Citroen GS - Front suspension puzzler!

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chrisn
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Citroen GS - Front suspension puzzler!

Post by chrisn » 31 Mar 2011, 03:12

After having recently sampled the delights of a friends totally original & unmolested GS, I conclude that the ride of my own example is way below par!

Symptoms: The 'floating' feeling of being isolated from the road is non existant, the suspension doesn't cope well with rippled road surfaces and sudden undulations. It seems as though the suspension checks itself far too suddenly, almost as though its hitting the bump stops too early.

Of course!, I thought, it must be knackered front spheres. So these were replaced with new ones intended for a 1.4 BX. AFAIK GS spheres are no longer available and these are the accepted substitute. This improved things marginally, and at rest its now possible to push the car down 6 - 8 inches and it returns to height, so I conclude the spheres are not the problem.

I cleaned the LHM filter and tank, drained the system and refilled with Total LHM. Made no noticeable difference. A friend suggested that the height corrector could be clogged, as when weight is put on the front of the car it is noticeably slow to return to height. I've just replaced this with a refurbed item courtesy of Pleiades. Oddly it still seems slow to return to height, maybe the linkages need setting up, but there is noticeable improvement to the ride.

But its still not right.

Before you ask I'm not unusually pedantic! Honest!

This GS is the first Hydraulically suspended Citroen I've owned, so my own knowledge of such things is basically nil. I am keen to learn though, so I thought I'd submit the problem to the collective wisdom of the forum to see if anyone has any ideas!

Thanks,

Chris

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myglaren
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Post by myglaren » 31 Mar 2011, 06:48

Has the accumulator sphere been changed?

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DickieG
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Post by DickieG » 31 Mar 2011, 07:07

Are the rear sphere's OK? Quite a lot of the floaty ride is achieved by the rear suspension so the rear sphere's are very important on achieving a smooth ride. Also don't assume that whilst BX sphere's are used as a substitute for GS ones that they will provide as smooth a ride, when I bought my DS it was fitted with CX sphere's which similarly uses them as a substitute however the ride was nothing like as smooth as it is now on the correct original/split DS sphere's.

To fully check compatibility compare the size of sphere damper holes on GS and BX sphere's or have a word with Martin at Plieades re sphere specification etc.

citronut
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Post by citronut » 31 Mar 2011, 08:20

as Richard says try/check your rear end,

but the rear spheres do require the complete suspension cylinder/unit and sphere to be removed from the sub frame for sphere replacement,

or even check your front upper arm bearings and lower arm fluid block bush's,

to check your acumalater/regulater sphere, run the engine till the car is up to normal ride hight, switch engine off now hold the rear of the car down as far as you can,

if the A/C spheres is ok the car will push its self up against you trying to hold it down,


regards malcolm

addo
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Post by addo » 31 Mar 2011, 08:23

Borrow the friends wheels/tyres and compare again...

citronut
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Post by citronut » 31 Mar 2011, 08:29

yep tahts the other one, check tyre presures,

regards malcolm

chrisn
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Post by chrisn » 31 Mar 2011, 21:18

Thanks everyone!

Thats plenty to keep me occupied this weekend!!!

andmcit
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Post by andmcit » 31 Mar 2011, 21:33

Bx 1.4 FRONTS check out the same sphere spec with vol/jet/pressure
but be very wary about the same trick for the Gs's rears. Be careful about
Bx 16/19 spheres as there are listed differences. For the rears the nearest
would be a higher [by 5bar] pressure rear off a Bx 16/19 Carb Saloon,
BX17D sal and BX19D sal.

If I were you, I'd have a chat with Mr Pleiades or try shopping abroad for
replacement spheres if no joy with any suppliers in the UK - the correct
sphere jet is crucial for the 'wallow' effect on a G.


All the sphere spec is here:

http://www.google.co.uk/url?sa=t&source ... lw&cad=rja

:D

Andrew

andmcit
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Post by andmcit » 31 Mar 2011, 21:38

A Xant 1.6/1.8 & 1.9D NON HYDRACTIVE SALOON has a 400 vol/40 bar/1.1 jet
which isn't a milion miles from the G's rear of 400 vol/35 bar/1.1 jet

There's a lot more Xant stuff out there for sure.

Andrew

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Spaces
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Post by Spaces » 01 Apr 2011, 00:09

I've driven chrisn's car too, it feels like a good steel suspension at the front. Ripples which are usually absorbed by a GS/A aren't, but larger amplitude extensions of the suspension show it working correctly. It's feels like a bit of stiction, but pushing down on the front doesn't reveal it, back to back with a 'good' car. Chrisn has depressurised the susp and moved it through it's full travel - he says it feels smooth with no tight points.

Rear spheres are good - the rear end moves as a GS's should, highlighting the wooden front. Constriction in a pipe or an arm bearing which becomes tight when asked to move fast and when under load I wonder? Acc. ok in the sense it is not requiring the pump to operate frequently. But it's a thing to do. The height corrector has been replaced and all linkages made good.

Odd one, the car simply lacks the floating on air feel at the front, not at the back. As if it's connecting with bump stops at an inch of travel - which it clearly isn't as larger displacements are ok, ride height correct etc.

Are there such things as 'bad' cylinders? I've never known one, but I guess they may exist???

citronut
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Post by citronut » 01 Apr 2011, 07:52

you would not actualy phisicly feel the hight corector movement via the hight lever in the car,

as the H/C only makes minute movement's in normal use,

also if the upper arm bush's are breaking up/down, this would cause drag on the movement of the suspension, as in the BX rear arm bush faliure syndrom,


i fitted G fronts on the rear many years ago, and if you just looked at the throtle the rear would hit the bump stops,

regards malcolm

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Spaces
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Post by Spaces » 07 Apr 2011, 18:16

Problem mostly sorted with accumulator sphere swap. Front end still noisy and feels worn, squeaking/worn bush noise on 'bounce test' from lhs. I had wondered what the effect of a wrongly/lob-sidedly pre-loaded anti-roll bar would be. Anyone any idea?

citronut
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Post by citronut » 07 Apr 2011, 18:46

the squeaking could be the upper suspension are bearing breaking up,

regards malcolm

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AndersDK
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Post by AndersDK » 14 Apr 2011, 19:00

citronut wrote:the squeaking could be the upper suspension are bearing breaking up,

regards malcolm
Agreed.

The front lower control arm is held by the usual rubber bushes.
But the front upper suspension arm is held by roller bearings.
Just like the CX and the very early BX front suspension arms.

The problem is indeed wellknown from the similar bearings in the rear arm pivot bearings in the family including GS, BX, CX, Xantia, XM, Visa, C15 & C5.