Sphere shenanigans
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  1. #1
    Tadpole
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    Default Sphere shenanigans

    Morning all,

    I was hoping to check my facts before I put on my best frowny face...

    I pulled all my spheres off my BX 16V for regassing last weekend and took them off to a Citroen specialist workshop. When I got them back, they had pressure tested the spheres and found one rear sphere was beyond hope (no surprise there) and replaced it. I use ordinary BX 19 spheres rather than the 16V as they're comfier
    However:
    • The front spheres were tested and were marked for use on the rear
    • The dead sphere (which was a rear sphere) was replaced with a 16V front sphere
    • The other rear sphere was regassed and marked for use on the front.


    Which looks well dodgy to me, so I did some homework at http://citroen.tramontana.co.hu/susp...cement-spheres
    where it shows that the bore diameter is different for front and rear and 16V and standard BX19.

    So I have two markedly different spheres (one rear, one front) on the front and to front spheres on the rear.

    Am I right in thinking that this isn't good enough? I intend to give the workshop the opportunity to put this right, but I need to be sure of my facts.

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    Thanks,
    Duncan

  2. #2
    Fellow Frogger! frog's Avatar
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    Hi Duncan, doesn't sound ideal. It's fine to experiment with spheres from different models but I'd definitely want the same damping and pressure on each side.

    On my 16V I've got Xantia double diaphragm front spheres on the front and the standard 16V spheres on the rear.

    Chris.

    Edit: Here's a thread on the 16V forum that is pretty informative:
    http://www.bx16valve.co.uk/forum/vie...38094716c10fca
    Last edited by frog; 23rd June 2012 at 01:26 PM. Reason: Added link

  3. #3
    UFO
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    And here is what can happen if you have the wrong spheres.


    http://www.youtube.com/watch?v=zcgQKMfzmlU
    Craig K
    2009 C5 HDi Exclusive

  4. #4
    Too many posts! JohnW's Avatar
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    Quote Originally Posted by frog View Post
    Hi Duncan, doesn't sound ideal. It's fine to experiment with spheres from different models but I'd definitely want the same damping and pressure on each side.

    On my 16V I've got Xantia double diaphragm front spheres on the front and the standard 16V spheres on the rear.

    Chris.

    Edit: Here's a thread on the 16V forum that is pretty informative:
    http://www.bx16valve.co.uk/forum/vie...38094716c10fca
    Forgive a small hijack here - how are the Xantia spheres on the BX? It's much lighter, so I guess they're pretty firm?

    Duncan, sounds bad service unless the spheres were wrong before and they've sorted it out for you. But you've obviously checked the numbers so not good for trust of service place..... I take it you've discussed this with the folk who did the repressurisation?
    JohnW

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  5. #5
    JBN
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    If I was in your situation, I would consider renewing all the spheres with the correct new ones. Then in a year or two, check their pressures and if any are doubtful, regas both of the spheres on the axle to their correct pressures.

    That procedure was done when I bought my Xantia. It does cost a bit first up, but combined with an LHM change and filter clean, it benchmarks your car. You then know how good it can be.

    John

  6. #6
    DS
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    There are many different types of sphere with many ID marks on them. It has become common for people to come to CCCNSW tech days to re-gas spheres only to learn they have dead/throw away spheres and all too often the wrong spheres in the wrong position.

    Spheres for the from axle have damping for front axle use and likewise for rear axle spheres. It is important. I would as JBN suggests start with NEW correct spheres rather than potential unknowns.

    There was a Xantia a few tech days ago that had four different spheres on the suspension and a DS recently thay had fronts on the rear and rears on the front!
    Citroen Car Club of New South Wales member.

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  7. #7
    1000+ Posts Ken W's Avatar
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    Hi John,

    The Xantia spheres fitted are from an SX, so 50 bar I think. The BX 16 valve spheres are lower pressure and higher damping than normal BX spheres so the Xantia ones seem to be somewhere between a normal BX and a 16Valve but al least they won't go flat in 2 years. They should last 10 years without a regas. This 'upgrade' was fitted by the previous owner on the recommendation of one of our local Citroen workshops.

    Cheers,

    Ken W

  8. #8
    Fellow Frogger! IE23's Avatar
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    Quote Originally Posted by JBN View Post
    If I was in your situation, I would consider renewing all the spheres with the correct new ones. Then in a year or two, check their pressures and if any are doubtful, regas both of the spheres on the axle to their correct pressures.

    That procedure was done when I bought my Xantia. It does cost a bit first up, but combined with an LHM change and filter clean, it benchmarks your car. You then know how good it can be.

    John
    I agree. Getting the spheres right is priority for your Citroen otherwise you may as well forget the Citroen and drive a pug or some other standard sprung car. One of the so called Citroen specialists had robbed a mates ds of its original spheres and put new ones on it. That ds was not a pleasure to drive.


    Adrian

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  9. #9
    BVH Roger Wilkinson's Avatar
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    Hello Duncan,

    You are right. What you have been given by this so-called "Citroen specialist workshop" is not good enough.

    Spheres have 4 essential characteristics that influence the suspension they offer: volume, gas pressure, bypass hole diameter and, criticially, damper configuration. Tables like the one you linked show the first three characteristics but not the last one. Your dodgy workhop has ignored the last two!

    When spheres were first introduced, for the DS (OK, 6H for you anoraks out there), dampers were removable and rebuildble. Their physical specifications were published and instructions for their overhaul produced. These dampers are little stacks of thin metal discs that sit either side of a holey centre body, held in place by specially shaped nuts. There are numerous versions of these dampers for different kinds of DS, with different thicknesses and diameters of discs, different configurations of holes in the bodies, different profiles of nuts, and different lengths of the studs that hold them together. This is not directly relevant to you, but I mention it to give you an indication of the complexity of damper design. In use, the discs deform away from the body and towards the nuts, allowing hydraulic fluid to flow through the damper to provide suspension movement. The bypass holes deal with only the smallest of bumps.

    Gradually, dampers became less replaceable and less rebuildable. Now they are riveted into the sphere neck and cannot be touched. Their specifications are no longer published. But one thing I do know from rebuilding DS dampers: front and rear ones are very different. I have run an XM for a short period on CX spheres, but I never swapped front and rear.

    I suspect your so-called "Citroen specialist workshop" (sorry, I can't help rubbing it in) has measured the pressure in the front speheres to be so low that it is close to the pressure that should be in the rear spheres (which run at a much lower pressure than the fronts). This ignores the fact that the bypass holes are a different size and the dampers are a different configuration. To be charitable to them for a moment, perhaps they were trying to save you money.

    I think the best thing to do now is to buy a new set of spheres. They are not expensive. That way, you know how it should ride. And next time don't leave it so long before you have the pressures tested.

    Roger

  10. #10
    Tadpole
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    Thanks for the feedback everyone,

    The technical background is very useful - I wasn't aware of the damper plates or how they worked in a D - learned something today... :-)

    Worst of it is, I got charged full-whack for the recharging. I've been using the chap for about 10 years, so to say it's disappointing to be taken for a chump is a bit of an understatement.

    The BX gets little use these days since we purchased a family truckster, (a diesel Mazda 6) so I didn't notice the ride degrading until recently - by which time it was too late to save one sphere.

    Monday morning I'll be making a phone call that one of us won't enjoy at all. If said Citroen specialist doesn't 'fess up and make good, I'll let you know.

    Thanks again everyone!
    Cheers
    Duncan

  11. #11
    Too many posts! JohnW's Avatar
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    Quote Originally Posted by duncan16v View Post
    Thanks for the feedback everyone,

    The technical background is very useful - I wasn't aware of the damper plates or how they worked in a D - learned something today... :-)

    Worst of it is, I got charged full-whack for the recharging. I've been using the chap for about 10 years, so to say it's disappointing to be taken for a chump is a bit of an understatement.

    The BX gets little use these days since we purchased a family truckster, (a diesel Mazda 6) so I didn't notice the ride degrading until recently - by which time it was too late to save one sphere.

    Monday morning I'll be making a phone call that one of us won't enjoy at all. If said Citroen specialist doesn't 'fess up and make good, I'll let you know.

    Thanks again everyone!
    Cheers
    Duncan
    "More sorrow than anger" for that call I'd suggest. He might need to know that one of his folk was careless and a bollocking won't help. If you "help" him out of the situation all might end well. Or not of course.

    Best of luck.
    JohnW

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  12. #12
    Too many posts! JohnW's Avatar
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    Quote Originally Posted by Ken W View Post
    Hi John,

    The Xantia spheres fitted are from an SX, so 50 bar I think. The BX 16 valve spheres are lower pressure and higher damping than normal BX spheres so the Xantia ones seem to be somewhere between a normal BX and a 16Valve but al least they won't go flat in 2 years. They should last 10 years without a regas. This 'upgrade' was fitted by the previous owner on the recommendation of one of our local Citroen workshops.

    Cheers,

    Ken W
    So the ride isn't too bad on the BX with the Xantia spheres then? Makes one think of using Xantia "comfort" spheres on the BX perhaps. The later composite membranes certainly last for a long time - will we have our BX in ten years? Perhaps but ten years is a long time. It's even a long time for the Xantia, even though it has only travelled 79,000 km.

    Thanks and please forgive hijack duncan16V.

    I agree with the advice to get a set of the right spheres for the BX with the issue. Use the cost unit "number of pints of Guinness" to justify the price perhaps.
    JohnW

    Renault 4CV 1951
    Renault R8 1965
    Renault Scenic 2005 (wife's)
    Renault Scenic 2007 (mine)
    Renault Scenic 2006 (daughter's)
    CitroŽn CX Pallas 1980

    National Co-ordinator, Renault 4CV Register of Australia

  13. #13
    Tadpole
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    Just a quick update: the spheres were put right with a smile and apology so all good!

    Thanks for your help.

  14. #14
    UFO
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    Quote Originally Posted by duncan16v View Post
    Just a quick update: the spheres were put right with a smile and apology so all good!

    Thanks for your help.

    Good news!
    Craig K
    2009 C5 HDi Exclusive

  15. #15
    Too many posts! JohnW's Avatar
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    Quote Originally Posted by duncan16v View Post
    Just a quick update: the spheres were put right with a smile and apology so all good!

    Thanks for your help.
    Best possible outcome. Excellent news. Thanks for closing it out.
    JohnW

    Renault 4CV 1951
    Renault R8 1965
    Renault Scenic 2005 (wife's)
    Renault Scenic 2007 (mine)
    Renault Scenic 2006 (daughter's)
    CitroŽn CX Pallas 1980

    National Co-ordinator, Renault 4CV Register of Australia

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