Hi Guys,
I have Xantia VSX, the rear of it's is soft as a marshmello, however the front is quite firm. Personally I like it's handling perfectly.
Problem: My grandmother is in great pain and can't ride in there car anymore. I've offered the Xantia to them to use to see if she can ride in it.
I want this bugger to be soft as possible. Handling is unimportant, the car will most likely not go over 50km/h.
I've tried some GS sphere's on the front (that are down to about 70% pressure). Front *much* softer, the rail tracks and sharp bumps all but gone (most importantly, it's a gittery ride, more the rough that is bad). The front rises with accelleration, drops with harsh braking. Turn in much worse, but surpringly the car still drives reasonably ok. Not dangerous at all.
Next, I'll grease it's front struts and possibly see if I can get some DS spheres to fit in the limited space at the front. Before they grab it I will let the low profile 205/50 section front tires down to about 28psi.
Can anyone else think of anything that may improve the ride quality a little ??
seeya,
Shane L.
PS: Bugger it I wish I had a DS registered and roadworthy (as opposed to "in many bits") [:(!] [V]
Xantia ride comfort --how to improve
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DoubleChevron
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Assuming that your Xantia has Hydroactive II, then I think you are attacking this from the wrong angle.
I think that you should be able to get the same comfort with less degradation of the handling by increasing the pressure of the centre sphere and enlarging the HA damping holes.
The other thing which I think would significantly smooth the ride is to fit a weaker (non-HA) anti-roll bar.
I think that you should be able to get the same comfort with less degradation of the handling by increasing the pressure of the centre sphere and enlarging the HA damping holes.
The other thing which I think would significantly smooth the ride is to fit a weaker (non-HA) anti-roll bar.
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Richard Gallagher
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I've put non Hydractive spheres on mine, they give a smoother ride at very little expense in the handling department because the Hydractive system switches as soon as any roll/pitch is dectected. At that point the car now has 'normal' non Hydractive suspension.
Having said the above I wouldn't use any softer sphere's because there is a limit in the travel of each strut, to go any softer will result in hitting the bump stops on larger pot holes.
I've now done this swap on the last four Hyractive Xantia's I've owned and personally I find it works a treat.
Having said the above I wouldn't use any softer sphere's because there is a limit in the travel of each strut, to go any softer will result in hitting the bump stops on larger pot holes.
I've now done this swap on the last four Hyractive Xantia's I've owned and personally I find it works a treat.
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DoubleChevron
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<blockquote id="quote"><font size="1" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by xantiav6</i>
Assuming that your Xantia has Hydroactive II, then I think you are attacking this from the wrong angle.
I think that you should be able to get the same comfort with less degradation of the handling by increasing the pressure of the centre sphere and enlarging the HA damping holes.
The other thing which I think would significantly smooth the ride is to fit a weaker (non-HA) anti-roll bar.
<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">
Thanks Guys,
This is only temporary so I will not be making major changes like anti-roll bars. The H/A sphere is basically an accumulaor, you can't really make it's dampening holes any bigger !!! Increaseing it's pressure may impact ride slightly, but your sphere valving on the main suspension spheres will have a *much* larger impact on ride comfort.
It's actually not bad with the GS sphere's on the front. I'd put it on par with the ride quality of the early CX (though I haven't tested it much yet). I do NOT want to touch my hydractive suspension spheres. Most certainly no-one is going near them with a drill (you see I'd have to order newies in from the UK if something happened to them --they have very special valving if you have ever seen one).
BTW: bugger it all I tested the pressure of the Xantias front spheres while they were off and they need regassing [:(!] [V]
seeya,
Shane L.
Assuming that your Xantia has Hydroactive II, then I think you are attacking this from the wrong angle.
I think that you should be able to get the same comfort with less degradation of the handling by increasing the pressure of the centre sphere and enlarging the HA damping holes.
The other thing which I think would significantly smooth the ride is to fit a weaker (non-HA) anti-roll bar.
<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">
Thanks Guys,
This is only temporary so I will not be making major changes like anti-roll bars. The H/A sphere is basically an accumulaor, you can't really make it's dampening holes any bigger !!! Increaseing it's pressure may impact ride slightly, but your sphere valving on the main suspension spheres will have a *much* larger impact on ride comfort.
It's actually not bad with the GS sphere's on the front. I'd put it on par with the ride quality of the early CX (though I haven't tested it much yet). I do NOT want to touch my hydractive suspension spheres. Most certainly no-one is going near them with a drill (you see I'd have to order newies in from the UK if something happened to them --they have very special valving if you have ever seen one).
BTW: bugger it all I tested the pressure of the Xantias front spheres while they were off and they need regassing [:(!] [V]
seeya,
Shane L.
Putting non HA spheres on a car with HA does not give the same handling as a non HA car.
On a non-HA car, if the suspension is moved from static equilibrium to fully compressed, all of the voume of oil moved from the cylinder goes into the sphere.
On a HA car, when the suspension is fully compressed on a bump, most of the oil moves into the centre sphere before the HA valve closes, leaving only a little oil to compress the corner sphere. If a standard sphere is fitted, it will take that much oil before the spring rate increases enough, making it more likely to bottom out than either a HA or non-HA car with correct spheres.
On a non-HA car, if the suspension is moved from static equilibrium to fully compressed, all of the voume of oil moved from the cylinder goes into the sphere.
On a HA car, when the suspension is fully compressed on a bump, most of the oil moves into the centre sphere before the HA valve closes, leaving only a little oil to compress the corner sphere. If a standard sphere is fitted, it will take that much oil before the spring rate increases enough, making it more likely to bottom out than either a HA or non-HA car with correct spheres.
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Richard Gallagher
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As far as handling is concerned, the HA valve is switched off not only electrically by way of numerous sensors BUT also a small ball bearing which floats around in the valve.
As soon as the car rolls, fluid moves towards the HA valve causing the ball bearing to move and block off the flow of fluid, therefore leaving the corner sphere to do all the work, as per a non HA car.
So unless the car is faced with a bump which runs at a right angle to the way the car is facing and both wheels hit it at the same time, there will be very little likelihood of the car bottoming out. Trust me on this, mine doesn't.
As soon as the car rolls, fluid moves towards the HA valve causing the ball bearing to move and block off the flow of fluid, therefore leaving the corner sphere to do all the work, as per a non HA car.
So unless the car is faced with a bump which runs at a right angle to the way the car is facing and both wheels hit it at the same time, there will be very little likelihood of the car bottoming out. Trust me on this, mine doesn't.
Well, I reckon you're both wrong. Sort of [:p]
xantiav6:
I have to disagree with the claim that "most of the oil" moves into the centre sphere when a bump is absorbed - that may be true if there were TWO centre spheres, so that each side had it's own, but there is only one centre sphere shared between both sides, which means that only half the compressibility of ths sphere is available for one side of the suspension to use.
(While the right strut being compressed would try to send oil towards the centre sphere, the flow from right to centre is partly counteracted by the flow from left to centre as well)
The gas pressure of the side spheres is 50 bars and the centre one is 70 bars, but effectively only half that is available to each side, so springing wise you have two struts sharing 3 spheres. Although I won't go into the calcualations it can be shown that more oil will be going into the side spheres during a bump than the centre sphere due to this sharing of the centre sphere.
It's also a bit misleading to say that a certain amount of oil is going into the centre sphere "before the valve closes" which kind of implies that the suspension detects a large bump and closes the valve, but in fact there is no sensor that measures bumps for the HA computer.
It's responding to steering wheel angle and velocity, braking, acceleration, speed and so on, but not to individual bumps or instantaneous suspension movement. It's responding to things that will cause roll (steering wheel angle vs speed etc) or pitching. (heavy braking) It doesn't actually measure the roll or pitching directly.
Richard:
The ball valve you're refering to doesn't have any role in switching from "soft" to "hard" mode in HA2, it's there simply to block the direct flow of oil from left to right which would occur with the very large pipes used to the sides on a HA2 car.
A non HA2 car has very skinny pipes on purpose to minimize this cross flow.
In "soft" mode, the ball valve does close during cross flow, but the oil is still able to flow from one side to the other via the two damper valves in series in the control block. (And also into and out of the centre sphere)
Because oil flowing in response to roll has to pass through TWO damper valves in series, there is more damping for roll movements than there is for up and down bump absorbtion in soft mode. (As up and down bumps only have to travel from each side through one damper valve each to the middle) This is good because it increases damping against roll without making overall ride damping too firm.
When the solenoid switches it to "hard" mode, now the damper valves are blocked off, and the ball valve will also block during roll, so that there is NO cross flow of oil from one side to the other during roll in hard mode....
Although I havn't tried it, in theory putting "normal" Non-HA2 spheres on a HA2 car side spheres should make the "hard" mode ride about the same as a non-HA2 car, but with a bit less roll (due to the ball valve blocking the cross flow) while in the "soft" mode it would be considerably softer than a standard non-HA2 car, including roll.
Regards,
Simon
xantiav6:
I have to disagree with the claim that "most of the oil" moves into the centre sphere when a bump is absorbed - that may be true if there were TWO centre spheres, so that each side had it's own, but there is only one centre sphere shared between both sides, which means that only half the compressibility of ths sphere is available for one side of the suspension to use.
(While the right strut being compressed would try to send oil towards the centre sphere, the flow from right to centre is partly counteracted by the flow from left to centre as well)
The gas pressure of the side spheres is 50 bars and the centre one is 70 bars, but effectively only half that is available to each side, so springing wise you have two struts sharing 3 spheres. Although I won't go into the calcualations it can be shown that more oil will be going into the side spheres during a bump than the centre sphere due to this sharing of the centre sphere.
It's also a bit misleading to say that a certain amount of oil is going into the centre sphere "before the valve closes" which kind of implies that the suspension detects a large bump and closes the valve, but in fact there is no sensor that measures bumps for the HA computer.
It's responding to steering wheel angle and velocity, braking, acceleration, speed and so on, but not to individual bumps or instantaneous suspension movement. It's responding to things that will cause roll (steering wheel angle vs speed etc) or pitching. (heavy braking) It doesn't actually measure the roll or pitching directly.
Richard:
The ball valve you're refering to doesn't have any role in switching from "soft" to "hard" mode in HA2, it's there simply to block the direct flow of oil from left to right which would occur with the very large pipes used to the sides on a HA2 car.
A non HA2 car has very skinny pipes on purpose to minimize this cross flow.
In "soft" mode, the ball valve does close during cross flow, but the oil is still able to flow from one side to the other via the two damper valves in series in the control block. (And also into and out of the centre sphere)
Because oil flowing in response to roll has to pass through TWO damper valves in series, there is more damping for roll movements than there is for up and down bump absorbtion in soft mode. (As up and down bumps only have to travel from each side through one damper valve each to the middle) This is good because it increases damping against roll without making overall ride damping too firm.
When the solenoid switches it to "hard" mode, now the damper valves are blocked off, and the ball valve will also block during roll, so that there is NO cross flow of oil from one side to the other during roll in hard mode....
Although I havn't tried it, in theory putting "normal" Non-HA2 spheres on a HA2 car side spheres should make the "hard" mode ride about the same as a non-HA2 car, but with a bit less roll (due to the ball valve blocking the cross flow) while in the "soft" mode it would be considerably softer than a standard non-HA2 car, including roll.
Regards,
Simon
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Peter.N.
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Simon - thanks for your exhaustive description of the HA suspension. I was considering putting non HA spheres on my Mk2 XM but they dont seem to be available, are there any with similar spec? I dont like this modern preocupation with hard suspension so that you can corner at 60 MPH, I don't drive like that, I like my comfort, I want a ride like the DS! I dont think that low profile tyres do anything for ride comfort either.
Hi Shane -
I'm pretty confident you can take the wellknown DS/ID (and some CX owners mod as well) modder route here - even considered the HA2 system onboard.
After all you would not consider such a DS/ID dangerous to drive at speeds - as you have the direct feedback from bodyroll.
I'm thinking of increasing the center bore - on a sphere calibrated for front usage on a Xantia.
I'm pretty confident you can take the wellknown DS/ID (and some CX owners mod as well) modder route here - even considered the HA2 system onboard.
After all you would not consider such a DS/ID dangerous to drive at speeds - as you have the direct feedback from bodyroll.
I'm thinking of increasing the center bore - on a sphere calibrated for front usage on a Xantia.
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Kowalski
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Did Porsche run the pressures higher too? More air would mean a more linear travel of the tyre surface, softer but the wheels would be more prone to damage by big bumps.
I have a colleague with a BMW on 18" rims and his tyre pressures are in the mid 40s i.e. quite high. If the pressures were lower I suppose he'd end up braking a wheel every time he hit a big pothole.
I suppose this is all related to the way sphere sizes and pressures affect the hardness of suspension.
I have a colleague with a BMW on 18" rims and his tyre pressures are in the mid 40s i.e. quite high. If the pressures were lower I suppose he'd end up braking a wheel every time he hit a big pothole.
I suppose this is all related to the way sphere sizes and pressures affect the hardness of suspension.
<font color="blue"><font size="2"><font face="Comic Sans MS">Hi Guys,
I have to get an accumulator, and 2 rear spheres for my 16v VSX Xant, Hydractive. I only want comfort, never use the hydractive switch ( costs money to go flying about ). As Richard suggests, do I get ordinary rear spheres or the hydractive ones. The fronts have been changed--how does one tell what has been fitted?.
This car will be for sale soon--going back to a common old LX TD--not so much to go wrong [8)] .
Thank you
Greg</font id="Comic Sans MS"></font id="size2"></font id="blue">
I have to get an accumulator, and 2 rear spheres for my 16v VSX Xant, Hydractive. I only want comfort, never use the hydractive switch ( costs money to go flying about ). As Richard suggests, do I get ordinary rear spheres or the hydractive ones. The fronts have been changed--how does one tell what has been fitted?.
This car will be for sale soon--going back to a common old LX TD--not so much to go wrong [8)] .
Thank you
Greg</font id="Comic Sans MS"></font id="size2"></font id="blue">
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DoubleChevron
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What is there to go wrong on the Hydractive Citroens ?? It's still only hydraulic valves & switches.... They rarely if ever cause problems.
Don't put normal spheres under it's bum, they are so soft with hydractive spheres I you can hit the bumpstops at the back quite regually. Most importantly ensure your rear hydractive sphere is ok. Do NOT ignore the hydractive sphere, it's this sphere that gives you additional ride comfort (it does have a great impact on rear harshness -- I know 'cos it was dead on mine).
seeya,
Shane L.
Don't put normal spheres under it's bum, they are so soft with hydractive spheres I you can hit the bumpstops at the back quite regually. Most importantly ensure your rear hydractive sphere is ok. Do NOT ignore the hydractive sphere, it's this sphere that gives you additional ride comfort (it does have a great impact on rear harshness -- I know 'cos it was dead on mine).
seeya,
Shane L.
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RichardW
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"I only want comfort, never use the hydractive switch "
This doesn't matter, since the switch only alters the point at which the car goes into hard mode. It will still go hard cornering / braking etc in'comfort', just needs a bit more provocation. You might as well leave it switched on to get the best handling.
This doesn't matter, since the switch only alters the point at which the car goes into hard mode. It will still go hard cornering / braking etc in'comfort', just needs a bit more provocation. You might as well leave it switched on to get the best handling.