Suspension Problem - Peugeot 405 GRx4

"Peter Sheppard" skrev i melding news:djk3d.31541$ snipped-for-privacy@fe1.news.blueyonder.co.uk...

Hi Peter! (Sorry for my bad English)

I believe your problem is the accumulator. This should be a green "metallball" mounted under the back of your car. This is a part that is very easy to replace. It's like changing a normal light bulb. But it may be hard to get it loose in some cases. Now your car is very soft in the back. That's because the green ball is usually filled whith some sort of gas and is held in place by a membrane. When the membrane leaks the gas flows out to the hydraulic fluid and the car gets soft. After a while the gas will leak out to free air and the car will become very hard instead as there is nothing to compress.

Those green metallballs are also used in Citroens with hydropneumatic suspension.

Hope this will help!

Cheers Thomas.

case it looks pretty well plumbed into the hydraulic system. Do I assume I need to remove all the pipes and electrical connections to replace the "sphere"?

(I assumed from other posts that it just screwed in somewhere, but there is no sign of it on this car). Have a look at:

I reckon that this is the accumulator. So, do I have to remove all the connections to do the change? How much fluid will I lose?

Cheers

Peter

Hi!

That's the one yes! You don't need to remove anything but the "sphere". Just screw it out as it has threads(?) just like a light bulb. I changed my once on my old car (Mi16x4). It was really hard stuck, so I had to use a very big tool (tongs?). Just screw the same way as a light bulb.

You will not loose much fluid. I didn't. I think I lowered the car to minimum level before I started so there would be no preassure in the system.

If you don't know how to do it I will explain it for you: On the drivers side of the car in the boot (trunk) you will find a switch knob and a plug. The knob is to rise the suspension to the highest level. When you press it again it will wait a few seconds and go back to normal. The plug has to connections. Just take a screwdriver or somethind metal and shortcircuit these two connections. The car will sink down to minimum.

I hope this helped you. It is a very quick way of changing the "springs" on a car! :) (If it is not very stuck)

Cheers.

Thomas.

In Citroen parlance, they are spheres, and unscrew like oil filters - if you do it yourself you will probably need a strap or chain wrench like you use on a oil filter.

Have a chat with a back-street citroen specialist - they'll tell you 'how to do it' for sure.

Adam H

Hi,

All info in these posts is OK - strap wrench, release pressure beforehand etc, just like a hydropneumatic Citroen. I'd like to add:

- the release torque on the sphere will be around 40 lbs-ft-f - not very tight, but enough to call for a 1' lever for comfort;

- Citroen spheres are gas springs, filled with nitrogen at around 70-75 bar pressure. They lose 5-7 bar per year due to 'porosity' effects (molecular interstitial losses across the membrane), and need to be recharged every 4 years or so in order to keep the system they're fitted to in proper working order. If they lose sufficient pressure (due to neglect), the internal diaphragm gets punctured and the sphere is then a write-off (and would have to be replaced rather than refilled);

- you should check the level of the (presumably green LHM) suspension fluid before you start work on the sphere: because if the sphere's diaphragm is punctured, a certain amount of fluid will have migrated into the space previously occupied by the inert gas filler and will be lost when you unscrew the sphere from the axle housing;

- if there are other spheres on the axle (I don't know the GRx4, but there may be) bear in mind that they'll be in the same state as the accumulator sphere and will also need to be replaced;

- after seeing your website photos, I'd suggest most strongly that you consider replacing the hydraulic pipes as well as the sphere, as soon as you can, using cupro-nickel or Kunifer piping. I've found that this material works very well on Citroen suspension repairs because it's malleable and corrosion-resistant;

- if your brake pipes are in a similar state to the hydraulic pipes, I'd get those changed at the same time (using the same material - cupro-nickel). I realise that the cost of doing this work might actually be uneconomic, considering the age of the car - but it might be a lot cheaper than a sudden and unexpected MOT failure. If you feel inclined to keep your costs down by trying to do the work yourself, I can say that the only specialised tools you'll require will be a Sykes-Pickavant Flaring tool (or similar), with a supplementary die set that's been made especially for flaring the smaller-bore Citroen hydraulic piping (see below) - and a decent bench vice to hold it steady;

- if you need to buy replacement spheres, cupro-nickel piping (and the special pipe-flaring die set), and replacement hydraulic unions and rubber seals, one company that would probably help you is

I've had good dealings with them on alloccasions in the past, and would deal with them again anytime;

- the hydraulic suspension system on hydro Citroens is self-bleeding: you simply exercise it a few times to flush any trapped air back into the fluid reservoir (where it can escape), and that's it. However, the rear brake hydraulic circuit is usually supplied from the rear suspension hydraulic circuit (via the brake-pedal demand-valve), in order to make sure that rear brake power is regulated in direct proportion to rear-axle load. As a result, air (or gas) introduced to the suspension circuit can find its way into the rear brakes, and defeat how they should work - so it's necessary to bleed those items separately in order to make sure that all air has been eliminated. If *your* rear axle system is set up like this, you need to bear this in mind as well. Personally, I'd get the manual and see what's in store before making any decisions.

Good luck.

Regards,

Philip Andrews