Spheres canundrum

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alan s
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Spheres canundrum

Post by alan s »

A while back a guy contacted me & said he's been for a drive in a BX 16V & it handled like it was dancing on jelly.
It seems that he had owned a Peugeot & was looking to make a change & this was as close to what he had that he could find. I went through the motions re tyres & spheres & he was so sure that everything was OK as he knew the mechanic who serviced the car & he would know what he was doing.
I tried to tell him I also knew the same guy & didn't think he was all that crash hot....anyway, a few weeks later the car turned up at an Auction after an underbonnet fire & we bought it. In the process of presently doing a refurbish job so today I took the spheres off as they appeared to be either new or almost. When I looked at them I find they are 500cc instead of 400
pressure is about right according to the outside but the bore size is 2.6 instead of 1.2
I have fitted them to my 16V but as yet haven't taken it for a spin but I think I know how it's gunna ride...YYYEEEEHHHAAAAaaaaaa!!!! ride 'em cowboy!![:I][}:)][:o)][:D][B)]
I've checked all the lists I've got & for the life of me I can't find anything that matches the description.
Anybody any clues where they may have come from???
Alan S [B)]
alan s
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Post by alan s »

Just took the car for a short run & I do mean short....what a thrill and a half that was!!
It now is no longer stable above 90kph and when driven in a (hopefully) straight line it ducks & dives all over the road. The steering instead of feeling direct & responsive feels "light" as though it is barely touching the road & in fact when you hit any slight dip in the road, you' swear this was the case.
Just thought I'd post these details as we often have people asking questions about the handling of Citroens & I often get the impression that when told of the difference a set of spheres make, think we are doing a spot of leg pulling or exagerrating.
Would still like to know what these spheres are supposed to be for so I know who to give them to...alternative #2 I suppose would be to find the biggest enemy I know who drives a Citroen as a peace offering.[}:)][:o)]
Alan S
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AndersDK
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Post by AndersDK »

Hi AlanS -
To your description it's likely to be the CX "comfort" spheres manufactured by thoughtless companies.
Untill recently when I had the sphere valve discussion with AlexX here onboard, I also thought that a larger bore would increase the ride comfort. But AlexX lightened up the secrets to me of the sphere valve's function thus telling me a larger bore is prone to give instability.
If you think of your car's behaviour, then add the fact that a CX is much heavier at front, I think in fact these spheres may give a somewhat better ride comfort on a CX....
....but also I think you'll still pay with CX instability at moderate to high speed.
alexx
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Post by alexx »

Alan, did you measure the central bore diameter, or it was a number mark on it? According to spreadsheet on www.bx.citroen.org, this number doesn't correspond to bore diameter (if my memory serves me right, my mechanic once mentioned mark 0-6 for BX16 front spheres, as in that spreadsheet).
If central bore size was really 2.6 mm, it was to be expected that the car would float all over the road. Every suspension setup is thoroughly tested by the factory, to achieve a good compromise between comfort and roadholding over all road conditions, so it can't be expected that shortcomings like bigger central bores will do the trick.
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Post by Dave Burns »

Hmm.....is it possible that the number stated for the damping orifice of 2.6 refers to the area of it rather than its diameter, if that was the case then the actual diameter of the hole would be just over 1.8mm
Dave
alan s
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Post by alan s »

I was basing it on what is stamped on the base (the silver part near the hole) but it looks pretty massive alongside the original.
The suggestion has been made elsewhere that they possibly could be from something like a Rolls or Merc which is feasible in this case as the repairer also used to regas spheres from Rolls (I was there one day when he was doing one a few years ago) but when I saw Roller spheres, they were chromed but someone may have brought a cheaper version out. I know the ones used in some Mercs were there in place of or additional to the shock absorbers but these cars still had tin springs.
Another theory I had was I wondered if perhaps a sphere company in its wisdom had produced a sphere for the rougher riding yet higher performing CXs or similar. The idea to give softer ride at slow speed/rough roads whilst reducing body roll on higher speed corners. I made this guess based on the fact that the amount the car can be pushed down is radically reduced due to the lower nitro pressure.
Given the relatively small number of Hydraulic Citroens sold in this country and the overall lack of general knowledge as to how they operate, you'd still have to wonder how a mix up like this could happen here.[}:)][:p]
Incidentally I took one of my sons for a run in the car yesterday & he thought I was deliberately making the car dive around, so I took my hands off the wheel; within about 3 or 4 seconds, the car dived into the onncoming traffic lanes, I straightened it up, let go & just caught it before it speared off the road on the other side.....that's how bad it is to drive.
Alan S
Alan S
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Post by alan s »

P.S. to above.
Just took the car for a short hike taking one of the boys to school & returned via a dirt road.
Approaching, I had to brake fairly heavily and another thrill, it started to fishtail slightly; I was still on the bitumen at this stage.
Upon driving on dirt, I found the ride better than with correct spheres although not up to CX standard (those things do tend to spoil you for everything else though) and was as controllable at 90 kph on dirt as it was on bitumen but from there on, the trade mark instability gave the impression that it wouldn't take a lot of encourageing to have you shaking hands with the tail pipe [:D][:0][}:)][:I]
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AndersDK
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Post by AndersDK »

AlanS -
- sounds exactly like the way my former (rusty) BX16 performed in next-highest on dirt tracks with nice potholes. It was allways an astonishing pleasure trying this. At a certain speed (some 50kph) it allmost "sailed" over the road - well lots of banging and noise from suspension - but fully controllable and flying literally. That's how good spheres, with damper valves calibrated for the actual vehicle should perform on a hyd Cit [:)]
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Post by rabenson »

It's worth remembering that a car suspension is effectively a second order mass/spring/damper system in control terms. Every component contributes toward the tuning of this system and by unwise selection of parameters, it is possible to get resonances at particular frequencies, which can lead to the sort of behaviour that you have described. Fun to simulate in the lab but I bet less so on the road...
alan s
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Post by alan s »

.......the continuing saga.........
Here's the numbers on the spheres.
In black:- 96024567
9-189 AS
Stamped alongside the black letters:- U
M93
That give anyone any clues???
Alan S[?][?]
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Post by alexx »

According to www.bx.citroen.org, those are rear spheres for BX TRS/TZS/TZI estate, 500 ccm, 40 bar, bore 1.1 mm. According to that page, it's a Jpn part number, while Eu part number for the same spheres is 96-024-566. Other details about the damper are not specified.
The second number (9-189) was newer mentioned in any sphere specification. I suppose it could be a production date in the format y-ddd, meaning 189-th day of 1999. Well, not quite sure about that, but Xantia I've test driven previous month was produced at the beginning of '98, and front spheres had something like 8-010 and 7-360 stamped, so ...
Alex
alan s
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Post by alan s »

Thanks Alex,
We're starting to get closer by the looks. Everything stacks up bar the bore size; 1.1 against 2.6.......that seems to be still the mystery; "heavy duty" rear spheres for an Estate for those wanting to carry heavy loads perhaps?
What do you think??
Alan S
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Post by alexx »

Since estate rear spheres have 500 instead of 400 ccm, I expect that the damper is also different, because of lower spring rate (when the car is empty) and higher load. According to mentioned page and my remembering from the garage, spheres for BX16 hatchback have mark 2-5 on the damper, so 2-6 here makes sense. Also, according to that page, rear spheres for hatchback have 4 U-type rebound discs (0.66 mm in total). On estate spheres, this package is probably thicker, because of lower spring rate and higher load (maybe 3 x U + 1 x A or 2 x U + 2 x A or even more). Take a look.
Anyway, it seems that rear spheres mounted on the front aren't really a good solution, are they?
alan s
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Post by alan s »

Thanks Alexx,
You're a legend mate; looks like at last it's been answered..all I have to do now is either find someone with a BX Estate (rare commodity in Australia; how stupid's that?...they popularised this type of vehicle) or buy one myself.
Thanks again...problem solved!!
Alan S
Jon

Post by Jon »

Hmmmmm
Well are you going to put the right ones on then Alan?
Want me to get you some 16v fronts, or follow the XMV6 route........................
:-)
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