Rear Suspension problems? Not Spheres!!!

Machra · Post by **Machra** » 31 Dec 2002, 11:42

1.9TD 1997
Over the past few months I have felt the rear suspension getting harder.
I have replaced all spheres, LHM change, and this week I replaced both rear
wishbone arm bearings. All to no avail.
Does anyone have any ideas as I seem to have run out.
The car sits 'naturally' so I don't think it is a ride hight problem. It
raises and lowers when the hight lever is moved.
If you push on the rear when the car is ticking over it feels soft but when
on the road you can feel every bump. One of the worst times is when you are
coming up to a local roundabout with those yellow stripes across the road
the car vibrates that badly that the hatchback lid vibrates.

alexx · Post by **alexx** » 31 Dec 2002, 12:20

Hm. For the start, check if the rear of the car is on the correct height anyway. It's 5 mm below the middle point between maximum and minimum height, with tolerance +/- 8 mm. Check if the correct height is maintained after the short journey also.
Since the car feels soft when pushed by hand, the problem can't be in fitting hydractive spheres instead of non-hydractive, I think. I'll also exclude rear suspension cylinders from the list of suspected parts for the same reason.
Old LHM wouldn't affect damping. My father has at least 15 yr old LHM (!) in his GS and the ride is perfect.
Was the anti-sink sphere replaced, as it's also important?

allmond · Post by **allmond** » 31 Dec 2002, 14:13

Don't know if this will help or confuse!
My Xantia hydractive system sometimes goes into hard mode and won't come out. The only solution I have found so far is to stop, switch off the ignition and restart.
It might help eliminate something for you.
Jamie

alexx · Post by **alexx** » 31 Dec 2002, 14:59

Machra, if your car has hydractive suspension (VSX level of trim), then the problem is probably related to hydractive sistem. If only the rear suspension is hard, than it can be faulty rear suspension control block. If the front suspension is also hard, than it can be one of the sensors or HA computer. Or only a bad electric contact somewhere.

Post by **Jon** » 31 Dec 2002, 15:34

Hardness of the rear suspension on Xantias of all types (even after the spheres and arm bearings have been replaced) can be caused by a sticky or seizing rear height corrector. Its a good idea to clean and lubricate the linkages and then put the car from the high to the low suspension position several times and see if that improves matters.
Jon Wood
forum@andyspares.com

alexx · Post by **alexx** » 31 Dec 2002, 16:49

It's true, but only on indirect way - if the height happens to be incorrect because of sticky mechanism of the corrector. If the car is to low, suspension arms will occasionally hit bump stops and the ride will be bouncy. If the car is too high, suspension arms will be in touch with rebound stops, causing 'working pressure' in spheres/cylinders to be higher than needed (that's what otherwise happens when the height lever is in the highest position), so the ride will also be bouncy.
During the drive, height corrector(s) doesn't influence the ride AT ALL. As soon as the car stands up, slide valve in the corrector closes connection to HP supply, so the rear cylinders are totaly isolated from the rest of the installation (except rear brakes and anti-sink sphere, and rear HA sphere on VSX models ).
Edited by - alexx on 31 Dec 2002 11:57:39

Dave Burns · Post by **Dave Burns** » 31 Dec 2002, 22:50

Check the rear subframe mountings, set suspension on high and jack up the rear, both wheels of ground and suported on axle stands/wood under jack points on the sill so the subframe is not loaded, lever the wheels up and look for excessive movement of the subframe and possible knocking.
Dave

Machra · Post by **Machra** » 03 Jan 2003, 12:07

Thanks for the replies. The car is not Hydroactive. I replaced the anti sink sphere but the car does sink about 3 or 4 inches when stopped could it be something to do with teh antisink valve. Would this affect the ride?

alexx · Post by **alexx** » 09 Jan 2003, 19:27

If the car sinks while at rest and the anti-sink sphere is new, the reason can be leaky brake valve, leaky anti sink valve, sticky rear corrector mechanism, leaky rear cylinders and maybe something else.
Anti sink sphere affects the ride to some extent, because it's connected with rear spheres vie the anti sink valve. I don't think the anti sink valve itself can affect the ride - during the drive, it's always open, because it works on the difference between the pressure in accumulator and in front /rear suspension.

jmd · Post by **jmd** » 09 Jan 2003, 23:51

I am very inclined to go along with Dave,Check your subframe mounts as Dave has suggested