C5 2009 excl. suspension - how to check?

[Paul-R]

I thought that the speed controlled height control (lowered at high speed, raised a little bit on slow bumpy roads) was also on the HA3. I don't have my early handbook to hand but memory thinks so.

Page 115 of the handbook talks about this but doesn't specify that it has to be certain type of suspension so I reckon it must be both HA3 and HA3+ that do this.

[vborovic]

[Mandrake]

The disappointing thing to me is that after the Xantia each generation of Hydractive got more sophisticated (especially the C6 and C5 X7) and they even returned to double wishbones instead of McPherson struts... but they kept tuning the suspension stiffer and more sporty with each model to keep up with the Joneses! So you end up with a system that is really clever and could potentially ride very well and handle very well with a lot of flexibility in between, but then you throw it all away by tuning it so firm so that it doesn't ride that much better than coil springs...

I think a soft wafty ride is simply "out of fashion" at the moment in the driving populace, hence Citroen's gradual tuning towards more and more sporty to keep up with (mostly) their German rivals, and now abandonment of Hydractive altogether, after the cost/benefit equation no longer makes sense. (Why have all the extra complexity and cost if the ride isn't that much softer) In essence, Citroen forgot the roots of Hydro-pneumatic which was always ride comfort.

[The Ace]

The disappointing thing to me is that....you end up with a system that is really clever and could potentially ride very well and handle very well with a lot of flexibility in between, but then you throw it all away by tuning it so firm so that it doesn't ride that much better than coil springs...In essence, Citroen forgot the roots of Hydro-pneumatic which was always ride comfort.

I have an almost opposite view on the subject. Since we are discussing this very issue on the greek forum, a fellow C5 owner mentioned that, at some point in time, for an unexplicable reason, his C5 got stuck in Sport mode and a 3/4 elevated height position for a couple of hours. He found this peculiar situation the best, handling-wise, period of his C5. Since we have already mentioned that HA1 was an "on/off" kind of suspension, and since HA3+ can do all sorts of manipulations due to its electronic-based control methods, it would be even better if there were some kind of "Sport+" button (or an extended press of the existing "Sport" button ?) that actually locks the HA3+ in the "stiff" settings, rules and thresholds. And I would also prefer it this "Sport+" mode was even stiffer, i.e. foregoing comfort for the sake of handling and performance.

So HA3+ would still have its "Normal"/comfort mode, it would still have the auto "Sport"/stiff mode, but it would also have the HA1's functionality of locking-on the Sport+ settings permanently, at least until shutting off the engine. If this reminds you of Alfa's DNA setup, or BMW's Dynamic setup, I confess, it is something that I would love to have in my C5

[GiveMeABreak]

The disappointing thing to me is that after the Xantia each generation of Hydractive got more sophisticated (especially the C6 and C5 X7) and they even returned to double wishbones instead of McPherson struts... but they kept tuning the suspension stiffer and more sporty with each model to keep up with the Joneses! So you end up with a system that is really clever and could potentially ride very well and handle very well with a lot of flexibility in between, but then you throw it all away by tuning it so firm so that it doesn't ride that much better than coil springs...

I think a soft wafty ride is simply "out of fashion" at the moment in the driving populace, hence Citroen's gradual tuning towards more and more sporty to keep up with (mostly) their German rivals, and now abandonment of Hydractive altogether, after the cost/benefit equation no longer makes sense. (Why have all the extra complexity and cost if the ride isn't that much softer) In essence, Citroen forgot the roots of Hydro-pneumatic which was always ride comfort.

I agree with every single part of what you have said Simon, you are spot on.
Nothing has compared to the GS or CXs I owned - even the XM, of which I had 3, never did it for me The XMs (without comfort spheres - and I'm guessing that's why those were introoduced!) - never had the supple ride of the GS or CX (I never owned a BX, but I'm sure they were fine too). I found the XMs too jerky and the the ride at low speed <30 could be bumpy, but moreso, I found that these could have 'good' days and 'bad' days - sometimes it would ride perfectly and other time it would jerk over the smallest pebble.

The electronics surely have to be the cause - without these the fluid and gas just react naturally - start intervening and adjusting the damping / springing and I just don't think the system can react quick enough - as let's face it by the time the car has decided this is a bumpy bit of road and we better adjust things - you're over it allready!

[jgra1]

I agree with all those 3 posts

[GiveMeABreak]

I have an almost opposite view on the subject. Since we are discussing this very issue on the greek forum, a fellow C5 owner mentioned that, at some point in time, for an unexplicable reason, his C5 got stuck in Sport mode and a 3/4 elevated height position for a couple of hours.

Sport mode doesn't elevate the car Ace - rough roads will do that and only under a certain speed, but not by 3/4 for sure. I think the person your referring to has a dodgy height corrector that's all.

[The Ace]

I know, he said that the "Track" stance during that period was obviously a malfunction, albeit a temporary one...nonetheless, he found the handling of his C5 during that period the best overall, even though that car actually had a higher stance than Normal. Imagine if it had the sport/highway stance

I mentioned that to point out that a "Sport+" mode that would work similar to HA1 would be something I would really like to have in my C5...

[jgra1]

I have changed the stance of mine for a week. Annoyingly the handling is still odd. Just (still) understeers and very unpleasant as a 'drivers car'

Was just experimenting with rear ride height a bit.. may change it back later today..

[white exec]

In a nutshell, Simon.

There's not much there (C5, C6) that interests me, or would tempt me to buy one, and plenty of technical reasons not to (don't disconnect the battery, don't jack it up without...). In the case of the C6, it was hardly there before it was gone, selling only in tiny numbers.

Even if Citroen have been told to stop development of hpn systems, it thankfully seems that others are not dissuaded...
http://www.caranddriver.com/features/th ... ed-feature
Just google 'McLaren hydraulic suspension' for lots more.

[Mandrake]

The Kinetic system is very interesting - it was used on the Citroen WRC rally car for a few years and was so good it got banned. The principle behind it is to provide good roll stiffness for cornering without also being stiff for articulation movements of the suspension to allow it to easily hold an uneven road - perfect for rallying, but also very applicable for normal driving.

A articulation movement is one where diagonally opposite wheels go up/down together while the remaining two wheels stay the same or move in the opposite direction, and this happens pretty much any time the car is traversing uneven ground. A good way to visualise it is what happens if you drive one wheel of a car up onto the curb, lets say the front left wheel. We've all see cars parked this way before.

That front left wheel will be compressed, whilst the rear left wheel will be extended. On the other side you'll have the opposite, the front right wheel will be extended while the rear right wheel will be compressed. This is articulation. Another way to think of it from a roll bar perspective is that the front suspension is "rolling" to the left (left compressed and right extended) while at the same time the rear suspension is rolling to the right!

If the front and rear roll bars are not connected in any way then when you make the roll bars stiff for anti-roll, you also make them stiff for articulation, thus poor grip over very uneven surfaces. So there is always a compromise between reducing roll and reducing articulation ability.

The genius of the Kinetic system is that you hydraulically link the front and rear roll bars with hydraulic rams and pipe them in such a way that the roll bars are allowed to roll in opposite directions more or less without restriction, because the front suspension "rolling" left pushes fluid in the same direction around the loop circuit as the rear suspension "rolling" right. Thus when the wheels move in an articulation mode as you traverse uneven ground the suspension is allowed to move freely with no added stiffness from the rollbars, thus it rides this uneven ground well and maintains good grip. (Equal weight on left and right wheels)

However when the car tries to roll on a corner now both roll bars are trying to hydraulically oppose each other - the front and rear suspension both trying to roll left push back against each other and this puts the full stiffness of each roll bar into action and strongly resists roll. Voila!

Guess what other car has hydraulic rams on front and rear roll bars and hydraulically links front and rear rams together ? Yes that's right, the Activa, released years earlier in 1995....

It's been years since I last looked at the Activa ram hydraulic circuit configuration but I remember analysing it to try to work out whether it was configured to work in the same way as the Kinetic system (eg free articulation movement but stiff anti-roll) but I can't actually remember what conclusion I came to.

Whether it is configured this way or not, one thing for sure is that the Activa has all the necessary hardware to act like the Kinetic system. (hydraulic ram for front and rear roll bars, with a hydraulic link between front and rear) I must have a look at the Activa diagrams again to see if I can work out whether it is configured like this or not. If it is, it would certainly explain why it can still ride well.

Edit: for anyone about to point out that Kinetic was founded in 1989 - before the Xantia Activa was released in 1995 I'd point out that the original Citroen Activa prototype car was also produced in 1988. The Xantia Activa was only the commercial realisation of a system that Citroen had demonstrated in working prototypes 7 years earlier. In fact the original Activa prototypes were considerably more sophisticated than what ended up in the Xantia Activa, for example I'm pretty sure it had double wishbones and not McPherson struts.

[Stickyfinger]

The disappointing thing to me is that after the Xantia each generation of Hydractive got more sophisticated (especially the C6 and C5 X7) and they even returned to double wishbones instead of McPherson struts... but they kept tuning the suspension stiffer and more sporty with each model to keep up with the Joneses! So you end up with a system that is really clever and could potentially ride very well and handle very well with a lot of flexibility in between, but then you throw it all away by tuning it so firm so that it doesn't ride that much better than coil springs...

I think a soft wafty ride is simply "out of fashion" at the moment in the driving populace, hence Citroen's gradual tuning towards more and more sporty to keep up with (mostly) their German rivals, and now abandonment of Hydractive altogether, after the cost/benefit equation no longer makes sense. (Why have all the extra complexity and cost if the ride isn't that much softer) In essence, Citroen forgot the roots of Hydro-pneumatic which was always ride comfort.

I agree with every single part of what you have said Simon, you are spot on.
Nothing has compared to the GS or CXs I owned - even the XM, of which I had 3, never did it for me The XMs (without comfort spheres - and I'm guessing that's why those were introoduced!) - never had the supple ride of the GS or CX (I never owned a BX, but I'm sure they were fine too). I found the XMs too jerky and the the ride at low speed <30 could be bumpy, but moreso, I found that these could have 'good' days and 'bad' days - sometimes it would ride perfectly and other time it would jerk over the smallest pebble.

The electronics surely have to be the cause - without these the fluid and gas just react naturally - start intervening and adjusting the damping / springing and I just don't think the system can react quick enough - as let's face it by the time the car has decided this is a bumpy bit of road and we better adjust things - you're over it allready!

You can turn a C5x7 Tourer into a soft floaty car by putting 400kg in the boot with the back seats down, it transforms the cars suspension.
Has anybody "comfort modified" a C5x7.

Early Rear Anti Roll Bars where thinner btw, the change in them (increased stiffness) has been to harden the ride in an attempt to cure the "sick rear passenger" effects that some people were reporting. Never had any comments from passengers in mine btw.

As less and less people understand cars, less know the truth behind those stories of horror that "sold the myth" of problems with Citroen Suspension, mass marketing against you and poor defence of it has killed off the most technically suitable suspension for Estate cars let alone other types. People, who would have em ?.......phaf

[GiveMeABreak]

You can turn a C5x7 Tourer into a soft floaty car by putting 400kg in the boot with the back seats down, it transforms the cars suspension.
Has anybody "comfort modified" a C5x7.

I'm sure there will be somebody who attempts it - although I did see a video showing somebody who had put the Xantia green speheres on a MK1 C5! Obviously not in this country! Wouldn't like to guess what issues that would possibly cause.

You're right about the rear weight - has always seemed to settle them down.

[white exec]

One acid test is the reaction of passengers to being driven in a decently serviced hpn Citroen. Never had anyone complain of rear seat sickness in either our soft and non-sporty BX, nor the current XM. We have many friends quick enough to comment on the qualities of an unfamiliar vehicle, and all of them are remain impressed by the XM's ride, comfort, finish and space - the more so for something now 20 years old this year.

_______

Alasdair is right about fewer and fewer people understanding cars; they just expect them to work, and that's it - perhaps not unreasonable if you've just bought a new one.

But blissful ignorance can be a bit painful. Some good friends of ours recently took delivery of a brand new Renault, and collected us one evening to head out to a local restaurant, which involved a few km of rural tracks and indifferent concrete roads. The ride was unbelievably harsh (even 4-up) but we were a bit too tactful to say so. To cut a long story short, several weeks later they were, apparently, seriously thinking of giving up on the car, returning it to the dealer, and looking for a replacement. Discussions with the dealer followed. I then discovered (while helping out with a locally-sustained puncture) that the vehicle's tyres were grossly over-inflated: all at something approaching 3 bar! I suggested that we drop them to the recommended pressures, but was surprised by the reaction, "It's a new car, and we'd better not do anything like that." What??

Well, the pressures were dropped (I did it while the owner wasn't looking), and the ride improved no end - as it would. But it says a lot about an owner of a new car, and lots more about the dealer.

They did finally get rid of the car. Decided they didn't like the lack of interior space, or the colour, or the poor torque, or the lack of any spare wheel. Renault didn't totally lose out - they bought another - but took a hit on the trade-in. This time - wait for this - they took it for a test drive. And opened the boot.

[vborovic]

I fail to see how a comparison with older Citroen's will help X7 owners in determining whether or not their suspension is normal (what's "normal" for it is also a mystery in itself) ... I know people who owned, own or had access to different Citroen cars over the years, from the DS (original) to the latest ones, hydractive ones ... the general consensus is that the later models became more stiff, with the main point having a firm suspension to better grip the road surface, as opposed to the "carpety" ride like the CX i.e. offers ... the HA3+ is quite different to anything before it, in a sense that you can't know or influence what the ECU does (the sport button may or may not give you a stiffer suspension) and which sensors it feeds off from (if at all, I've personally witnessed a car which didn't throw any errors until we directly tested it bit by bit with Lexia, by running individual tests for each suspension segment) ... and, since the Citroen wanted to appeal to the Germans (and similar car buyers), they had to make it stiffer ... the irony is that now BMW, with it's Dynamic Drive (series 5, X7, etc) offer a ride of higher quality and better road handling that the supposedly perfected hydractive suspension in the form of HA3+ on the Citroen C5 ...

Of the X7 owners I know, non would be willing to testify that their suspension "works as designed", since all of them had a reference car of the C5 Mk2, and all of them claim that it has a better ride comfort (me included) ... so go figure ... my advice for all the hydractive X7 owners would be to invest a few hours, dig through every possible test and live data from the suspension, and just maybe you'll be able to trace what's wrong (in case you're certain something is off compared to what it used to be)