Wrong Spheres in the wrong place...

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CitroJim
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Wrong Spheres in the wrong place...

Post by CitroJim »

What would be the effect of using a suspension sphere as an accumulator sphere in practice? I'm interested but don't want to try it out in practice! I'm wondering especially if it would have any significant effect on PR operation.
Am I correct in believing that suspension spheres have a damper built into them whilst the accumulator sphere does not and has a bigger orifice?
Conversely, would using an accumulator sphere in place of a suspension sphere make for a very bouncy ride, being devoid of a damping funtion?
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Post by j_roc »

Anders or Malcolm can prob answer this question, as im still on the learning curve with this suspension
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Post by AndersDK »

Basic theme - simple answers :
Suspension spheres have a damper valve built in. Works as a shocker. Calibrated for each axle and each model variant.
Accumulator spheres does not have the damper valve.
Supension spheres may be used as accumulator spheres - but the other way round is not only foolish - it's dangerous during drive.
But as a quick DIY testing (car at standstill) for any faultfinding it's perfectly allright.
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Post by CitroJim »

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

Anders or Malcolm can prob answer this question, as im still on the learning curve with this suspension
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Me too[:D]
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Post by citronut »

i think anders is probably right,all though i dont see the need for this type of experimenting,as when cits are set up corectly i think they dont need tinkering with regards malcolm
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Post by CitroJim »

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

i think anders is probably right,all though i dont see the need for this type of experimenting,as when cits are set up corectly i think they dont need tinkering with regards malcolm
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Agreed Malcolm 100%. I was just sitting here speculating and thinking up some hypothetical "what ifs". It's one way I learn....
Good to know its OK to do it for test purposes though. Thanks for that!
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Post by j_roc »

I said Anders or Malcolm would be able to answer this question. We would be lost if they dident answer so many of our questions - cheers guys.
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Post by fastandfurryous »

Surely if a suspension sphere is fitted as an accumulator sphere there is a risk of it not being able to supply enough fluid for the brakes. As I understand it, the reservoir of high pressure fluid that the accumulator provides needs to be available instantly, and with a damping orifice in it, this may prevent that.
As relevant as that theory may or may not be, does it have any bearing in reality?
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Post by AndersDK »

F&F :
There may certainly be a bearing in your thoughts. On the other hand the damper valve is exactly designed to open on larger pressure change amplitudes (i.e. suspension accelerations) - which may supply any needed shift in LHM volume under pressure.
The brakes do not need much volume to lock.
On a good system you have at least 25 brakes actions on the spare pressure from the accumulator sphere.
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Post by jeremy »

But then there's ABS! which is presumably heavily dependant on there being a reserve of pressure - particularily on 2 piston Xantia pumps.
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Post by Kowalski »

Have a look at the central bore on the suspension sphere you're substituting for an accumulator, and compare that to the bore of the pipework feeding the brakes etc. If the orifice on the suspension sphere is smaller than the pipework, its a restriction, if it is about the same or bigger it'll make no (or little) difference.
Its also worth baring in mind that an accumulator is an 80bar sphere, and the highest pressure suspension spheres you can commonly get now are the 55bar front spheres for the TDs etc, so it would be like having a slightly flat accumulator sphere.
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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 Kowalski</i>

Have a look at the central bore on the suspension sphere you're substituting for an accumulator, and compare that to the bore of the pipework feeding the brakes etc. If the orifice on the suspension sphere is smaller than the pipework, its a restriction, if it is about the same or bigger it'll make no (or little) difference.
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The "centre bore" is just a small bypass hole that is there to allow gentle suspension movements not strong enough to open the washer valves (such as rebound) to slowly complete. More forceful flows of oil that open the washer valves allow much greater volumes of oil to flow.
From memory there are four holes for EACH direction somewhere around 2 to 3mm in diameter (depending on the sphere) which is a large area compared to one bypass hole of say 1.5mm.
<blockquote id="quote"><font size="1" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote">
Its also worth baring in mind that an accumulator is an 80bar sphere, and the highest pressure suspension spheres you can commonly get now are the 55bar front spheres for the TDs etc, so it would be like having a slightly flat accumulator sphere.
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Quite true. Unless it was a 75 bar sphere from the front of a CX [:D]
All in all, a bad idea except in an emergency.
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Post by dnsey »

I've never tried it, but it can't be too hard a job to remove the damper, as shown in a link from the recent regassing thread.
You'd still have insufficient gas pressure though.
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Post by AndersDK »

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

I've never tried it, but it can't be too hard a job to remove the damper, as shown in a link from the recent regassing thread.
You'd still have insufficient gas pressure though.
<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">I believe it's an early sphere type shown in the ref.
Recent spheres you can not remove the damper valve.
Is that a missprint Kowalski - as the standard acc spheres are 60-62 bar ?
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Post by Kowalski »

Not a typo or a misprint, just me being wrong.
According to the GSF sphere application table, the Xantia accumulators are 62 / 62.5 bar.
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