Rear of Xantia sinks when pushed down

Xaccers · Post by **Xaccers** » 23 Feb 2007, 16:32

OK I'm probably sounding like a right numpty here, but my last Xantia was 7 years ago (and was torched by some local oiks) so I can't remember what that was like, but are you saying that it's normal for the rear to sink then come back up slowly (30sec) when you do the bounce test?
I've been expecting it to react like the front, where pushing down then letting go gives an instance bounce back up.

Post by **ekaftan** » 23 Feb 2007, 19:41

Xac wrote:OK I'm probably sounding like a right numpty here, but my last Xantia was 7 years ago (and was torched by some local oiks) so I can't remember what that was like, but are you saying that it's normal for the rear to sink then come back up slowly (30sec) when you do the bounce test?
I've been expecting it to react like the front, where pushing down then letting go gives an instance bounce back up.

Normal is:

-push down and hold: height corrector brings it up in 30 secs or less
-push down and release: comes back up immediatly

In both cases, with good spheres, you should be able to make it to the bottom stops with your weight alone.

Xaccers · Post by **Xaccers** » 23 Feb 2007, 20:14

Ok so what's likely to cause push down release immediately: car stays down for over 10 secs then slowly comes back up?

Post by **ekaftan** » 23 Feb 2007, 20:33

Xac wrote:Ok so what's likely to cause push down release immediately: car stays down for over 10 secs then slowly comes back up?

I would say something is releasing all pressure when moved to the bottom stop. A bad rear heigh corrector?

That, or very stiff arm bearings...

Never seen that before...

Mandrake · Post by **Mandrake** » 24 Feb 2007, 05:31

Does the same thing happen if you "lift" the rear - does it sort of hang there and then move down again when the height corrector moves ?

Could well be REALLY stiff (eg knackered) bearings with lots of drag...

With new spheres the springing rate is so soft that half the suspension travel is equal to a very small change in weight (eg you can just press it down with one hand leaning on it) so its possible for a stuffed bearing to cause enough drag to "hold" that new height until the height corrector makes a correction and forces it to move...

If they're that bad I would expect the ride of the car would be pretty awful...

Regards,
Simon

Xaccers · Post by **Xaccers** » 24 Feb 2007, 14:35

How about if the rear spheres sold to me by CAS in Leighton Buzzard and assured were for my car turned out to be for Hydractive suspension which I don't have?

SS127's so probably re-gassed too.

Anyone got any advice on how to get a refund without a reciept?

Mandrake · Post by **Mandrake** » 24 Feb 2007, 20:32

It's possible they're Hydractive spheres when they shouldn't be....

The result at the rear would be that it would be quite slow to rise after pressing down - about a second or two. Easy way to tell - remove one of the spheres and measure the hole in the middle.

(Easiest way is to use a set of small precision drillbits and find the size by inserting them in the hole)

If its around 0.5-0.6mm then its a rear Hydractive sphere, if its around 1.0-1.2mm then its a standard sphere.

Regards,
Simon

Xaccers · Post by **Xaccers** » 27 Feb 2007, 15:58

Sent dad to get non-hydractive rear spheres for my estate from GSF today.
They told him that as I tend to carry quite a bit of gear in the boot of my car, the rear spheres from a non-hydractive hatchback would be better suited.
Is this the case?

Mandrake · Post by **Mandrake** » 27 Feb 2007, 19:06

Xac wrote:Sent dad to get non-hydractive rear spheres for my estate from GSF today.
They told him that as I tend to carry quite a bit of gear in the boot of my car, the rear spheres from a non-hydractive hatchback would be better suited.
Is this the case?

Nope.

Sounds like BS

Havn't heard that little piece of "advice" before...

For a 1.9TD hatchback you have 30 bar rear spheres, for an estate, 40 bars. The damping valves are also different, with a larger hole in the estate spheres.

The main reason for the difference is the rear suspension hydraulic rams are different diameters - 35mm (pre 1995) or 37mm for the hatchback, and 40mm for estates.

When the ram diameter is increased the sphere gas pressure must be increased to MAINTAIN the same level of ride quality. If you put a hatchback sphere on an estate the result will be a stiffer harsher ride.

The other problem with having the gas pressure too low is that when you heavily load the car, the suspension will become excessively stiff and suspension travel will become very limited. (The diaphram in the sphere is too close to the top)

Contrary to intuition, a sphere with higher gas pressure will actually carry heavy loads better. (It can carry a heavier load before suspension travel becomes limited by the diaphram getting too near the top)

One of the first things you notice as rear spheres age and lose their gas pressure is the rear suspension starts to become very limited in travel when heavily loaded.

Citroen know what they're doing when they specified the spheres - just get the correct spheres for the car and be done with it... and don't pay too much attention to the advice of the counter jockies

Regards,
Simon

Xaccers · Post by **Xaccers** » 27 Feb 2007, 20:34

Well that's annoying.
Oh well, looks like I'll be stuck with hydractive spheres on the rear until after I move house at the weekend.