Hydractive 3+ on C5 X7 really hard when not at normal height

This is the Forum for all your Citroen Technical Questions, Problems or Advice.

Moderator: RichardW

Jay-Bruce
Donor 2022
Posts: 50
Joined: 20 Mar 2019, 01:30
x 28

Hydractive 3+ on C5 X7 really hard when not at normal height

Post by Jay-Bruce »

I don't know if this is normal, but when I put our X7 to any of the higher height settings the ride becomes really hard. Most of my citroen experience is on BX's, and due to the much simpler suspension system it was always compliant, regardless of what height you put it to. I was thinking about it, I was wondering if the Hydractive 3 locks out the comfort spheres when not at normal height? If it does, to me this seems counter intuitive, it's like when you'd want the comfort most it's taken away from you:

Driver: "oh look, I see a bumpy section of road ahead, I'll raise the ground clearance"
Car: "What's that you say, a rough road requiring raised ride height? Have sports mode dampers; that'll teach you for taking me onto sub-optimal roads."

I'd also wondered was it just a sign that my spheres were getting tired, but having just changed all 7 it's still doing the hard bouncy thing at height, much to my annoyance. Is this the way it's meant to behave or do I need to interrogate the suspension ECU with Lexia?
Hell Razor5543
Donor 2021
Posts: 12402
Joined: 01 Apr 2012, 09:47
x 1652

Re: Hydractive 3+ on C5 X7 really hard when not at normal height

Post by Hell Razor5543 »

Just a thought. The electronically managed suspension will adjust the height automatically depending on the road conditions. As I understand it, at speeds over 62MPH (100KMH) on a smooth road (it would be silly to go that fast on a rough road) the suspension lowers by 15mm, while at speeds less than 37MPH (60KMH) on an uneven road the suspension raises by 20mm. The suspension will return back to its reference height as and when conditions permit (assuming it was set to 'Normal' ride height). This means you may be confusing the suspension by over-riding its settings.

http://www.citroenet.org.uk/miscellaneo ... cs-13.html

However, if you are driving over really rough ground you want the suspension in 'Sport' mode, so that it does not bottom out (if it was in 'Normal' mode it is conceivable that, should you hit a large lump, the car could momentarily bottom out on said lump).
User avatar
GiveMeABreak
Forum Admin Team
Posts: 28088
Joined: 15 Sep 2015, 19:38
x 3393

Re: Hydractive 3+ on C5 X7 really hard when not at normal height

Post by GiveMeABreak »

Jay-Bruce wrote:
07 Apr 2022, 17:49
I don't know if this is normal, but when I put our X7 to any of the higher height settings the ride becomes really hard. Most of my citroen experience is on BX's, and due to the much simpler suspension system it was always compliant, regardless of what height you put it to. I was thinking about it, I was wondering if the Hydractive 3 locks out the comfort spheres when not at normal height? If it does, to me this seems counter intuitive, it's like when you'd want the comfort most it's taken away from you:

Driver: "oh look, I see a bumpy section of road ahead, I'll raise the ground clearance"
Car: "What's that you say, a rough road requiring raised ride height? Have sports mode dampers; that'll teach you for taking me onto sub-optimal roads."

I'd also wondered was it just a sign that my spheres were getting tired, but having just changed all 7 it's still doing the hard bouncy thing at height, much to my annoyance. Is this the way it's meant to behave or do I need to interrogate the suspension ECU with Lexia?
I think you'll find the earlier systems were also less compliant when raised as there is less travel for the strut once extended. The same applies to the X7, although the suspension is a lot firmer anyway, being a later design. There is less pitching and rolling.

The system automatically switches between normal and sport mode according to road conditions AND driving style. There are a sequence of complex calculations going on that determine the frequency and time that sport mode engages, linked to the trajectory, acceleration, braking, steering angle and the road conditions of course. Engaging Sport mode will just lower the thresholds at which sport mode engages, so it stays in that mode for longer than on automatic.

Comfort or Normal suspension mode uses all spheres and whenever sport mode is engaged it switches out the 3 central spheres.
aerodynamica
Donor 2021
Posts: 1098
Joined: 26 Dec 2007, 19:10
x 58

Re: Hydractive 3+ on C5 X7 really hard when not at normal height

Post by aerodynamica »

The hydractive 3+ system is really simpler than the previous systems: hydractive I, II and hydropneumatic. And I agree, all of them go solid when you set it to the top height which is for service and repair or for very slowly driving over obstacles.

The reason they go solid at top height is that the original mechanical hydraulic height correctors are 'closed' when the car is standing at the right height. The pressure of fluid holding the front for example, is around 90bar dep on payload etc. The available line pressure in the system's accumulator is up to 175bar and when you select top height the mechanism forces and holds the front and rear height correctors open so that full line pressure raises the suspension up and pumps it hard against the top stops. When the car is at full height the suspension remains connected to the line pressure so you have 'cut-out' pressure in the 4 suspension struts in that state. Also, the spheres, 4, 6 or 7 depending on the car, are compressed to their smallest gas volume at this 175bar pressure.

The intermediate high position however, should still feel soft unless it's set too high (too close to the maximum height)
Xantippa
Posts: 478
Joined: 05 Feb 2012, 16:51
x 26

Re: Hydractive 3+ on C5 X7 really hard when not at normal height

Post by Xantippa »

Intermediate high position is also stiffer because there´s not much suspension droop travel left when suspension is rised.