DS spheres

[Budge]

I know the pressures in DS spheres are different for front and rear, but are the dampers inside the same? In other words are they interchangeable if gassed correctly?

Related to this, am i right in saying that front sphere pressures changed round about 68/69? being a slightly softer 'comfort' ride before that and a slightly harder ride after? If so, what were the different pressures please? And again - were the dampers the same before and any such change?

Any advice welcomed

Budge

 

[Citroenfan]

I know the pressures in DS spheres are different for front and rear, but are the dampers inside the same? In other words are they interchangeable if gassed correctly?

Related to this, am i right in saying that front sphere pressures changed round about 68/69? being a slightly softer 'comfort' ride before that and a slightly harder ride after? If so, what were the different pressures please? And again - were the dampers the same before and any such change?

Any advice welcomed

Budge

Not really interchangeable First off the pressures are 59 bar front (approx 890 psi) and 26 bar rear (approx 380 psi) where the same from the DSs introduction to end of production. The actual damper valves also have major differences. Shimming (those little discs that control the movement of fluid through the valve body under normal to sever wheel movement) is completely different front and rear as well as the actual shape of the dampers bodies. Additionally the small hole in center of the 'fixed' shocks are different front/rear (D units are 1.80mm/1.60mm). The older style units with the rebuildable shock bodies are 2.0mm front/rear - the main reason they ride better over small undulations. Those 'by-pass' holes replaced the very early solution to small wheel movement that factory initially used - a 0.03mm shim. The 'bypass' holes/discs allow the suspension to react quite nicely to small wheel movements that do not produce sufficient 'hydraulic force' to move fluid through the main valve body set up. IOW if they were not there you would feel every bloody tar strip/road patch . Keep in mind that the Cit system greatest strength is the ability to absorb large wheel movements - its greatest weakness is small movements. Those bypass holes very elegantly solved that latter problem. The downside is increased body roll. As time went on with later models - the factory went to great lengths to reduce body roll without compromising the legendary Citroen ride.

When the factory introduced the fixed shock units the main reason for the noticeable increase in ride 'stiffness' was the reduced diameter of those 'bypass' holes. They, again, change the ride characteristics in the mid 70's by increasing, a bit, the damping value over larger wheel movements with a change to the damper valves and shimming.

 

[Budge]

Thanks for the comprehensive reply. I'm sure I read that front sphere pressures changed - and I think Darrin here in the UK offers 2 different pressures? I'm beginning to see that it's actually a combination of factors that affect the ride. Maybe is two 'hardnesses' that he offers

I want to find some early spheres with removable dampers so that i can strip and clean them with ultrasonics - to get the best ride quality I can. Sounds like I need to look out for a pair for the front and a slightly different pair for the rears?

I 've picked through your reply to pull out the key bits.

- The non-"fixed shocks" are the earlier removable dampers - yes? And these had 2.0mm holes front and rear.
- Front and rear shocks/ dampers bodies were different shapes for front and rear, even though sphere bodies are the same and regardless of whether the damper is removable or fixed into the sphere body.
- Not sure what the bypass holes are? I suspect you mean the 2.00mm (or 1.8mm/ 1.6mm if fixed) hole in the centre of the damper valve?

I picked up an original copy of Manual 844 "Hydraulic Course Notes" and should payer attention to it!

Budge

 

[faulksy]

Removable damper spheres are becoming hard to come by in reasonable nick. Damper assemblies more so should you need a replacement.

Green and red fluid spheres and dampers are physically the same and can be swapped provided the rubber diaphragm has been replaced to suit the fluid in you car. Mixing the two up will result in a melted diaphragm.

front and rear damper assemblies have the same physical dimensions and can in fact be screwed into any sphere. What distinguishes a front damper from a rear is the number, thickness and location of the shims in the assembly. The bottom nut of the assembly has different markings machined into the face to identify the 3 different types, front, saloon rear and safari rear. From memory manual 814 shows the differences in shimming and identification but you may need an earlier manual.

 

[mberry]

I found this handy reference useful. Have a .pdf version of a higher resolution if required, unfortunately forum doesn't accept .pdf.

 

[David S]

That is an early aluminium regulator shown in the diagram should anyone be unsure why it doesn't look like the steel unit they have in their D and would be almost the same as used right through to the last Xantia/XM.

Is there a supply of new shim washers out there? Both shim material and thickness would play a part in how it behaves and how long it lasts.

 

[Budge]

Thanks for all the extra info. i'm soaking it all up! handy little diagram that - probably sufficient quality to print out as an A4.

So can the early dampers be removed and taken apart (to clean any gunk off the shims?).

 

[Citroenfan]

Thanks for all the extra info. i'm soaking it all up! handy little diagram that - probably sufficient quality to print out as an A4.

So can the early dampers be removed and taken apart (to clean any gunk off the shims?).

Budge - to clarify a bit more. The actual damper 'nuts' have, basically, three different 'shapes' or curvatures depending on their placement on the cars and/or model (sedan/break). And they did change a bit over the production run of the cars. The upper nuts - the ones on the compression side as one goes over a bump - had the same profile for all models - front or rear. What varied was the thickness and number of shims used to control fluid flow. The bottom nuts (rebound side) for sedans were the same as top on the front. The rear sedans and breaks had specific nuts for the rebound side. And those did change for the Breaks over the years being designated with the stamp "AR1 -AR2 - AR3" with the AR3 ones the last used. The bottom nuts for the rear Sedans have a thin, machined edge, on the outer rim to make identification easy. See the attached jpeg image.

The 'bypass' hole for the rebuildable units is machine on the outside edge of the shock body - which you can see on the attache image. FWIW I use, on my two D's the "heavy duty" arrangement. As to actual spheres - I am sure someone in your area has access to the two part rebuildable units. If you can locate some you will also need to get diaphragms. Available from most of the usual suspects. For LHM you want the semi-clear Desmopan material. For LHS cars you would need to source EPDM rubber molded units. I know that Andre Pol (Citroen Andre) can source them. Additionally you need to be able to fill, pressurize, them. That requires either the Technosir system, which uses a special 'Schrader' type valve or access to a stand alone unit.

Steve

 

[Budge]

Thanks Steve. It's starting to make sense now. I will probably get someone else to supply or build and gas the spheres, so i will either need to provide the parts for building or as like-for-like part exchange.

 

[Don B. Cilly]

You may want to check the Tecnosir store, they sell spheres, membranes, and recharging equipment.

 

[Budge]

Thanks Don. I'll have a look

 

[Rally]

I know the pressures in DS spheres are different for front and rear, but are the dampers inside the same? In other words are they interchangeable if gassed correctly?

Budge

In the days of CX being a daily driver , many cars would come to the service dept with hard ride due to four under pressure spheres, a common practice in many workshops was to swap the fronts to the rear ( the pressure was now about correct for rears ) and fit a new pair to the front.
Impossible to pick the difference on the road , nobody ever complained and a much cheaper repair.

 

[Roger Wilkinson]

If you believe the manuals, the discs are conical and you are supposed to rub them on fine emery paper to find the concave side and ensure you fit them the correct way. In practice, on inspection of used ones I have found they seem to have a single fold line in them and that's all.

Roger

 

[DoubleChevron]

In the days of CX being a daily driver , many cars would come to the service dept with hard ride due to four under pressure spheres, a common practice in many workshops was to swap the fronts to the rear ( the pressure was now about correct for rears ) and fit a new pair to the front.
Impossible to pick the difference on the road , nobody ever complained and a much cheaper repair.

That is so wrong .... What workshops were doing that The valves are VERY different front to rear! I can understand the reason for doing it ... have probably done it myself too The rear ones are almost always dead beyond regassing as the sphere membrane hits the sharp bit on the filler plug when the gas charge is low.

Here's some DS sphere valve stuff here;

http://www.aussiefrogs.com/forum/citro%EBn-forum/101810-sphere-identification.html

seeya,
Shane L.

 

[Budge]

FWIW I use, on my two D's the "heavy duty" arrangement.
Steve

Still soaking all this in...... Steve, i saw reference to 'Heavy duty" set up in the PDFs you attached. I looked back over Manual 814 (1974) and manual 518 (1966) and the only shimming both manuals show seems to equate to this "heavy duty" set up. So what is the source of the "normal" set up in your PDF please? Does "heavy duty" equate to "stiffer" or just "hard wearing"/ "longer life?

I've just checked. Darren sells cheap one piece spheres with either a "standard" or 15% softer "comfort" ride. He also "fixed" damper split spheres - but where the damper has then been removed and replaced. These are apparently then set up to give the pre-December 1970 "softer ride". So how is this likely to have been achieved? Is is simply that the bypass has been drilled out to 2.0mm, or will it also be about a different combination of shims? As above Manuals 518 and 814 don't seem to distinguish between soft and hard rides?

 

[Budge]

The 'bypass' hole for the rebuildable units is machine on the outside edge of the shock body
Steve

And another question Steve..... I couldn't work out where the bypass was on your attachments - sorry! Ii followed the old Sphere thread where someone had a 'mystery' sphere - possibly from an SM (so a later sphere with fixed damper) with a 1.4mm bypass and was told they could drill it out to 1.8mm to turn it into a later DS front sphere. Shane (for it was he), said he would look to drill out the centre bypass hole. So if it's a fixed damper sphere, then the bypass is both visible AND accessible from the end of the sphere? So is it just the hole down the centre of the damper? One of the angle lines/ holes/ passageways that i think i can see in the diagram taken from the manual? Or is it actually in the green outer shell of the sphere??? I'm confused between 'damper' and 'shock body'. I'm not planning to drill out anything myself. i'm just looking to get a definitive set of identifying features for front/ rear split spheres with removable dampers from between 1963 - 1970 as I'm on the look out for a set.

 

[David S]

It is possible to remove the dampers from the later spheres. If you look at an accumulator, you see there is a ridge around the threaded part and that is pressed over to retain a damper assembly. If you take one out, you will see that the back end of the central bypass hole is much larger than the hole you see when it is fitted in the sphere. I'd think it wouldn't be too hard to modify the end of the sphere and make the damper removable like the ones with a retainer ring. They are different to the early type shown in the pictures above in this thread where the central bolt screws into the bottom of the sphere.

Here is something of interest from FrenchCarForum:
https://www.frenchcarforum.co.uk/forum/viewtopic.php?t=41030
It shows a picture of a sphere with the damper retained by the threaded ring.

 

[Budge]

A little knowledge is a dangerous thing.... I'm now thoroughly confused! I'd welcome any thoughts on any of the attached images as I'm clearly not getting it.....Images show three different kinds of split spheres that i have, a couple of images from the web, and an extract from 814 relating to electronic ignition cars. not sure if it's equally applicable to carb cars (I have a carb DS21)

 

[Citroenfan]

A little knowledge is a dangerous thing.... I'm now thoroughly confused! I'd welcome any thoughts on any of the attached images as I'm clearly not getting it.....Images show three different kinds of split spheres that i have, a couple of images from the web, and an extract from 814 relating to electronic ignition cars. not sure if it's equally applicable to carb cars (I have a carb DS21)View attachment 95871View attachment 95872View attachment 95873View attachment 95874View attachment 95875View attachment 95876

Budge,

Not really all that complicated - Spheres supplied up to around 1968-1969 had rebuildable shock dampers installed. IOW one could remove them, disassemble, and put in fresh shims. IIRC with the introduction of the first IE cars is when the riveted damper bodies were introduced. And the first of those used a retaining ring to hold the riveted damper body in the neck of the sphere. Those dampers were not designed to be taken apart and 'refreshed'. You just bought new units and inserted into the neck of the spheres. After 12/70 all cars ,IIRC, came equipped with the damper body permanently affixed in the neck of the spheres. Do keep in mind regarding dates - I am in US - and we did not always get things in the same 'time line' as the rest of the world . And I do not remember the US getting any of the cars with replaceable riveted shocks - though we could well have.

Bottom line is this - the most 'comfortable ride' with a D will come with older style spheres (the ones with the removable and rebuildable) damper bodies. They are quite characteristic as the damper valve/shims are held together by two large nuts on either side of the actual valve body with a threaded shaft in the middle. And as previously pointed out those 'nuts' are an integral component of the fluid control valve. Depending on placement (front/rear/top/bottom placement) they had/have specific curvatures on the shim side of the nuts. And those curvatures did change over time depending on car model. The other thing to keep in mind with the rebuildable units is the torque used when re-assembling them. They are torqued, first on the bench, to 15 ft/lbs. When placed in the sphere they are torqued to only 12 ft lbs .

Hope this helps to clear up the confusion or at least some of it

Steve

 

[Budge]

Thanks Steve. yes - that's the conclusion I was reaching. Thanks for confirming.

I think I've got some split spheres with fixed valves that have been gasses for the opposite/ wrong ends of the car. i will search out some removable types, but 'Plan B' is that my current ones can be taken apart and put back together to make a set.