sphere shelf life

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Post by BX Bandit » Thu Nov 09, 2006 7:14 pm

RobC wrote:thanks for the tip! the ones i'm thinking of are genuine cit ones.

further to this, anyone heard of "IFHS" as a sphere manufacturer? if so any experiences good or bad?

:)
IFHS are in Belgium (I think) and as far as I know make new spheres rather than recon ones 9I suppose they may do both?)

I have been in contact with them regarding comfort spheres and who supplies them. AEP in Glasgow are a listed supplier and do not stock comfort spheres but supply to order. Additionally, I was informed that due to low volume requirements, comfort spheres are made to order rather than 'off the shelf' - meaning you get a 'fresh' set of spheres. I only found this out on Tuesday so I'll put up a new post with all the info I have. I expect tho' that standard IFHS spheres are 'off the shelf' and so may be hanging around for a while before purchase.
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Spheres.

Post by Geoffrey Gould » Thu Nov 09, 2006 8:40 pm

Just my two pennuth, I have found that Amtex quality has been questional to say the least 14/15 months seem to be about it. I have had some with deformed threads as well. Dates seen to be about 20/24 months old before you get them.
Having said that the local indy does not seem to have much trouble. Next time it will be original ones if they are still available.
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Post by docchevron » Fri Nov 10, 2006 2:09 am

ellevie wrote:Here's an interesting theory from the FrenchCarForum,
noz on the FCF wrote:When the sphere is on the shelf the diaphragm inside is completely pressed flat against the inside surface of the steel sphere. The diaphagm only occupies the lower half of the sphere, the top have being bare steel. The pressurised gas is pushing against all of the surfaces inside the sphere equally. The bottom part of the diaphragm has a hard plastic disc attached just where it passes over the orifice in the threaded part of the neck. The diaphragms are made of nitrile rubber compounds. At a molecular level the gas molecules will eventually pass through the diaphragm material just like a ballon which deflates after a while. However, this would only be the case if there was air on the other side of the diaphragm. When the sphere is on the shelf and the diaphragm is pressed against the inside steel surface then the migration of molecules is halted at the steel/rubber interface. Whilst it is not impossible for the gas molecules to pass through the steel this would take 10 orders of magnitude longer than through the rubber (due to the relative permeability of both materials). In which case the gas molecules may migrate through the rubber but they can't get any further than the steel surface. The only part of the diaphragm with contact to the outside air is the part above the orifice. At this point the diaphragm is thicker and capped with a hard plastic disc.

The only other part of the sphere which has the potential to leak is at the filler plug. Beneath the plug top there's a groove containing an o-ring. Its the o-ring which does the sealing.

When the sphere is in use the outside of the diaphragm is now no longer pressed against the inside steel surface of the sphere. The interface is now between the rubber and the LHM fluid. In this case the migrating molecules of gas passing through the diaphragm are able to escape into the fluid and be carried away back to the reservoir finally escaping to the atmosphere.

Overall my opinion is that the on-shelf sphere life is much greater than suggested above and previous writings on the same subject. The escape route for the gas is extremely limited. However, in use, the gas pressure will reduce as fast as the molecules can find their way though the molecular structure of the rubber.

I am not suggesting however that the pressure should not be checked before fitting the spheres to your vehicle. That simply constitutes good engineering practice.
Wow! all thats missing is Jennifer Aniston (or some other random bimbo) saying "HERE COMES THE SCIENCE BIT"!

Great theory but in practice it fails to explain why a "new" sphere from Amtex with a 2 year old date stamp is flatter than the torque curve of a zimmer frame????

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Post by ellevie » Fri Nov 10, 2006 11:10 am

And then there's the vexing question --- Why don't genuine Citroen spheres have date stamps ?

A while ago, I saw some "new" rear spheres going cheaply at EuroCarParts for about £13, so I ordered in a pair of them. They turned out to be genuine Citroen spheres with p/n 95564974 with a code 0-242-P stamped on them. Someone on the FCF says that this code can be interpreted as "year-day number" . So if this is true these spheres were made on day-242 year 2000. The single digit for the year could mean it was 1990. If the year digit is 5 then it could be 2005/1995/1985. Whatever it is, I would imagine that ECP were selling them cheaply because they were old stock. But just how old are they ?
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Post by Way2go » Fri Nov 10, 2006 2:28 pm

ellevie wrote:And then there's the vexing question --- Why don't genuine Citroen spheres have date stamps ?
Seems unreasonable not to on an item that is known to deteriorate on the shelf! Presumably though it is deliberate so an older item can't be quickly identified & then the seller rather than get into a regular debate with any buyer is only liable to replace (back-to-back with Citroen) any spheres that get fitted & found at this point to be duff. :evil:
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Post by ellevie » Fri Nov 10, 2006 2:53 pm

I think you're right. It seems really shortsighted of Citroen to have only used a single date for the year. For all I know , those spheres could have been manufactured in 1990 !
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Post by ellevie » Fri Nov 10, 2006 3:32 pm

jeremy wrote:Presumably this means that spheres don't last as long on a car with anti-sink as they do on one without - as they will be in the same state as when on the shelf whenever the suspension is lowered.
I suppose if noz's theory holds up, then it would make sense to always lower the car when not in use, especially if you don't use it very much. Trouble is, there's a small hump in my drive which catches the exhaust with much screeching if I forget to raise the suspension.
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Post by thanuttiscotsman » Fri Nov 10, 2006 4:30 pm

hi there,
when i got my 16v it had after market sphere's on that were fitted by previous owner 5 years before just prior to the vehicle being taken off the road. now they were hard as hell didnt move! but i also had a bx 1.4 that had been off the road for 1.5 years and 6 months before it went off the road i had put all round new genuine citro ones on. so after being advised that if i wanted a softer than normal 16v ride that 1.4 spheres would be perfect. so it took the spheres off the 1.4 knowing they were at least 2 years old (i.e thats when i bought them) and i put them on the 16v. now then the 16v suspension worked perfectly and was lovely and soft. strange thing is i put the at least 5 years old after market spheres on the 1.4 and the suspension worked perfectly and was almost as soft as the 16v. i know this sounds strange but its totally true.!!

rossco
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Post by ellevie » Fri Nov 10, 2006 7:56 pm

Hi Rossco,

It's a pity the front and rear spheres don't have the same damping apertures. If they did, it should be possible to only ever buy new front spheres and when the front nominal 55 bar spheres have fallen to 40 bar, stick'em on the back , and put new ones on the front. Of course you would need to be able to measure them exactly. I know the 16v is diffferent.

David
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Post by Way2go » Sat Nov 11, 2006 2:33 am

ellevie wrote:Trouble is, there's a small hump in my drive which catches the exhaust with much screeching if I forget to raise the suspension.
My drive has an even fall but when the pavement was re-tarmacced they put a small hump in that. So if I drive off too quick after starting the car then the exhaust clamp cuts grooves in the pavement at this point. :roll:
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