Xantia bouncy front suspension

[CitroJim]

Nope, you'll just carry on doing Tigger impressions Romie

You need to get it sorted sooner rather than later as it's a bit dangerous as it will upset the handling of the car and in an emergency it might not be good...

[romie]

You'd not really notice it that much on a different each side way Romie as the two sides are hydraulically interconnected. You'd just note an overall deterioration...

I just managed to crack off the two front spheres with one of these metal oil filter straps! Bit of luck!

Was just thinking about what CitroJim mentioned regarding the two front spheres being hydraulically interconnected.
There isn't another sphere in the front suspension system (other than front left/right spheres), that might cause this lack of dampening and so bouncyness is there?
Could the accumulator sphere also cause these symptoms?

Please excuse my lack of knowledge about this subject, could someone briefly say what does the accumulator sphere does? Accumulate excess hydraulic fluid I suppose? Isn't that what the reservoir is for? :/ hmm.

Cheers, romie (hydropneumatic learner!)

[Hell Razor5543]

From what I have read, the primary reason for the accumulator sphere (and the anti-sink sphere) is to hold enough pressure for the brakes to work should you lose the pump. A secondary reason is that it dampens out the pressure spikes from the pump, as these could cause damage if not managed properly. When the car is in the level, and at normal height, there should be a ticking sound every so often (with the engine running). How often does this happen on your car?

[romie]

From what I have read, the primary reason for the accumulator sphere (and the anti-sink sphere) is to hold enough pressure for the brakes to work should you lose the pump. A secondary reason is that it dampens out the pressure spikes from the pump, as these could cause damage if not managed properly. When the car is in the level, and at normal height, there should be a ticking sound every so often (with the engine running). How often does this happen on your car?

Good morning Hell Razor! How many coffee's have you had already today! (I'm on fourth).

Many thanks for your input! I did note your last point on this, and it's around every 15 seconds.

Hmm, how does this tick period relate to the accumulators functioning? I take it the accumulator sphere works on the same bases as the other spheres but then on what you said about its operation, the rubber diaphragm is used to store this hydraulic fluid pressure energy and release it when needed. So the ticking is something trying to maintain pressure in the sphere, and it's time between each tick is based on how quickly this pressure is 'escaping' from the sphere? :/

The accumulator sphere wouldn't have any impact on this lack of dampening though, no?

If the accumulator sphere is not functioning correctly then what parts could this cause damage/excess wear to?
HP, other spheres and seals between everything on the circuit?

Cheers, romie

[CitroJim]

The anti-sink sphere is misnamed and is called that because it was necessary to add it to the anti-sink system to act as an auxiliary rear brake accumulator to provide a source of pressure to the rear brakes in the event of the rear anti-sink valve being closed and thus denying the normal source of rear brake pressure.

The sphere has no effect on sinking or on damping! Likewise, neither does the main accumulator. James, an excellent description of the purpose of same

The ticking is the sound of the hydraulic pressure regulator cutting in and out like a thermostat to regulate the hydraulic pressure at 170 bar. It should make a tick no more frequently than at 30s intervals. Any less than 30s suggests that the accumulator sphere is weak and possibly flat. You van think of the accumulator as being a bit like a battery and flat batteries, like flat accumulators, will hold no charge.

A flat accumulator can cause damage through the pressure spikes mentioned by James going undamped. This has been known to cause pump and regulator damage.

By far the most dangerous aspect of a flat accumulator though is the immediate loss of braking should the pump drive belt break. A good accumulator is good for may brake applications.

A quick test of accumulator health is to switch off and them immediately sit in the tailgate. the suspension will sink and then 15 to 20s later the rear should rise to correct the height using stored pressure in the accumulator. Likewise when you get off and the rear rises there should be enough lest in the accumulator to make the downward correction too.

[romie]

Ah, fantastic. Thanks very much James and Jim! I'll go do some tests.. the brakes have always taken 45 seconds or so after the car has started to work first thing in the morning, maybe this shows no or little build up and storage of pressure in the system.

Is interesting when first starting up in the morning, reversing out forgetting I'll not have breaks for a few seconds. Having a long way out to the junction helped this problem :p

So the accumulator and anti sink sphere serve the same purpose.
I'd have one at front and one at rear?
Accumulator being at front and the rear one is called the 'anti-sink' sphere?

(Sorry, I'm just looking around for picture of all the spheres and their locations.)

[CitroJim]

Accumulator being at front and the rear one is called the 'anti-sink' sphere?

That's it Romie. They serve similar but not identical purposes. the main accumulator acts as a reserve of pressure (like a battery) for the whole hydraulic system (except steering) whereas the rear anti-sink is there only for the rear brakes.

[Xaccers]

Yes, when the pump stops running the pressure drops. This allows the nitrogen balloons in the spheres to expand and expel a bit of fluid which pushes the anti sink valves closed.
This isolates the rear brakes from the front accumulator which would leave the car with no rear brakes, so an accumulator at the rear is required to provide the pressure in an emergency.

[Hell Razor5543]

Based on the interval you have mentioned (as well as what I have read on the forum) I would suggest replacing both the accumulator and anti-sink spheres (Based on what somebody else on the forum wrote; I wish I could remember who it was), as they both basically serve the same purpose. However, replacing them probably won't resolve the bouncy suspension, but it will protect the system from the spikes the pump produces.

EDIT Xac mentioned replacing both spheres as there is no way to test the anti-sink sphere whilst fitted to the car, as mentioned in this post;

http://www.frenchcarforum.co.uk/forum/v ... ead#unread" onclick="window.open(this.href);return false;

[romie]

Great! Cheers guys!!

Thanks so much for your time answering my hydro-newbie questions

romie

[Hell Razor5543]

The location of the 6 spheres is that there is one per strut, the accumulator sphere (on the regulator down on the front of the engine), and the anti-sink sphere (roughly between the rear wheels, and hidden by the spare). Changing the spheres isn't difficult if you have the right tools (Xac has, in his signature, a link to the DIY sphere removal tool), and time and care.

[CitroJim]

Xac's sphere tool works very well and is cheaply and easily made...

I think I've already posted it but here's a link to everything you could possibly ever need to know about changing spheres Romie..

[romie]

Heya, following on from the leak issue, think the leak is under this black thing.

Will prob need a new gasket, any ideas on name and part numbers? :/



Cheers romie

[romie]

Damn, this looks like it.

Unfortunately not a serviceable part?
No Citroen part numbers

Is that the front accumulator in that diagram?

If the gaskets gone, I spose I'll have to cut one myself ~ sigh.

[romie]

I've just been to Euro Car Parts. They seem to be a bit confused regarding the spheres.

Is £31.80 an ok price for one of these?
So £63.6 for both? (Front Left and Front Right spheres)
Has anyone bought these from ECP and so know if you get the o rings with them?

Many thanks, romie