Accumulator sphere

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splat
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Accumulator sphere

Post by splat »

I've just had a new accumulator sphere fitted by a garage. There's a label on the sphere which reads "Xantia/XM rear suspension accumulator" which sounds a bit weird to me.
Does anyone have any thoughs on whether this sounds like it's the correct sphere?
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AndersDK
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Post by AndersDK »

3 options from your workshop :
1) the mechanic grabbed the nearest sphere from the shelf where the package read the word accumulator
2) the mechanic is a zombie
3) the workshop uses the same type sphere for all accumulator applications - to keep down stock
Either option - the fitted sphere will work OK and in no way degrade or harm your car. It's just not the correct type pr partslist.
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Post by Chrispy »

The only difference between a normal sphere and an accumulator sphere is that the acc one doesn't have the baffle in the entrance hole to slow down the flow of LHM. This gives the damping effect. Without this the sphere's would bounce like when knackered. I'm not sure if there's any difference between the rear sphere and the acc one, but they might have different pressures, one perhaps being 'softer' than the other. Otherwise I'll bet there's nothing in it.
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Post by Kowalski »

Is the pressure on the anti-sink sphere the same as an accumulator?
If they are it'll do no harm having the wrong sphere there, they do much the same job. If the sphere has a lower pressure it'll perform like an accumulator that has lost a bit of gas, i.e. not ideal but better than a completely flat sphere.
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Post by Stempy »

Rear anti sink 'accumulator' is 50 bar, front accumulator is 62 bar so fitting the rear one in the front will be like having worn front one in there.
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Mandrake
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Post by Mandrake »

<blockquote id="quote"><font size="1" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by splat</i>

I've just had a new accumulator sphere fitted by a garage. There's a label on the sphere which reads "Xantia/XM rear suspension accumulator" which sounds a bit weird to me.
Does anyone have any thoughs on whether this sounds like it's the correct sphere?
<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">
No it's not...
Sounds like an anti-sink sphere. (Which technically speaking, is a rear brake accumulator) Ask your garage to redo it, and put the correct one on this time [:D] There is no reason to accept them putting on the wrong sphere and charging you for the priviledge...
If they complain that its near enough, or if they are unaware of their mistake, then considering finding a different garage for your next work, as who knows what other mistakes they may make or shortcuts they may take...
Regards,
Simon
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Post by JohnT »

For all that has been said.... if you do not have the correct sphere on your car it will not work correctly no matter what your point of view is. The internal pressures are critical, that is why a worn sphere has such an effect on the suspension ( hard) , so conversley an increased pressure will give a wallowing effect. Get them to do the job correctly, the resulting handling is irresponsibility in the extreme. If I changed your shockers on another 'normal' car for the wrong ones would you accept that?
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Mandrake
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Post by Mandrake »

<blockquote id="quote"><font size="1" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by JohnT</i>

For all that has been said.... if you do not have the correct sphere on your car it will not work correctly no matter what your point of view is. The internal pressures are critical, that is why a worn sphere has such an effect on the suspension ( hard) , so conversley an increased pressure will give a wallowing effect. Get them to do the job correctly, the resulting handling is irresponsibility in the extreme. If I changed your shockers on another 'normal' car for the wrong ones would you accept that?
<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">
I agree about "near enough" not being good enough, but bear in mind we're talking about the accumulator sphere here, so it's not going to directly affect the ride...a suspension sphere on the other hand....
Regards,
Simon
splat
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Post by splat »

Thanks for all the advice.
So the concensus is that a "rear suspension accumulator" is actually an anti sink sphere, which has a lower pressure than a 'main' accumulator?
Would the anti sink sphere definitely fit in place of the accumulator (doesn't it have an extra pipe connected)?
Could someone explain why the anti sink sphere is called the anti sink sphere, when as far as I understand it doesn't have anything to do with the car not sinking?
I pretty much have to stick with the garage I use as they are the only place round here that have even the slightest clue about Citroen suspension. Nearest main dealer is 50 miles away and probably too expensive/too incompetent anyway.
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Post by FrenchLeave »

Quote: "Could someone explain why the anti sink sphere is called the anti sink sphere, when as far as I understand it doesn't have anything to do with the car not sinking?"
The rear brakes get their pressure supply from the rear suspension, this has the advantage that the maximum rear braking effort is proportional to the load on the rear wheels. For cars without anti sink there is also the advantage that in the event of total hydraulic failure, the volume of fluid under pressure in the rear suspension system acts as an emergency supply for the rear brakes. This is sufficient for several brake applications and is certainly enough to bring the vehicle safely to a stop.
With cars fitted with anti sink, in the event of hydraulic failure the rear anti sink valve isolates the rear suspension system , so this fluid is not available to the rear brakes. An alternative emergency supply has to be arranged and this is provided by an additional accumulator. Logically this would be called the rear brake accumulator, but because it is associated with the anti sink system Citroen in their wisdom call it the anti sink sphere!
The emergency supply for the front brakes is of course supplied by the main accumulator.
splat
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Post by splat »

Thank you. That makes sense.
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