DS23 suspension spheres
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Thread: DS23 suspension spheres

  1. #1
    Tadpole
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    Default DS23 suspension spheres

    Hello all,

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    I replaced all 4 suspension spheres on 74 DS23 IE because they had 04 stamped on them. I found out the front spheres have 75 stamped on them, but all the documents I found said 59 bars should be the pressure.

    Did CitroŽn change the pressure somewhere or did somebody decide to use 75 - and for what reason?

    Thanks

  2. #2
    Real cars have hydraulics DoubleChevron's Avatar
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    Quote Originally Posted by stallhorn View Post
    Hello all,

    I replaced all 4 suspension spheres on 74 DS23 IE because they had 04 stamped on them. I found out the front spheres have 75 stamped on them, but all the documents I found said 59 bars should be the pressure.

    Did CitroŽn change the pressure somewhere or did somebody decide to use 75 - and for what reason?

    Thanks
    Sounds like it has Citroen CX throw away spheres fitted. See if you can chase up some rebuildable DS spheres!

    seeya,
    Shane L.
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    According to an official Citroen technical letter issued May 1975 the
    pressure for the welded spheres are as follows:

    DS front all types : 75 bar
    rear sedan : 35 bar
    rear break : 40 bar


    The pressures for the original rebuildable spheres are:

    front all types : 59 bar
    rear sedan: 26 bar
    rear break : 37 bar


    Volume of original screwed sphere is: 500cc
    Volume of welded sphere is: 385cc

    The increased pressure is to compensate for the smaller volume of the welded sphere so that when the car is at its normal ride height, the volume of compressed gas is the same.
    JohnW, UFO, forumnoreason and 1 others like this.
    Cheers,
    John T.

    54 TAV Legere; 61DS19 LHM BVH (son's); 71DS21 BVH; 73SM 3.0; 73SM EFI (Megasquirt); 73SM 3.0 (other son's)

  4. #4
    Tadpole
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    Quote Originally Posted by citroenthusiast View Post
    According to an official Citroen technical letter issued May 1975 the
    pressure for the welded spheres are as follows:

    DS front all types : 75 bar
    rear sedan : 35 bar
    rear break : 40 bar


    The pressures for the original rebuildable spheres are:

    front all types : 59 bar
    rear sedan: 26 bar
    rear break : 37 bar


    Volume of original screwed sphere is: 500cc
    Volume of welded sphere is: 385cc

    The increased pressure is to compensate for the smaller volume of the welded sphere so that when the car is at its normal ride height, the volume of compressed gas is the same.
    Thanks. It will have to wait until next replacement - not going to change it now.

  5. #5
    Real cars have hydraulics DoubleChevron's Avatar
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    Quote Originally Posted by citroenthusiast View Post
    According to an official Citroen technical letter issued May 1975 the
    pressure for the welded spheres are as follows:

    DS front all types : 75 bar
    rear sedan : 35 bar
    rear break : 40 bar


    The pressures for the original rebuildable spheres are:

    front all types : 59 bar
    rear sedan: 26 bar
    rear break : 37 bar


    Volume of original screwed sphere is: 500cc
    Volume of welded sphere is: 385cc

    The increased pressure is to compensate for the smaller volume of the welded sphere so that when the car is at its normal ride height, the volume of compressed gas is the same.
    Well I learnt soemthing today. I thought only the CX had 75bar spheres! I'm pretty sure the DS aftermarket spheres on my fathers DS23 were much lower than 75 (they were larger than CX spheres).
    'Cit' homepage:
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    Proper cars--
    '85 Series II CX2500 GTi Turbo I
    '63 ID19 http://www.aussiefrogs.com/forum/showthread.php?t=90325
    '72 DS21 ie 5spd pallas (last looked at ... about 15years ago)
    '78 GS1220 pallas
    '92 Range Rover Classic ... 5spd manual.

    Yay ... No Slugomatics


    Modern Junk:
    '07 Poogoe 407 HDi 6spd manual

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    I think you have the correct spheres for 1974 DS 23ie.
    When I first got my 12th month 1974 DS 23 ie it had welded spheres with no pressure at all. I found a set of screwed spheres and had them fitted with new diaphrams and nitrogen. I eventually came to realise that for post 11, 1974, welded spheres with firmer ride is correct.
    I lashed out on a set of 4 new welded spheres recently, and what an improvement!
    The car handles heaps better and is more comfortable with a bit firmer ride. Still floats but less bounce and pitching.
    David.

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    Quote Originally Posted by citroenthusiast View Post
    According to an official Citroen technical letter issued May 1975 the
    pressure for the welded spheres are as follows:

    DS front all types : 75 bar
    rear sedan : 35 bar
    rear break : 40 bar


    The pressures for the original rebuildable spheres are:

    front all types : 59 bar
    rear sedan: 26 bar
    rear break : 37 bar


    Volume of original screwed sphere is: 500cc
    Volume of welded sphere is: 385cc

    The increased pressure is to compensate for the smaller volume of the welded sphere so that when the car is at its normal ride height, the volume of compressed gas is the same.

    Just wanted to query the sphere volumes? I’ve seen three sizes of sphere referred to as:

    400cc for GS, Xantia, XM and all accumulator spheres
    500cc as fitted to very late DS, CX, some BX and as the hydractive centre spheres on XM
    700cc as fitted to DS, SM and the rear of the CX break (non-welded).

    I’ve never quite believed these round numbers or seen a Citroen document confirming them - would be interested to know if there is one?

    The spring energy in the sphere is a function of the pressure volume product. If you keep the pressure multiplied by the volume constant, the suspension behaviour will be the same. So if a 500cc sphere of 40 bar is needed but only a 400cc sphere is available then inflating it to 50 bar will do the same job (20 bar-litres of energy stored in the sphere). Of course the damping behaviour is a function of the centre hole size but that can be easily checked with a set of small drills.

    This is a useful reference for sphere pressures if you’ve not seen it before http://oto.to/schematy/citroen_kule.pdf
    JohnW likes this.
    Cheers, Marc.

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    That's a very useful chart Marc, yesterday I took the DSpecial out for it's first spin in what 5 or 6 years and I got down to the inspection mechanic and smoke was coming out of the bonnet! WT... as I lept out to open the bonnet and my glasses fell off and a lens popped out. Smoke was wafting off the exhaust. I peered in and thought the sphere was leaking from the centre thread of the screw type sphere. So I thought stuff it I'll drive it back hang the consequences. Get back, more smoke. What had happened was I had cleaned and oiled the air filter mesh again and even though I thought I had drained it pretty well some dripped out of a hole at the bottom of the air intake tube, there are a couple along it and the oil had landed on the sphere and then the manifold. Thinking the sphere was dodgy I had contemplated chucking on an old Xantia sphere in the interim, having that chart would have allowed me to pick which one to put on. Fortunately it never had to be enacted as I figured out the grief. Apart from that the old girl moved along reasonably well, needs a bit more fine tuning and make sure the air filter is sorted before I drive it again. ha ha.

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    While not being one whishing to get into an argument I must take exception to a statement of Marc,s. In my view if a sphere is correctly inflated the softness (or hardness ) of the suspension is only a function only of the remaining volume of gas in the sphere thus a smaller sphere will produce a firmer suspension. Taking Marc's argument to its logical conclusion a 50cc sphere inflated to 400 bar would do the same job???
    Woody

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    Default "Here's one I prepared earlier...."

    Marc quoted:
    " 700cc as fitted to DS, SM and the rear of the CX break (non-welded).
    Iíve never quite believed these round numbers or seen a Citroen document confirming them - would be interested to know if there is one?
    "

    I've just dismantled this sphere, a two piece DS front with fixed damper, which had no pressure in it. To say the diaphragm has failed would be a tad restrained!

    The reason for the post, however, is that a measurement of diameter of the unit reveals the inside to be 11cm diameter. A bit of memory prodding reveals the formula for volume of a sphere to be 4/3 x pi x R^3. Some work with a calculator, because doing cubes in my head is way back in the past, reveals (4 x 3.14159 x 5.5 x 5.5 x 5.5) / 3 resulting in a volume of 696.909382 cc. I imagine that the neck region might add a couple more cc so 700 is close enough to being a correct round figure for me.

    That's enough pedantry for one day. I need my lunch!

    Cheers, Pottsy.
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    Quote Originally Posted by brian woodcock View Post
    While not being one whishing to get into an argument I must take exception to a statement of Marc,s. In my view if a sphere is correctly inflated the softness (or hardness ) of the suspension is only a function only of the remaining volume of gas in the sphere thus a smaller sphere will produce a firmer suspension. Taking Marc's argument to its logical conclusion a 50cc sphere inflated to 400 bar would do the same job???
    Woody
    Hi Brian

    Spheres of different volume can be used to do the same job, provided the stored energy as a compressed gas inside them is held constant. They are basically pressure vessels that store energy behind the diaphragm. Fundamentally the stored energy is the gas pressure P multiplied by the sphere volume V, so two different size spheres will behave similarly provided PV = constant. That translates to raising the charge pressure of the smaller volume sphere, so that it’s PV equals the PV of the bigger volume sphere.

    I think we’ve only got 3 different size spheres from Citroen to consider which limits the options, and all of this is only relevant if one’s stuck in not having the original size sphere to hand. However there are hydropneumatic accumulators available that follow the original Citroen invention which can be charged to pressures of up to 400bar and some are very small 50ccs or less, e.g. http://www.hydroleduc.com/images/lin...uc_accu_en.pdf

    Anyway I don’t want to bang on about this, I’ve just found it useful over the years as I seemed to acquire a lot of 400 and 500 cc spheres from CX and XM - mainly from a series of XM’s that packed up in succession! One thing that I found an XM was good for was it’s centre spheres - they are 500cc, and I use them as accumulator spheres on my car’s, charging them to 75 bar which gives about 50% more stored energy and slows down the cycle time of the hydraulic pump.
    JohnW and Vincenzo like this.
    Cheers, Marc.

    1987 CX GTi T2 Maikonics
    1972 SM 2.7 carb
    1972 DS21 EFI

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    Hi Marc, I am not taking issue with your physics here, what I am saying is that since the dimensions of the Piston and cylinder which displace fluid into the sphere are fixed then consequently the is only one optimum size of sphere. (excuse the tautology).
    Woody

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    Quote Originally Posted by David S View Post
    The hole in the middle is a good indicator of what the sphere is for but is really a last resort bypass and if you take the dampers out of later spheres, you see it is only that size for a short distance before opening out to a larger diameter. Most of the fluid passing by is via the holes in the plate hidden by the little discs and their arrangement and number are important in setting the damping.
    The "by-pass" holes are really there so the suspension can absorb minor wheel movement - movement that normally would not provide sufficient fluid velocity to force it through the actual dampers. One of the reason that folks feel the fix shocks provide a "harder" ride than the older, rebuildable units, is the size of those holes. The older style used 2.0 bypass holes front and back. The fixed units (on D sedan) are 1.8/1.6 front and back. OTOH the later style resist body "roll" better in hard cornering.......

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    Quote Originally Posted by Caisson View Post
    I think you have the correct spheres for 1974 DS 23ie.
    When I first got my 12th month 1974 DS 23 ie it had welded spheres with no pressure at all. I found a set of screwed spheres and had them fitted with new diaphrams and nitrogen. I eventually came to realise that for post 11, 1974, welded spheres with firmer ride is correct.
    I lashed out on a set of 4 new welded spheres recently, and what an improvement!
    The car handles heaps better and is more comfortable with a bit firmer ride. Still floats but less bounce and pitching.
    David.
    David,

    How do you know what month your car was made?

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    Hi Stallhorn I only just saw your last post, sorry.
    No I don't know the actual build date . The the engine number on the compliance plate indicates a 1974 model year car,
    but the Citco applied date is December 1974.
    I take this to indicate that the car was amongst the last batch imported to Australia and probably sold in 1975. Unfortunatly the Citco sales records do not include D"s sold from the second half of 1974 so I havent been able to find out who bought the car new.
    My theory is that the car is a 1975 model year that had a DX5 engine with a 1974 engine number fitted at the factory .
    Maybe someone with encyclopedic memory or better still, access to technical details or photos may know what suspension spheres 1975 cars had originally.
    I believe they at least had a welded main accumulator.
    Incidentally we had a 1975 DSpecial that had 5 welded speres also. Obviously not the original items, but could be the original type?

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    Quote Originally Posted by Caisson View Post
    I think you have the correct spheres for 1974 DS 23ie.
    When I first got my 12th month 1974 DS 23 ie it had welded spheres with no pressure at all. I found a set of screwed spheres and had them fitted with new diaphrams and nitrogen. I eventually came to realise that for post 11, 1974, welded spheres with firmer ride is correct.
    I lashed out on a set of 4 new welded spheres recently, and what an improvement!
    The car handles heaps better and is more comfortable with a bit firmer ride. Still floats but less bounce and pitching.
    David.
    I believe that the very last of the DS (1975 year) did have non split spheres. I have a Ď75 build DS, (according to the chassis numbers listed by John Reynolds in The Original Citroen DS) although the original purchase documents say it is a Ď74 model to sneak it into Ď74 ADRs. The car was one of the last batch of DS to come to Australia. When I bought my car it had one piece spheres and I considered them to be incorrect and to have been fitted by a previous owner. But in conversation with Arthur Greaves (now deceased) who also bought a car from this last batch he assured me that his, and therefore mine, were fitted with non split spheres. Not that I thought, prior to my conversation with Arthur, that the spheres on my car when I bought it were the original spheres but I thought that previous owners had moved away from originality. The story goes that because the CX was in production by this stage and they had run out of split spheres the factory then bunged whatever they had on the last of the DSs. There is some credence to this story in that my car has the aircon front bumper but no aircon and is not fitted with a 3 belt pully. Anyhow I have since replaced my single piece spheres with split spheres, so Iím the one who has moved away from originality, but I do prefer the softer ride. And it is noticeable. Iím happy with the handling as Iím not a spirited driver on winding roads.


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    Quote Originally Posted by Dave Rogers View Post
    I believe that the very last of the DS (1975 year) did have non split spheres. I have a Ď75 build DS, (according to the chassis numbers listed by John Reynolds in The Original Citroen DS) although the original purchase documents say it is a Ď74 model to sneak it into Ď74 ADRs. The car was one of the last batch of DS to come to Australia. When I bought my car it had one piece spheres and I considered them to be incorrect and to have been fitted by a previous owner. But in conversation with Arthur Greaves (now deceased) who also bought a car from this last batch he assured me that his, and therefore mine, were fitted with non split spheres. Not that I thought, prior to my conversation with Arthur, that the spheres on my car when I bought it were the original spheres but I thought that previous owners had moved away from originality. The story goes that because the CX was in production by this stage and they had run out of split spheres the factory then bunged whatever they had on the last of the DSs. There is some credence to this story in that my car has the aircon front bumper but no aircon and is not fitted with a 3 belt pully. Anyhow I have since replaced my single piece spheres with split spheres, so Iím the one who has moved away from originality, but I do prefer the softer ride. And it is noticeable. Iím happy with the handling as Iím not a spirited driver on winding roads.


    Sent from my iPad using Tapatalk Pro
    Thanks Dave for confirmation of the later D sphere question. I will be able to more confidently defend the point against doubters now. I have heard that the later 2 piece spheres with clip in dampers have the same springing rate as the CX type spheres. When I was looking at 1 piece spheres on the spherE shop site, I had the option of standard D spheres or softer " comfort spheres" for a few Euros extra. David.

    Quote Originally Posted by Caisson View Post
    Hi Stallhorn I only just saw your last post, sorry.
    No I don't know the actual build date . The the engine number on the compliance plate indicates a 1974 model year car,
    but the Citco applied date is December 1974.
    I take this to indicate that the car was amongst the last batch imported to Australia and probably sold in 1975. Unfortunatly the Citco sales records do not include D"s sold from the second half of 1974 so I havent been able to find out who bought the car new.
    My theory is that the car is a 1975 model year that had a DX5 engine with a 1974 engine number fitted at the factory .
    Maybe someone with encyclopedic memory or better still, access to technical details or photos may know what suspension spheres 1975 cars had originally.
    I believe they at least had a welded main accumulator.
    Incidentally we had a 1975 DSpecial that had 5 welded speres also. Obviously not the original items, but could be the original type?

    Sent from my LG-K520 using aussiefrogs mobile app

    Sent from my LG-K520 using aussiefrogs mobile app

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