should be much softer than front - certainly sounds like flat rear spheres at least.

    They can be regassed, but only if diaphragm is intact. In any case, unless you were able to give them an annual check/top up, you are unlikely to be able to regas more than once. I bought an XM earlier this year - spheres were mostly about 8 years old, and had been regassed in 2015. Ride was just about perfect when I collected it.

    By the time I'd driven it 500 km home, they were starting to go pop - the ride was no longer as good. One went bang while I had my head in the engine bay - it was not flat (which will destroy diaphragms), because the rush of N2 blew the lid off the LHM reservoir, and made the LHM appear to be boiling for some time!

    So I've concluded that, for single membrane spheres, only consider a regass if they are not more than 4yrs old, and not fully flat. Finding someone with a regassing rig is also a problem!

    Cheers
    Alec
    Last edited by Armidillo; 9th November 2019 at 01:11 PM.

  7. #7
    Tadpole
    Join Date
    Oct 2019
    Location
    Melbourne
    Posts
    27

    Default

    As it happens I'm off to a guy now who regases spheres to attempt one on my accumulator.
    Armidillo likes this.

  8. #8
    1000+ Posts Ken W's Avatar
    Join Date
    Sep 2002
    Location
    North Brisbane
    Posts
    1,983

    Default

    Get him to check your rear corner and centre soft sphere pressures. It may just be a lazy rear hydractive valve - they will only switch to soft when the car is operating at full hydraulic pressure. Tell me if you want to know more.

    Cheers, Ken

  9. #9
    Tadpole
    Join Date
    Oct 2019
    Location
    Melbourne
    Posts
    27

    Default

    I've just come back (regassed accumuator in hand) and he did the bounce check on all four corners. He's decreed the bounceback to be "a little firm but seems fine" on all four corners.

    Driving round today after having done some Citrobics has definitely improved things a lot. It did get bumpy again after I braked hard. The aforementioned club owner suggested this could be that braking hard used up a lot of the pressure, which was depleted more quickly because I have the anti sink sphere on the front.

  10. #10
    1000+ Posts Ken W's Avatar
    Join Date
    Sep 2002
    Location
    North Brisbane
    Posts
    1,983

    Default

    The hydractive system has a pressure switch in the braking circuit. If your braking pressure gets about a certain pressure and you are travelling over 40 km/hr, the suspension will switch into firm mode for a few seconds or until you stop braking. The other time it jolts you around is when you drive over a hump in the road that would normally let the front suspension float a bit high, the hydractive system senses the rise in suspension height, goes firm and drags the nose down quite savagely. I have noticed the same behaviour crossing a certain intersection in both my Activa and the C5X7.

    Here is some more reading for you.

    My new Xantia CT

    Cheers, Ken
    Last edited by Ken W; 9th November 2019 at 10:28 PM. Reason: add link

  11. #11
    1000+ Posts Ken W's Avatar
    Join Date
    Sep 2002
    Location
    North Brisbane
    Posts
    1,983

    Default

    Ken and Co,

    Here are some links to helpful documents from my Dropbox. The CitroenGuide has a good description of Hydractive and Activa systems. The Other document on Hydractive gets a bit more technical.

    https://www.dropbox.com/s/95kbi8nwp5...e%202.pdf?dl=0

    https://www.dropbox.com/s/a160bx0qw9...on_UK.pdf?dl=0

    I have more if you want them - send me a PM.

    Cheers, Ken

  12. #12
    Fellow Frogger!
    Join Date
    Dec 2010
    Location
    canberra
    Posts
    172

    Default

    Should the diodes be checked/replaced, they have a history of failing & putting the car in sports mode?

    Regards

    agd123

Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •