Xantia TD VSX Harsh ride.

Paulee · Post by **Paulee** » 04 Jul 2005, 14:21

My 92 VSX TD Xantia feels harsh on the rear suspension and isn't riding small potholes like it used to ! It also has a tendancy to change ride height at the rear when stationary with the engine running and my foot on the brake pedal.Other than the usual sink problem overnight it seems fine in all other respects and rises in around 30 seconds and the front suspension seems spot on, where should I start looking ?
cheers...Paul

Mandrake · Post by **Mandrake** » 04 Jul 2005, 14:43

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by Paulee

My 92 VSX TD Xantia feels harsh on the rear suspension and isn't riding small potholes like it used to !
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92 ?? I thought the first Xantia's came out in 93 ? [:D]
Rear hydractive sphere has gone perhaps ? This would cause the rear to effectively be in "firm" mode all the time, even when the computer selects soft. How far does the rear suspension compress when you push on it compared to the front ? Try this with the engine idling to make sure the computer has the suspension in "soft" mode. The rear suspension should be a bit softer than the front. (Since there is less weight at the back)
Another possibility is faulty rear suspension arm bearings.
Faulty spheres will cause the suspension to just be very hard (or completely hard) while arm bearings would make the movement of the suspension feel like it has a lot of friction, and the wheels may also have negative camber.
Faulty arm bearings will cause it to be impossible to move the suspension a small amount, as a certain amount of force would be required for any movement to overcome the static friction. (Which could exacerbate rear height changes with braking mentioned below, as well as causing a harsh ride)
<blockquote id="quote">quote:<hr height="1" noshade id="quote">
It also has a tendancy to change ride height at the rear when stationary with the engine running and my foot on the brake pedal.
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Depending on how you drive, this can be normal behaviour, especially with an automatic.
Basically when you brake moderately hard the rear suspension will lift a bit, and if you're still braking hard when you come to a complete stop the rear brakes will hold the rear suspension up a bit.
After a few seconds the height corrector will try to lower the height, but the brakes can hold quite a bit of weight before they will let it go down, depending on how hard you're pressing the brakes.
The answer is to ease off on the brakes just as you come to a final stop to allow the height to normalize, although it's easier said than done on an automatic, since you're fighting the auto with the brakes unless you put it into neutral...
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Other than the usual sink problem overnight it seems fine in all other respects and rises in around 30 seconds and the front suspension seems spot on, where should I start looking ?
cheers...Paul
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If your car is an early model like a '93 it won't have the anti-sink valves of the later models, (introduced mid '94) so going down and taking 10-20 seconds to lift up is normal, although 30 sounds a bit excessive. An anti-sink model can typically stay up for 2 - 5 days easily.
Low gas pressure in the accumulator (in particular) and suspension spheres can cause it to take longer to pressurize than normal, so if all or some of the spheres are getting a bit low on gas thats one thing that could explain a long lift time.
Regards,
Simon

Paulee · Post by **Paulee** » 04 Jul 2005, 15:19

Sorry Mandrake the car is a June 93 manual model !!!!
I can understand the rear ride height changing when braking as you described.
When pushing the rear of the car down it is very smooth and soft and returns to the same height, I have also noticed how it firms up when filling with diesel,and I recently carried about 400kg in it no problem with the height constant.
As far as the computer goes it is not an Activa model but just has the sports/normal switch .
The 30 seconds it takes to rise is when left overnight ,in general use it takes a mere 5 seconds to rise during the day.
According to the service history it had an lhm change,accumulator and 2 rear spheres at 65,000 and a rear sphere at 72,000.I changed the LHM at 95,000 and it now has 98,000 showing.........
cheers Paul

Mandrake · Post by **Mandrake** » 04 Jul 2005, 16:58

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by Paulee

Sorry Mandrake the car is a June 93 manual model !!!!
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Thought it must be, unless there were some earlier models I wasn't aware of [:D]
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I can understand the rear ride height changing when braking as you described.
When pushing the rear of the car down it is very smooth and soft and returns to the same height,
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Ok, if the movement is soft and smooth, that should rule out rear suspension arm bearings. (I presume you also checked by eye the rear wheels didnt have any negative camber)
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I have also noticed how it firms up when filling with diesel,and I recently carried about 400kg in it no problem with the height constant.
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Yep, thats right. The suspension is designed to get progressively stiffer as you increase the load, this keeps the ride and handling/damping largely constant with load changes.
If you load it up with the 400kg, does the suspension still maintain a reasonable (but much stiffer) range of travel ? If the gas pressure is low when the rear is heavily loaded the suspension travel will be severely limited, although the height will always be normal. (You would notice a lot harder ride with the extra load while driving too, whereas the ride should stay about the same if the spheres are all good)
<blockquote id="quote">quote:<hr height="1" noshade id="quote">
As far as the computer goes it is not an Activa model but just has the sports/normal switch .
The 30 seconds it takes to rise is when left overnight ,in general use it takes a mere 5 seconds to rise during the day.
According to the service history it had an lhm change,accumulator and 2 rear spheres at 65,000 and a rear sphere at 72,000.I changed the LHM at 95,000 and it now has 98,000 showing.........
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One more test you could try is to run the car until height is normal, then switch off the engine, close all the doors, lock it, and leave the car alone for half an hour.
Initially the suspension will be in "soft" mode which requires a solenoid to be energized, and you may hear a faint buzzing noise from under the car. After about 10 minutes a battery saving mode kicks in and turns off the solenoids putting the suspension into "firm" mode.
Give it 30 mins just to make sure, but not long enough to allow the suspension to go down, then go over and immediately press down on the rear suspension without opening any doors or the tailgate - this time you're checking the firmness in firm mode instead of soft mode.
It should be somewhat firmer than before. If its totally solid and yet at normal ride height that would suggest that the rear corner spheres are faulty and you're only riding on the inner hydractive sphere, on the other hand if there is no change to before and it feels about the same, then the rear centre hydractive sphere is probably stuffed. (There is a small chance the solenoid is faulty too, but its not likely)
The most common reason for a harsh ride at the rear even though there is still plenty of soft (but slow moving and slow rebounding) travel when you push down by hand is failure of the hydractive sphere - because the corner spheres on a hydractive car have VERY firm damping compared to a standard model - achieved by a very small diameter damper hole.
Without that centre sphere working you would get a very heavily damped but fidgety ride that allows small road irregularities to be felt, (harshness) and yet it will pass over large bumps like judder bumps quite well. (Still plenty of travel for large bumps)
As I mentioned, a fault with the solenoid that switches between the two modes can cause the same symptoms, but is much less likely to be the actual cause, until the sphere has been eliminated.
In the firm mode you should notice when you press the suspension down its quite slow to rebound, with no overshoot, while soft mode should give a faster rebound.
If you then open a door and/or switch on the engine it will revert to the soft mode again. Might pay to try this test on the front as well to get an idea of the difference, assuming the front is working ok.
Regards,
Simon

Paulee · Post by **Paulee** » 02 Aug 2005, 16:56

Hi Simon sorry for the delay I have been run off my feet with my business.
The car behaves as it should in your descriptions in that it stays soft when switched off and locked and firms up after a while before sinking to the ground.By doing the tests you suggested I have now noticed the ride to be "thumpy" with minor potholes at the front and rear also the pump on tickover is coming in around every 25-30 seconds.....I thought 45 seconds was normal could these problems be linked ?
kind regards...Paul