Hydropnumatic suspension

[Tourist]

I heard that a good way to tell how well a BXs suspension has been looked after is to see how smoothly it rises and descends. Is this true and if it moves in "stages" can this be resolved by a change of LHM fluid or is there more to it than this.

[DavidRutherford]

I heard that a good way to tell how well a BXs suspension has been looked after is to see how smoothly it rises and descends. Is this true and if it moves in "stages" can this be resolved by a change of LHM fluid or is there more to it than this.

The suspension is way more complex than that. Search this site and you will find all the answers you are looking for.

[Tourist]

Tried searching but without spending hours looking through threads and posts I can't find the exact answer I'm looking for.

The back is always smooth, rising and lowering but the front seems to do it in stages and not all in one movement.

If someone can explain why this is happening I'd appreciate it. If there's a simple way of fixing it, or reducing it then please let me know.

Thanks.

[rob-81]

One possible cause is sticky front struts - a common fault on BX's. There is a link in the DIY section to an article describing how this can be sorted.

[Aerodynamica]

This is not necessarily a 'fault' - the BX and the (Xm,Xantia etc) all use MacPherson type struts that demand a ram piston that has quite a long movement compared with the old skool Citroens such as the DS, GSA/CX etc. It can mean that the lifting of the front might show up surges in pressure supplied to it more than the old Cits because the movement of the piston is the same as the movement of the body rising up whereas the old ones' pistons moved much less in relation and so the 'spikes' in pressure can be 'ironed out' by inertia.

My Dad's old '94 Xanti did this from new as have both my BXes including Cyril the current one, I have rebuilt the correctors, linkages changed the LHM, lubed the struts and remedied the slight creaking, fitted a brand new pump, new accumulator but the front end still goes up in steps! It is also an early BX with the roller bearings for the lower suspension arms.

I think the stepping action can also be caused by the slightly firmer damper valves in the spheres of post 1980s Cits as the pressure on both sides of the damper might be out of balance in cycles while the car is pumping up.

But try lubing the struts up anyway - dead easy: there's a little access port at the strut top behind the sphere to access - put the suspension on low and when it's fully down you'll be able to see the upper seal or the strut/outer piston and can be WD-40'd then a minute later spray greased.

Worked for me!

[cauchoiskev]

It is also an early BX with the roller bearings for the lower suspension arms.

Off subject, but do you notice a difference between the precision of the steering between this car and the rubber-mounted ones ?

[Aerodynamica]

Hmm, not sure really as my first BX was also a Mk1 '84 but my Xantia of course, did have rubber bushes. I found the Xantia to have pretty crisp handling overall.

Funnily, the CX has rubber lower arm bushes but roller bearings for the upper arms. Again, pretty crisp response.

I do believe that the roller bearing BX rides 'floatier' though as my mate Steve commented on the difference riding in my BX to his Mk2.