non hydractive spheres for hydractive xantia

This is the Forum for all your Citroen Technical Questions, Problems or Advice.

Moderator: RichardW

User avatar
Mandrake
Posts: 8615
Joined: 10 Apr 2005, 17:23
Location: North Lanarkshire, UK
My Cars:
x 664

Re: non hydractive spheres for hydractive Xantia

Post by Mandrake »

DickieG wrote: Bear in mind that these sphere's are standard specification for a non Hydractive Xantia using a 1.8 engine and as stated earlier in the thread using standard TD/2.0 sphere's with a 1.5 damper will apparently give a firmer ride than a non Hydractive Xantia so I can't help thinking that 1.65 damper hole sphere's will suit your purpose perfectly.
He's not using 1.8/1.9D Xantia spheres though, he's using CX turbo spheres, so while the pressure and centre bypass holes might be similar the threshold valves may not have the same calibration. (I don't know of any easy way to determine this other than empirically by evaluating the ride/handling...)

If the threshold valves are too soft and open too easily then no amount of adjustment of the centre bypass hole will give proper damping control and ride. When the combination of gas pressure, threshold valve strength and bypass hole is optimal the rebound isn't quite strong enough to open the threshold valve and the entire rebound flows through the bypass hole in the middle, so the bypass hole critically tunes the rebound characteristic. (Bumps on the other hand do open the threshold valves, allowing them to be absorbed well)

If the threshold valve is too weak the rebound will just open the valve and flow through that way meaning rebound will always be poorly controlled no matter the bypass hole. On the other hand if the threshold valve is too stiff the ride will tend to be fidgety (think Hydractive 2 in hard mode) unless the bypass hole is overly large, but then the damping would be poor.

Only if the valve has an opening threshold that matches the car (gas pressure, body weight, mechanical advantage of the hydraulic system etc) can you get good ride and damping at the same time.

At the end of the day we really don't know what if any difference there is in the threshold valve between a CX and Xantia sphere, which is why I generally don't advise mixing spheres from completely different models... :? You might get lucky but you probably won't. Tweaking the centre hole may or may not help. Since its easy to try its worth a shot though, especially somewhere where it's hard/expensive to obtain replacement spheres.
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
User avatar
DickieG
Monaco's youngest playboy
Posts: 4877
Joined: 25 Nov 2006, 09:15
Location: Buckinghamshire
My Cars:
x 38

Re: non hydractive spheres for hydractive Xantia

Post by DickieG »

Mandrake wrote:
DickieG wrote: Bear in mind that these sphere's are standard specification for a non Hydractive Xantia using a 1.8 engine and as stated earlier in the thread using standard TD/2.0 sphere's with a 1.5 damper will apparently give a firmer ride than a non Hydractive Xantia so I can't help thinking that 1.65 damper hole sphere's will suit your purpose perfectly.
He's not using 1.8/1.9D Xantia spheres though, he's using CX turbo spheres, so while the pressure and centre bypass holes might be similar the threshold valves may not have the same calibration. (I don't know of any easy way to determine this other than empirically by evaluating the ride/handling...)
The ones he suggested buying and I'm describing are Xantia sphere's not CX ones,,,,,,
13 Ram 1500 Hemi
14 BMW 535D Tourer
19 BMW i3s
06 C3 Desire 1.4
72 DS 21 EFi Pallas BVH
aneesh84
Posts: 366
Joined: 31 Jul 2011, 22:29
Location: Lisbon, Portugal
My Cars:
x 28

Re: non hydractive spheres for hydractive Xantia

Post by aneesh84 »

DickieG wrote:
Mandrake wrote:
DickieG wrote: Bear in mind that these sphere's are standard specification for a non Hydractive Xantia using a 1.8 engine and as stated earlier in the thread using standard TD/2.0 sphere's with a 1.5 damper will apparently give a firmer ride than a non Hydractive Xantia so I can't help thinking that 1.65 damper hole sphere's will suit your purpose perfectly.
He's not using 1.8/1.9D Xantia spheres though, he's using CX turbo spheres, so while the pressure and centre bypass holes might be similar the threshold valves may not have the same calibration. (I don't know of any easy way to determine this other than empirically by evaluating the ride/handling...)
The ones he suggested buying and I'm describing are Xantia sphere's not CX ones,,,,,,
Thank you for your helpful tips. Actually the big problem with using these current Cx spheres is that while driving on not too smooth roads there is a slight but frequent side to side rocking motion even when I am driving straight. It is very smooth but still seems to be giving me a headache. I will try this soldering tip! However in case it doesn't work I doubt I can return these, so will need to go for new ones....
Last edited by aneesh84 on 29 Mar 2012, 14:23, edited 1 time in total.
Xantia Estate 1999 2.0 HDI 110
C5 2005 2.0 HDI 138
Nissan Leaf 2018 40Kwh
aneesh84
Posts: 366
Joined: 31 Jul 2011, 22:29
Location: Lisbon, Portugal
My Cars:
x 28

Re: non hydractive spheres for hydractive Xantia

Post by aneesh84 »

Today i did the bounce test on my front and the rear .... while the rear settled within 1 oscillation, the front settled after 2 oscillations. So i guess the main problem is that the front is underdamped. I will try to do that solder trick to reduce the bore size.... hopefully that should do the trick!
Xantia Estate 1999 2.0 HDI 110
C5 2005 2.0 HDI 138
Nissan Leaf 2018 40Kwh
addo
Sara Watson's Stalker
Posts: 7098
Joined: 19 Aug 2008, 12:38
Location: NEW South Wales, Australia. I'll show you "Far, far away" ;-)
My Cars: Peugeot 605
Citroën Berlingo
Alfa 147
x 93

Post by addo »

It may not, either. :? Far more fluid passes between the damper discs, than through the bleed orifice.

I suspect CX front spheres are less damped than Xantia because the car's nose weighs far more - this inertia would change the requirements for damping.

A "bodgy" test otherwise, would be one of the old spheres on your left front, leaving the new one on the right. This will give you uneven damping, which should stop the left-right rocking quite as much. The wheel closest to the outside of the road needs most softness (compliance), as the surface is more irregular at the edges. Mechanics observe a relationship with this detail when they change the outside ball joints and bushes more frequently.
User avatar
DickieG
Monaco's youngest playboy
Posts: 4877
Joined: 25 Nov 2006, 09:15
Location: Buckinghamshire
My Cars:
x 38

Re:

Post by DickieG »

addo wrote:A "bodgy" test otherwise, would be one of the old spheres on your left front, leaving the new one on the right. This will give you uneven damping, which should stop the left-right rocking quite as much.
Now that is a proper bodge :lol: :lol:
13 Ram 1500 Hemi
14 BMW 535D Tourer
19 BMW i3s
06 C3 Desire 1.4
72 DS 21 EFi Pallas BVH
aneesh84
Posts: 366
Joined: 31 Jul 2011, 22:29
Location: Lisbon, Portugal
My Cars:
x 28

Re:

Post by aneesh84 »

addo wrote:It may not, either. :? Far more fluid passes between the damper discs, than through the bleed orifice.

I suspect CX front spheres are less damped than Xantia because the car's nose weighs far more - this inertia would change the requirements for damping.

A "bodgy" test otherwise, would be one of the old spheres on your left front, leaving the new one on the right. This will give you uneven damping, which should stop the left-right rocking quite as much. The wheel closest to the outside of the road needs most softness (compliance), as the surface is more irregular at the edges. Mechanics observe a relationship with this detail when they change the outside ball joints and bushes more frequently.
I didn't understand, this would be the test to determine if the threshold valves on my cx spheres are good enough for me to use it with a reduced orifice? or this could be a possible solution ?

Otherwise if someone has experience, and can confirm that the 70 bar 1.65 400 cc non-turbo non-hydractive xantia spheres can give acceptable results, then I will just go ahead and order them and just accept that my previous order was a waste of money and live with it!
Xantia Estate 1999 2.0 HDI 110
C5 2005 2.0 HDI 138
Nissan Leaf 2018 40Kwh
aneesh84
Posts: 366
Joined: 31 Jul 2011, 22:29
Location: Lisbon, Portugal
My Cars:
x 28

Re: non hydractive spheres for hydractive Xantia

Post by aneesh84 »

Mandrake wrote:
DickieG wrote: Bear in mind that these sphere's are standard specification for a non Hydractive Xantia using a 1.8 engine and as stated earlier in the thread using standard TD/2.0 sphere's with a 1.5 damper will apparently give a firmer ride than a non Hydractive Xantia so I can't help thinking that 1.65 damper hole sphere's will suit your purpose perfectly.
He's not using 1.8/1.9D Xantia spheres though, he's using CX turbo spheres, so while the pressure and centre bypass holes might be similar the threshold valves may not have the same calibration. (I don't know of any easy way to determine this other than empirically by evaluating the ride/handling...)

If the threshold valves are too soft and open too easily then no amount of adjustment of the centre bypass hole will give proper damping control and ride. When the combination of gas pressure, threshold valve strength and bypass hole is optimal the rebound isn't quite strong enough to open the threshold valve and the entire rebound flows through the bypass hole in the middle, so the bypass hole critically tunes the rebound characteristic. (Bumps on the other hand do open the threshold valves, allowing them to be absorbed well)

If the threshold valve is too weak the rebound will just open the valve and flow through that way meaning rebound will always be poorly controlled no matter the bypass hole. On the other hand if the threshold valve is too stiff the ride will tend to be fidgety (think Hydractive 2 in hard mode) unless the bypass hole is overly large, but then the damping would be poor.

Only if the valve has an opening threshold that matches the car (gas pressure, body weight, mechanical advantage of the hydraulic system etc) can you get good ride and damping at the same time.

At the end of the day we really don't know what if any difference there is in the threshold valve between a CX and Xantia sphere, which is why I generally don't advise mixing spheres from completely different models... :? You might get lucky but you probably won't. Tweaking the centre hole may or may not help. Since its easy to try its worth a shot though, especially somewhere where it's hard/expensive to obtain replacement spheres.
Hi Mandrake, I spent some time reading up on how a sphere actually works. I have now been reading all your posts in this thread, and now it all makes much more sense.I think the next step is to get the soldering done! Will keep u updated.
Xantia Estate 1999 2.0 HDI 110
C5 2005 2.0 HDI 138
Nissan Leaf 2018 40Kwh
Post Reply