arrrrghhhh xantia height corrector

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Mandrake
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Post by Mandrake »

erez wrote:on the box and on the spheres themselves it's written xantia
but i need to ask you this,
what is the preesure recommended for the rear spheres and for the front spheres, xantia 2.0i automatic.

right now i have 40 at the back and 50 at the front.
the back is a BX spheres.
Well,

You havn't told us everything we need to know about your car. Is it Hydractive 2, or not ?

Is it a hatchback or an estate ?

What year ?

Regards,
Simon
Simon

1997 Xantia S1 3.0 V6 Auto Exclusive in Silex Grey
2016 Nissan Leaf Tekna 30kWh in White

2011 Peugeot Ion Full Electric in Silver
1977 G Special 1129cc LHD
1978 CX 2400
1997 Xantia S1 2.0i Auto VSX
1998 Xantia S2 3.0 V6 Auto Exclusive
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Mandrake
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Post by Mandrake »

erez wrote:ok, understood.
but, it's not hard as "flat sphere hard" it's just not comfortable like the original ones, beside, my rear 40 spheres is very soft and very comfotable, although it's suppose to be 30.
Are you aware that a higher pressure causes a *softer* ride, not a harder ride ?

If the pressure is too high there can be side effects though, such as the diaphram bottoming out on the sphere base under light load conditions...(not to mention poor handling, and excessive squat under acceleration)

Regards,
Simon
Simon

1997 Xantia S1 3.0 V6 Auto Exclusive in Silex Grey
2016 Nissan Leaf Tekna 30kWh in White

2011 Peugeot Ion Full Electric in Silver
1977 G Special 1129cc LHD
1978 CX 2400
1997 Xantia S1 2.0i Auto VSX
1998 Xantia S2 3.0 V6 Auto Exclusive
erez
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Post by erez »

ok, the car is 2.0 8V 1997 without hydractive, hatchback

HOW HIGHER PRESSURE CAUSES SOFTER RIDE?
(i'm shocked)

b.t.w.
there is no xantia estate in israel....
this is my signature....
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Mandrake
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Post by Mandrake »

erez wrote:ok, the car is 2.0 8V 1997 without hydractive, hatchback
Ok in that case the rear spheres should be 30 bars.
HOW HIGHER PRESSURE CAUSES SOFTER RIDE?
(i'm shocked)
Well, without launching into a whole lot of maths, here is the simple explanation.

The quoted gas pressure of a sphere is its "pre-charge" pressure, which is the pressure when the sphere is not used, for example not fitted to the car.

When the hydraulic system pressurizes to lift the car the hydraulic pressure will rise to that necessary to lift the weight of the car, and in doing so it will compress the pocket of gas trapped by the sphere diaphram to the same "operating" pressure as the oil.

This means the gas pressure under actual operation is the same regardless of how much gas is in the sphere, it is determined only by load weight. However the compressed *volume* of gas in the sphere will depend on the pre-charge pressure.

High pre-charge pressure means not much compression of the gas required = larger volume, low pre-charge pressure means a lot of compression of the gas required = smaller volume.

Springing constant is defined as change in force over change in length. On a hydraulic system this translates to change in pressure for a given cubic displacement of oil.

A large gas volume means that a given cc displacement of oil causes a small percentage change in gas volume = small pressure change = soft springing constant.

A small gas volume means that a given cc displacement of oil causes a large percentage change in gas volume = large pressure change = stiff springing constant.

Ok maybe not such a simple explanation but I don't know how to describe it any more simply :)

Anyway, you only have to look at the fact that when spheres age and leak gas pressure (pre-charge pressure is dropping with age) the suspension gets stiffer, not softer...

Regards,
Simon
Simon

1997 Xantia S1 3.0 V6 Auto Exclusive in Silex Grey
2016 Nissan Leaf Tekna 30kWh in White

2011 Peugeot Ion Full Electric in Silver
1977 G Special 1129cc LHD
1978 CX 2400
1997 Xantia S1 2.0i Auto VSX
1998 Xantia S2 3.0 V6 Auto Exclusive
erez
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Post by erez »

does spheres have "shelf life"?
the spheres on the front were made in 2003.
is that counts as old?
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mezuk04
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Post by mezuk04 »

From posts on here it would appear they do have a shelf life, from the moment there made there wasting away (i think :shock:)...so if there 2 years old then i would be a little worried personally but thats only from what ive read on here...not personal experience :oops:
Volkswagen Golf 59' 1.6TD S :(
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Mandrake
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Post by Mandrake »

Yes,

They do have a shelf life, however it depends on the type of sphere, the ambient temperature, and also there seems to be a large random element to it.

The multilayer diaphram spheres used on the front suspension of some Xantia's (with the three dimples around the filler cap) last a very long time - even in use they can last as much as 5 years before any significant pressure loss and 10 years before needing replacing, so 2 years on the shelf for a multilayer sphere is nothing to be concerned about.

(I recently got a second hand pair that were 4 years old from a car that was written off when nearly new, and they were EXACTLY on pressure and had never been regassed)

On the other hand the normal single layer diaphram spheres don't last nearly as long, and with those I would be a little bit more concerned about them sitting on the shelf for 2 years - there will most likely be some pressure loss, but whether it is a significant amount or not is hard to say.

IMHO I wouldn't accept a sphere that had been sitting on a shelf for any more than 2 years as being "new" unless they were willing to pressure test it.

Regards,
Simon
Simon

1997 Xantia S1 3.0 V6 Auto Exclusive in Silex Grey
2016 Nissan Leaf Tekna 30kWh in White

2011 Peugeot Ion Full Electric in Silver
1977 G Special 1129cc LHD
1978 CX 2400
1997 Xantia S1 2.0i Auto VSX
1998 Xantia S2 3.0 V6 Auto Exclusive
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