Ride quality...is it my imagination....

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

Moderator: RichardW

User avatar
Paul-R
Donor 2023
Posts: 6916
Joined: 07 May 2009, 16:24
Location: Wirral, NW England; Vaucluse 84, France
Lexia Available: Yes
My Cars: 2015 1.6 Blue HDi 120 Peugeot 308 Active SW
2013 2.0 HDi 163 C5 Exclusive Tourer
2003 2.0 HDi 110 C5 Exclusive Estate (Gone)
2001 2.0 HDi 90 Xsara Estate (Gone)
x 1369

Re: Ride quality...is it my imagination....

Post by Paul-R »

white exec wrote:... Rover P6 rear suspension ... a deDion tube.
And, IIRC, a proper Watt Linkage rather than a cheapo Panhard Rod.
white exec wrote:...An absolute gift to learners needing to do a good hill-start: with the handbrake on, you let up the clutch until it bit, and down went the rear end; release the handbrake, the rear end went back up and the car went forward - never failed.
That's because of the trailing arm rear suspension. If Xantias, C5s, etc had had the handbrake at the rear instead of the front you could have done the same.
As I get older I think a lot about the hereafter - I go into a room and then wonder what I'm here after.

Inside every old person is a young person wondering what the hell happened.

"Trying is the first step towards failure" ~ Homer J Simpson​
User avatar
white exec
Moderating Team
Posts: 7445
Joined: 21 Dec 2015, 12:46
Location: Sayalonga, Malaga, Spain
My Cars: 1996 XM 2.5TD Exclusive hatch RHD
1992 BX19D Millesime hatch LHD
previously 1989 BX19RD, 1998 ZX 1.9D auto, 2001 Xantia 1.8i auto
and lots of Rovers before that: 1935 Ten, 1947 Sixteen, 1960 P5 3-litre, 1966 P6 2000, 1972 P6 2000TC, and 1975 P6B 3500S
x 1752

Re: Ride quality...is it my imagination....

Post by white exec »

Always amazes me how straightforward a hill-start is in an XM, with four pedals to play with. Like walking up stairs, it's best not to try to follow what each foot is doing, just get on with it. Having an engine that is reluctant to stall (ECU-maintained idling speed, within reason) is a great help!
Chris
Peter.N.
Moderating Team
Posts: 11563
Joined: 02 Apr 2005, 16:11
Location: Charmouth,Dorset
My Cars: Currently:

C5 X7 VTR + Satnav Hdi estate Silver
C5 X7 VTR + Hdi Estate 2008 Red

In the past: 3, CX td Safaris and about 7, XM td estates. Lovely cars.
x 1199

Re: Ride quality...is it my imagination....

Post by Peter.N. »

It seemed that the foot brake came off slowly on the XM as you could stop without putting the parking brake on and if you were pretty quick about pulling away the car didn't roll back.

Peter
Online
User avatar
GiveMeABreak
Forum Admin Team
Posts: 37002
Joined: 15 Sep 2015, 19:38
Location: West Wales
My Cars: C3 Aircross SUV HDi Flair Peperoncino Red (The Chili Hornet)
C5 X7 2.0 HDi Exclusive Mativoire Beige (The Golden Hornet)
C3 1.6 HDi Exclusive Aluminium Grey (The Silver Hornet)
C5 MK II 2.0 HDi Exclusive Obsidian Black
C5 MK I 2.0 HDi SX Wicked Red
Xantia S2 2.0 HDi SX Hermes Red
C15 Romahome White
XM 2.0 Turbo Prestige Emerald Green Pearlescent
XM 2.0 Turbo Prestige Polar White
XM 2.0 SX Polar White
CX 20 Polar White
GS 1220 Geranium Red
CX 2.4 Prestige C-Matic Nevada Beige
GS 1000 Cedreat Yellow
x 5646

Re: Ride quality...is it my imagination....

Post by GiveMeABreak »

I never really used the handbrake on my last 2 XMs which were autos - had a dodgy knee, so lifting it up high enough to engage the handbrake pedal was uncomfortable - that is until the gearbox went on one of them and had to have the whole thing replaced - that wasn't much fun driving home when it started slipping trying to get up the hills! Never made it back, so had t leave it in a shop car park until I sorted the recovery to the gearbox specialists. It seemed all or nothing on it, very little warning.
Please Don't PM Me For Technical Help

Marc
lexi
(Donor 2020)
Posts: 2803
Joined: 17 Apr 2008, 17:51
Location: Scotland
My Cars:
x 138

Re: Ride quality...is it my imagination....

Post by lexi »

This one is for Chris. Note the Denso tape on the new heavy duty springs.

Image
Citroen C5 1.6 HDI 110bhp Estate 06 plate

French Mistresses gone.
Citroen C5 HDI Mk 1 hatchback
Vel Satis 3.5 v6
ZX 1.9D Est.
ZX 1.9DHatch
Xantia 1.9td est.
Xantia 2.0 hdi Est.
Xantia V6 MK1
Xantia V6 MK 2
User avatar
white exec
Moderating Team
Posts: 7445
Joined: 21 Dec 2015, 12:46
Location: Sayalonga, Malaga, Spain
My Cars: 1996 XM 2.5TD Exclusive hatch RHD
1992 BX19D Millesime hatch LHD
previously 1989 BX19RD, 1998 ZX 1.9D auto, 2001 Xantia 1.8i auto
and lots of Rovers before that: 1935 Ten, 1947 Sixteen, 1960 P5 3-litre, 1966 P6 2000, 1972 P6 2000TC, and 1975 P6B 3500S
x 1752

Re: Ride quality...is it my imagination....

Post by white exec »

Lovely! What is that from?

Remember my 1960 Rover 3-litre had its rear leaf springs wrapped in OE thin leather "gaiters". It was a service recommended that these were periodically removed (they were laced on) and graphite powder or graphite grease refreshed in between the leaves! "Just going out to grease the leaves on the Rover, dear . . ."

Front of the car was a bit easier: long horizontal torsion bars, with a simple spanner adjustment for ride height.

Everything on the car was big, including the rust problem. If only I knew then, what I know now! IIRC the car weighed in at 33cwt (1.65 tons), with a matching 33 pints (19 litres) for the cooling system, and a 20 gal (91 litre) fuel tank. Being manual, she did return about 22mpg, which some here would be happy with, it seems!

With its Connolly leather bench seat in the front, and an incredibly long-travel forward-reaching gear lever. This made driving exciting, especially when two front passengers included mini-skirted young things, in the days when.........

A great picture, lexi !
Last edited by white exec on 05 Nov 2016, 11:07, edited 1 time in total.
Chris
Peter.N.
Moderating Team
Posts: 11563
Joined: 02 Apr 2005, 16:11
Location: Charmouth,Dorset
My Cars: Currently:

C5 X7 VTR + Satnav Hdi estate Silver
C5 X7 VTR + Hdi Estate 2008 Red

In the past: 3, CX td Safaris and about 7, XM td estates. Lovely cars.
x 1199

Re: Ride quality...is it my imagination....

Post by Peter.N. »

I remember quite a few of the 'quality' cars in the '50s having wrapped springs and in the DIY world greasing and wrapping them was advocated to improve the ride and lengthen spring life.

Peter
lexi
(Donor 2020)
Posts: 2803
Joined: 17 Apr 2008, 17:51
Location: Scotland
My Cars:
x 138

Re: Ride quality...is it my imagination....

Post by lexi »

Thanks Chris.
That was from the 62 ser 11 Landy. Wooden wheels to aid moving around and then rolling under to bolt up. Crazy Tractors but fun!
Citroen C5 1.6 HDI 110bhp Estate 06 plate

French Mistresses gone.
Citroen C5 HDI Mk 1 hatchback
Vel Satis 3.5 v6
ZX 1.9D Est.
ZX 1.9DHatch
Xantia 1.9td est.
Xantia 2.0 hdi Est.
Xantia V6 MK1
Xantia V6 MK 2
User avatar
Stickyfinger
(Donor 2016)
Posts: 10411
Joined: 28 Mar 2013, 21:05
Location: Somset my lovleee
My Cars: Xantia V6 ACTIVA 3ltr 24v Manual p1
Xm 2.1TD Ph2 Exclusive
AX, little Daffodil
SAXO White Mk1. Sally
x 1280
Contact:

Re: Ride quality...is it my imagination....

Post by Stickyfinger »

Leave the wooden wheels on, you will not notice in a LandRover :)
Alasdair
Activa, the Moose Rider
3x C5x7 Steering racks and counting
Peter.N.
Moderating Team
Posts: 11563
Joined: 02 Apr 2005, 16:11
Location: Charmouth,Dorset
My Cars: Currently:

C5 X7 VTR + Satnav Hdi estate Silver
C5 X7 VTR + Hdi Estate 2008 Red

In the past: 3, CX td Safaris and about 7, XM td estates. Lovely cars.
x 1199

Re: Ride quality...is it my imagination....

Post by Peter.N. »

I thought they were early discs. :wink:

Peter
coarist
Posts: 19
Joined: 08 May 2016, 17:41
Location: Hampshire
My Cars: Citroen C5 Tourer
x 8

Ride quality...is it my imagination....

Post by coarist »

Regular spring damper system:
  • Spring
    • F = KX
      • F : Force
        X : compression/extension/travel
        K : force constant, stiffness of spring

    Damper (shock absorber)
    • F = -bV
      • F : Force
        V : Velocity (the faster the movement, the more resistance is given)
        b : damping factor (stiffness of shock absorber, viscosity of damping fluid, size of venturi/orifices)
        - : negative sign means force is always opposing direction of movement
Hydractive system:
  • Nitrogen (gaseous fluid)
    • F = K/X (approximated from PV=nRT)
      • F : Force
        X : compression/extension/travel
        K : force constant, stiffness
    Damping (shock absorbsion)
    • F = -bV
      • F : Force
        V : Velocity (the faster the movement, the more resistance is given)
        b : damping factor (stiffness of shock absorber, viscosity of damping fluid, size of venturi/orifices)
        - : negative sign means force is always opposing direction of movement
Regular spring damper system:
  • Spring: K fixed, X directly proportional to F
    Damper: b fixed
Hydractive system:
  • Spring: K can be selected (engage or isolate spheres), X is inversely proportional to F
    Damper: b can be selected, there are 16 values to select from
"Firmness" of suspension
  • To firm up a suspension, generally both the stiffness of the spring and the resistance provided by the damper (shock absorber) are to be increased - larger K and larger b. The branch of physics that study spring-damper system is "mechanics". Firming up the suspension has two effects. (1) Shift the resonance frequency higher (2) spread the resonance peak so it is not as narrow. At higher speed the wheels pass along road surface faster therefore the frequency of vibration to be absorbed increases. Firming up the suspension trade off ride comfort at lower speeds whereas on a soft setup the system can oscillate (low damping). It is always a compromise between stablity at speed and passenger comfort. On the Hydractive system, the "spheres" substitutes spring, and the damper is similar to standard dampers only the fluild is now part of the overall LDS circuit and can be withdraw or inserted.
"Lowering" of suspension
  • Lowering the suspension is perceived to give a more "aggressive" look to the vehicle. When a vehicle is "lowered", the "travel" of the suspensiion will be reduced. The distance by which the wheel can "travel" upward before coming into contact with the wheel arch is reduced. Usually bungs or stoppers are fitted within the linkage system of the suspension. However, this is still not desirable as such device operates outside the spring-damper domain. Furthermore, they are designed for coming into play relatively infrequently. Therefore, suspension lowering should be accompany by firming up.
  • We can also look at the topic in the reverse sense. Firm suspension gives good stability at speed (sportiness). The firm spring-damper imposes stricter limit to wheel travel. By extending (trading in) the range of speed that our car can handle, we narrows down (trades off) the height of road surface features and objects that our car can roll over. At higher speed, aerodynamics becomes increasingly important. The firm suspension having imposing a narrower limit to wheel "travel" provides the properties necessary for lowering the car for improved aerodynamics.
Comparison of spring
  • On the Hydractive suspension, spring force is inversely proportion to compression. It is best illustrated by considering the limit of travel. On a metal spring, if the force is large enough, at the moment that the spring is fully compressed, the motion will hit a rigid stopper.
  • On the Hydractive system, the more compressed the gas, the more force will be required to further compress it. This is like a progressive stopper. We will not experience an abrupt step change like coming into contact with a solid obstacle. Gradual change of hardness can better absorb impulses on the suspension components so things like bushes should last long, at least in theory this is so.
  • This non-linearity reduces the possibility of harmonic frequency.
  • The springy component of Hydractive suspension has the shadow of, and feels like a refined version of, the original Mini Cooper on which similarly non-linear rubber bungs are used as springs. This quality is distinctive and the author can perceive it on the vehicle.
  • Multiple spheres that can switch in and out of the fluid circuit adds the ability to vary K. The range of softness/hardness is extended. Where the engine is located in the front of the car, weight on the front axle will not change too much. The load on the rear axle, however, will vary alot due to different number of occupant in the vehicle and different amount of luggage carried by the vehicle. On the rear axle the variation is more significant therefore we deduced the reason for an extra sphere on the latest Hydractive III system.
Comparison of damping
  • On the Hydractive III, damping factor b can assume any one of 16 values. While the adjustable damper is not such a rare commodity, on the Hydractive III damping is selected electrically. b is changed in a dynamic fashion. In addition, b can be updated very frequently. According to literature, b can be changed many times a second. The Hydractive system can adapt to different conditions. It is an adaptive suspension system.
  • With sensors, electronics, actuators, software and algorithm, each of the 4 struts can be tuned independently and on-the-fly. To get a feel of this adaptiveness, we can consider the possible combinations 16 raised to power 4 = 65 thousand. The number is itself not too meaningful save conveying to us the sense of adaptiveness.
Temperature
  • All materials (both metal spring and Hydractive fluids) are affected by temperature. We quoted PV=nRT for Hydractive nitrogen gas. Through approximation, volume of nitrogen V is roughly proportional to T which is temperature in degree Kelvin. As a crude estimate, one degree Celsius will result in a difference of 1/300 change in gas volume. Gain and dissipation of temperature may be relatively gradual. By nature, automatic ride height adjustment includes compensation of temperature on the fluids.
  • We quoted PV=nRT for Hydractive nitrogen gas. We said above that V is roughly proportional to 1/X. As we compress a gas, both the temperature and the pressure increases at the same time. When the Hydractive system is in use, the gas goes through cycles of compression and expansion. Its temperature will go up and down at the same time as the pressure. T part-take the "burden" of V. the inverse relationship between F and X is only an approximation and it should not be taken in the strictest entirety of the context.
  • The Hydractive system uses two fluids: gaesous nitrogen (spring) and liquid LDS (damping, Hydractive III and III+). Damping dissipates kinetic energy by converting it into heat. Like a conventional damper, the LDS fluid gains temperature when our car is in motion. Heat (temperature) transfers between LDS and the nitrogen gas. The volume of the gas will increase when our car is in motion, and it will reduce when we are stationary.
  • On Hydractive systems, a pair of ride height sensors are attached to the middle of the front and rear anti-roll bar. Ride height adjustment is achieved by pushing in or letting out LDS fluid in the high pressure circuit. Again, the adjustment are on-the-fly. Users also notice when the car door is opened, when the car is just parked up or when the car has been parked up, ride height adjusment activities are observed. There is a hint of sound of the LDS pump eminating from inside the engine bay, accompanied by gentle rising or falling of the vehicle to the target position.
Constant ride height
  • We have discussed the ride height adjustment due to temperature. A better known trigger of ride height adjustment activity may perhaps be change in load weight, e.g. a person boarded the vehicle.
  • When the suspension is at a lower position, the camber alters. The tyres will have a different angle to the road surface. Constant ride height maintains the optimal camber. The tyre-road contact remains optimal at all times as long as the weight of the load is within limits. Clearly there are benefits to safety, handling and durability.
  • We would like to add that constant ride height front and rear guaranteed our headlamp projection light shadow always cast at the correct angle. This mitigate the possibility of our low beam dazzling on-coming traffic. Hydractive cars do not need motorized adjustment of headlamp projection.
Novelty
  • The vehicle suspension has two configurations: separate spring-damper and coil-over type. The Hydractive system has one strut combining both functions. It can be likened to the coil-over type and it has at least the same set of desirable properties. On these struts the forces of action is longitudinal (co-axial). Bear in mind that ride height adjustment is by causing this same strut to extend or retract, the function of this strut is three-fold. (1) Spring-passive (2) Damp-passive (3) Actuator/linear motor-active. Forces act through only the two ends. In mechanics (the study of forces and motion) more than two spatially separated forces will have net (uncancelled) moment (torque). The degree of complication increases rapidly with the number of forces. It escalates further when dynamics (motions) is taken into consideration. The simplicity of one integrated strut with two pivots only on the ends is closest to ideal.
  • There are many non-conventional spring and dampers. Examples are Mercedes Benz Airmatic and ferrofluid dampers reported to be found on higher end Audi. Standing out from these examples, the Hydractive system was introduced in around 1990. It has cumulated 25+ years of utilization. Not only is such a system put together in a compact form suitable for use in regular passenger car models, but the resulting package is also practical in terms of weight and space and in terms of cost and general reliability. Hydractive would have added hundreds to component count on a vehicle. This is a shining achievement.
  • Hydractive is an hydropneumatic system. The term "hydropneumatic" symbolises the amalgamation of that to do with gases and that to do with liquid. Both gas and liquid are fluids since they both exhibit the property of flow. Pneumatics not only concerns with just flow but the compressible property is also important, too. Hydraulics concerns flow while the fluid is considered incompressible which it is.
  • When comparing Hydractive with the more commonly seen air suspensions we can pick out some lightlights. Air suspensions use an air sac usually exposed as can be found on buses and trucks. On passenger cars, the air sac although sometimes concealed it is not usually sealed. On the Hydractive, the nitrogen gas sac is placed inside metal shells famously called "spheres". The outer surface of the nitrogen bladder is in contact with the LDS fluid and it is not exposed and it is isolated from the atmosphere. Hydractive differs by
    • (1) Pure nitrogen instead of air thus the effect of oxygen and water vapor is negligible bearing in mind that both immediate result and the longer term reliability are both important
    • (2) Completely sealed and membrane-metal doubly insulated gaseous fluid thus the air sac itself does not play a part in the dynamics of neither the spring nor the damper, in terms of spring it is pure gas action
    • (3) Does not adjust the pneumatic portion but instead displaces the hydraulic fluid and thus
    • (4) uses a hydraulic pump as opposes to the air pump found on most air suspensions.
Steering feel
  • The last and latest Hydractive III+ spring-damper on the C6 and C5-X7 is combined into (is incorporated with) front double-wishbone and rear multi-link mechanical linkage.
  • On the front, the caster angle is not large. The upper wishbone is pivoted near the highest position inside the wheel arch achieving maximum allowable distance between the upper and the lower wishbone. On the wheel side, the pivot (ball joints) are positioned into the depth of the wheel. This pair of universal joints gives a steering axis at (or near) the centre of the wheel.
  • Manufactuer's literature suggested the steering function is decoupled from the other suspension actions. Many reviews commented that the steering is lacking a direct road feel. Interestingly, the reviewers added that the car is able to follow the command from the steering wheel in a way that is better than the user expectation. In other words, the car sticks to the road. Since the road feel is detached, the user drawing in experience from other cars might have obtained a perception and the tendency to under-estimate the tracking capability of the car. Still more interestingly, there was a posting on the Internet describing the Citroen C6 going round a fixed circle faster than other cars adding to it that the speed that this C6 was able to do had been significantly higher.
  • In the author's experience, the steering feel of the C5-X7 is in an extent similar to that of the Mercedes Benz W140 S-Class provided that the dissimilarity of the two can be forgiven.
Ride quality - scope
  • One aspect of quality of ride is steadiness of motion. Size is the governing factor. Width and length of the wheel base, height of the vehicle (CG) and mass and weiight distribution ... a range of factors define the underlying limits of ride properties. For example, a bus journey offers the ride quality that can be used as a reference level for passenger cars. The closer the ride quality of a vehicle to that of a bus, the higher the rating that ride should be.
  • Ride quality is not fully quantifiable. It is particularly so since it is associated with our sensation of motion. There are six quantities divided into two groups. The 'linear' group comprises heave, sway and surge. The second group, the 'gyro' group comprises pitch, yaw and roll. In terms of steadiness on the Hydractive, once again, we base our discussion on the C5-X7. It is generally accepted that the Hydractive III+ is at least no worst than prevailent form of suspension.
Ride quality - pitch
  • Pitch is one of the great aspects of Hydractive III+. For example, when creeping over speed bumps there is the usual heave but pitch seemed to be absent. The action is clean and void of other induced motion. In the author's opinion this attirbutes to the double wishbone layout. Examples of cars exhibiting similar properties include earlier Honda Civic, Honda Accord, Toyota Mark II, Mercedes Benz W211 E-Class. These cars all gave a sensation of immediate settling without following on bounces. Since these examples that gave such impressions are all of the double wishbone front geometry, the authour subjectively make a mental link to the experience.
  • When coming to a halt from very slow speed, giving the already slow stopping an abrupt braking, it is only in this specific condition that the front of the car dips - the sensation of a super-soft suspension. This seemed to be the sole opportunity to get a "sign" of how soft the Hydractive III+ can actually be. Otherwise, in normal stopping however gentle or harsh there is no pitch (no front dipping) at all. This is believed to be the Hydractive system sensing and repsonding to braking and the front suspension both spring and damping have been hardened up accordingly.
  • Should the user wish to experience the hardness of the dampers on the C5 X7 Hydractive III+, it can easily be done by choosing and driving in any of the "low", "high" and "highest" positions other than "normal". When the vehicle speed reaches or exceeds the limit that the ride height allows, e.g. 25MPH, the car automatically resets to the "normal" height and suspension resumes "Auto" or "Sport" mode.
Ride quality - roll
  • Of these aspects, roll needs most clarifying. The Hydractive III+ maintains level in corners bends and roundabouts at least as good as the norm. There is no excessive sideway tilt or body roll or leaning when tracking a radius. Remember that there are both front and rear anti-roll bar which control this. On the Hydractive III the anti-roll bars are the same as it would be on a conventional system. In addition, on the Hyrdactive III the control system would have firmed up the far side struts by sensing such activites - steering wheel rotational speed sensor, steering angle sensor, road speed data., etc. Control of body roll on Hydractive III should therefore be better than regular implementations.
  • Roll, in terms of the sensation of rocking motion to the car occupants, appeared to be a subject need resolving. On left-right asymmetrically uneven road, as the car travels, there seemed to be more depth in the cradle motion. Put it in another way, conventional systems when in the same conditions perhaps rock shallower. Furthermore, on the Hydractive III many other aspects are calmful making this deeper sideway rock motion stand out even more. For those who are sensitive to it, the "Sport" mode on the Hydractive III is found to give an improvement. By same-model upgrade, the author finds having lower profile tyres (larger alloy wheel size) reduces the magnitude of this rocking, too.
  • Theoretically, for the same left-right asymmetrically uneven road surface, the amount of rocking energy is the same. It is either a "shallow" rocking with higher force or a "deeper" rocking with more gentle force. Torsion in the anti-roll bar seemed to be the key factor.
  • This wobble has been discussed in forums including postings from Australia. One of the posting said the passenger who is the spouse of the blogger resent this characteristics of Hydractive III. As a side note, the latest Bentley Bentayga has "active" anti-roll bar. Being a tall vehicle (SUV body style), it has higher tendency to give such rocking feel. The active anti-roll bar has an electro-mechanical coupler in the middle. When the vehicle is travelling straight, the coupler disengages. Reportedly Bentley cars use Hydractive type of strut (sphere on strut). This example demonstrated a potentially perfect complement to Hydractive III.
Ride quality - general
  • Any suspension system uses bushes. These components are usually compliant they can give and take a little bit when under force. Working in conjunction with the tyres, they absorb certain small displacements and they work outside of the domain of the spring-damper system. Small uneveness on road surface tend to be absorbed in larger proportion by the bushes. Hydractive III, due to the property of gas compress relatively easily in the beginning (non-linear F = K/X) seemed to extend the effect of the "rubber" bushes. When driving over dens that are only surface deep, vibration is not felt at all. Despite being quite particular, the case does happen from time to time and in daily use. In this respect, it is true to the "magic carpet ride" decription. Incidentally, the F = K/X model applies to rubber the same way as it is applied to nitrogen gas the Hydractive spring fluid.
  • Overall, the Hydractive III+ conveys a sense of serenity and confidence. Bearing in mind that it is a self-adaptive system, the envelop of operation is enwidened. Our suspension can maintain optimal in a far wider range of conditions as opposed to a single sweet spot. The primary factor is speed. The Hydractive III+ when in operation gives no clue to the user that it is functioning. Its operation is almost completely transparent to the user. Like the ABS or the ECU, they are working in the background. Unless there is a fault, we need not be aware of them.
  • And the same applies to the "Sport" button. The effect of switching to "Sport" is subtle. From relevant literature, the sport mode is said to lower the trigger thresholds (to parameter inputs). We expect the Hydractive III+ goes firmer when the condition arises. In daily use, one has to look for such difference otherwise they just go unoticed. In this discussion it is proposed that "Sport" better subdue side-to-side rock on left-right asymetrical bumpy roads.
Conclusion
  • To best summarise the Hydractive system, we say: (1) Gas spring (2) adaptive damping (3) adjustment by hydraulic displacement. In terms of the feel of the spring action, the bouce and bump absroption characteristic reminisces the ride on the Mini Cooper.
  • The prevailing, quite well-accepted, notion for Hydractive is the "magic carpet ride". The magic carpet is told in the story of One Thousand And One Night as a flying carpet that can transport people between places. There is imagination, mystery, excitment, discovery and romanticism. All of these qualities are not the domain of language or words. No wonder even professional journalist when handling the subject of evaluating and reporting on the topic often showed limitations. In the author's eye it is natural and human. We all can have different ideas and understandings about these qualities. The values that we place on them are inevitably different. It is a very personal thing. As such, Hydractive has a high potential of being contraversial particularly in the sense that ideas about it can vary and has a likelihood of being disagreed upon.
  • There is a problem of "reference". For a regular car that is not so different, perhaps a new model with newer technology lighter and stronger, there are numerous models that we can draw upon to aid understanding. For example, if we mention our new car model bringing in "Fiesta" everyone gets it that our subject has similar attributes such like the size, the popularity, the price bracket and more. One such mention is worth a thousand words. "Fiesta" in this example is taken as a reference with which everyone can easily make a mental association.
Hydractive
  • Oleopneumatic suspension:
    • Earliest incarnation
  • Hydractive:
    • + electronic control
    • + ride height select
    • + "Sport" mode
    • + extra sphere (total 6)
  • Hydractive III:
    • + control laws (computer control)
    • + electric pump
    • + constant (auto) ride height
    • + change to LDS fluid
    • + rear extra sphere (total 7)
  • Hydractive III+
    • + auto front lowering 15mm at around 70PHM.
    • The C5-X7 Tourer has a switch on the boot wall for raising and lowering the rear - a convenience for loading the boot.
Last edited by coarist on 11 May 2017, 00:54, edited 32 times in total.
User avatar
white exec
Moderating Team
Posts: 7445
Joined: 21 Dec 2015, 12:46
Location: Sayalonga, Malaga, Spain
My Cars: 1996 XM 2.5TD Exclusive hatch RHD
1992 BX19D Millesime hatch LHD
previously 1989 BX19RD, 1998 ZX 1.9D auto, 2001 Xantia 1.8i auto
and lots of Rovers before that: 1935 Ten, 1947 Sixteen, 1960 P5 3-litre, 1966 P6 2000, 1972 P6 2000TC, and 1975 P6B 3500S
x 1752

Re: Ride quality...is it my imagination....

Post by white exec »

That's an interesting and detailed perspective on Hydractive vs conventional and other springing, and makes for a very different sort of read. All your own words, or extracted from other articles? Whichever way, it's a good description.

Interested in the brevity of your section on 'Ride quality', which looks as if you were about to write much more...! Please do expand this bit.

(Took me back to a line from a physics (mechanics) teacher I had at school, who, when working on Forces, always enjoyed reminding us that "Every Couple Has its Moment" . . . :? )
Chris
coarist
Posts: 19
Joined: 08 May 2016, 17:41
Location: Hampshire
My Cars: Citroen C5 Tourer
x 8

Ride quality...is it my imagination....

Post by coarist »

Hi thanks for feedback and comment. It was unfinished and I meant to save the draft. Instead I pushed the Submit button. Anyway, if everybody don't mind, I will attempt to finish up by updating the post directly.
No part of the text is copied. All my own words (therefore a bit clumsy). It is a prespective and there is also the subjective element in it.
User avatar
white exec
Moderating Team
Posts: 7445
Joined: 21 Dec 2015, 12:46
Location: Sayalonga, Malaga, Spain
My Cars: 1996 XM 2.5TD Exclusive hatch RHD
1992 BX19D Millesime hatch LHD
previously 1989 BX19RD, 1998 ZX 1.9D auto, 2001 Xantia 1.8i auto
and lots of Rovers before that: 1935 Ten, 1947 Sixteen, 1960 P5 3-litre, 1966 P6 2000, 1972 P6 2000TC, and 1975 P6B 3500S
x 1752

Re: Ride quality...is it my imagination....

Post by white exec »

Don't apologise for the text - it is very well written.

Glad I'm not the only one to hit the wrong button, sometimes. Wish there was an auto-save option; I've lost count of the number of times something lengthy gets lost. Tend to do such things in Word now, and paste into the forum.
Chris
lexi
(Donor 2020)
Posts: 2803
Joined: 17 Apr 2008, 17:51
Location: Scotland
My Cars:
x 138

Re: Ride quality...is it my imagination....

Post by lexi »

If anyone is familiar with the Rannoch Moor road, built on peat, that is where hydractive is at it's best. Damping on a road that undulates on all planes. The surface is scarred where towbars have marked it through grounding. Even my basic 4 sphere C5 hydractive, exudes confidence when rattling along there, soaking the lot of it up in a way that is very satisfying.
Citroen C5 1.6 HDI 110bhp Estate 06 plate

French Mistresses gone.
Citroen C5 HDI Mk 1 hatchback
Vel Satis 3.5 v6
ZX 1.9D Est.
ZX 1.9DHatch
Xantia 1.9td est.
Xantia 2.0 hdi Est.
Xantia V6 MK1
Xantia V6 MK 2
Post Reply