There’s Something Very Wrong With Citroen’s Dampers

Photo Credit: WRC+
  • FuchsrohreWRC

    Some good points raised, which makes a change from the endless drivel on many forums – were the problem is quite simple; more mistakes from Meeke. Utter garbage.

    Anybody with the faintest bit about them can tell there is a major problem with the car – and this has been obvious from Monte-Carlo. Driving at competitive rally winning/ challenging speeds makes the problem even more apparent. You might get away with it at 5-6 tenths, but why would you drive like that?

    What is slightly worrying is Citroen took last year out to test & develop their 2017 WRCar – and this is what has happened. They need to sort it out quickly, as one fears what might happen in Finland….

    • Jason Anthony

      Thanks for the kind comments! I tend to agree with you, but to be honest, Finland might not expose this problem quite as much as say Portugal and Sardinia. Yes Finland has jumps, but the rougher rallies have far more sudden and violent bumps/compressions. I even worry about them in the Mosel River stages in Germany where those junctions in the vineyards have some very fast compressions with almost no margin for error with a drop on one side and a wall on the other. The smoothness and width of the roads in Finland might mask the problem and save them. We’ll see! Thanks for your thoughts!

      • I don’t think you’ll need to worry as much for Tarmacadam rallies. Following the logic of your theory; By Eyeball the C3 looks quite tall & tottery. Combining that with this years aero load, which presumably varies a lot with speed, would require progressive damping – leaning on the damper to allow for the softest possible spring. Possibly not enough progression in the damping under prolonged high speed bump conditions could result in digressive damping (jack down).

        It could also be very sensitive to pitch at larger yaw angles – the tall greenhouse puts the rear wing in its wake. It’s likely the splitter may be similarly sensitive at yaw – under roll it’ll see bigger variation in angle of attack than in pitch.

        So why will it be ok on tarmacadam? There’ll be far less travel so roll & pitch changes will be smaller and the underbody aero more effective at lower ride height. The yaw angles are much smaller on tarmacadam. Finally the spring rates are higher so will do more of the work maintaining ride height & effective springing even under peak aero load. The roll couple will be shorter in tarmacadam trim too.

        I could even guess at a problem with bypass stages in the damping stroke being mismatched, perhaps.

        Whatever it is I don’t think it’s a massive flaw. More likely a set-up compromise exacerbated by the aero. What would have been a sketchy moment in the past is now a likely binning. They’re generating higher lateral loads now so when a tyre doesn’t stick as desired things get away from them much quicker. As it gets away from them the aero falls away. Again by eyeball, the side ‘sail area’ puts the centre of pressure not far off the yaw centre so not much help in straightening it up. When that aero goes away it’ll also sit up on its suspension – tempting a roll when it bites or squirting towards the scenery when the road comes up to meet the car.

        But that could all be confirmation bias. I suspected the radical aero this year would pose some throw up some cliff-edge scenarios. Fun bit of supposition though, Thanks Jason.

  • Xavier

    I don’t think dampers have much to do in the case of Kris’s crash in SS4 and SS14: If you drive over rock the size of a football (like the one we can clearly see he ran over when pausing the HD video) you gonna wreck, no matter the dampers.

  • CL

    >At high speeds, the increased down-force is keeping the suspension in a compressed state. When a compression does appear in the road, the dampers are already under so much load that they are unable to compensate for the bump and the car reacts in a very strange and unpredictable way.

    That’s not how that works. Dampers only generate force when they move. When static, whether they are full compressed, fully extended, or anywhere in between, they exert effectively zero load. So if we picture the car on a perfectly smooth road, you can have zero downforce or have 1000lbs of down force and as long as the damper is static it will produce no net force on suspension. The chassis however will find equilibrium in ride height, and that depends on ride height, motion ratio, and spring rate.

    Now you could make the argument that they are under sprung or running too low under downforce, but the dampers have little to do with this. Bumps are also high speed compression, body roll and pitch are controlled by low speed, spring rate supports the car. The accident occured under a high speed compression, so maybe they need more/less high speed damping, but that will have a net zero effect on the chassis during downforce periods. The only way to control the chassis under low velocity wheel movement like downforce is spring rate unless of course you have metered shocks or active suspension, neither of which get used in rally to my knowledge.

    Also, as lower ride heights produce better under body performance there’s a good chance they are just running too low in an attempt to make better grip, get better tire life, etc.. Suspension doesn’t do much good if your chassis is on the ground. A formula 1 car for example supports the car under heave with a third spring, this lets them tune the spring rate for heave generated by downforce directly and separates spring rate from roll. Rally cars do not have this advantage, so they are looking at either running the cars higher but with soft springs or lower with stiff springs. Compromise is wakes makes chassis setup so difficult. And if you look at the M sport cars, specifically Ogier, they are stiff and low for the most part. The Toyota is the opposite, the Hyundai and the Citreon are nicely in the middle. Meeks offs of course are nobody but his owns fault in my opinion. He needs to find 98% of full pace for a bit and finish a rally.

  • Gary Beecroft

    An interesting article with many good points but I think you are mistaken with regard to the effect of downforce. The downforce load is taken by the springs not the dampers. On a perfectly smooth road there would be zero load on the dampers from downforce. However not many rallies are held on smooth roads, and if the springs are loaded by downforce then the damper rates will have to be set higher to control the wheel movements.

    Its an interesting idea that Citroën’s problems are caused by damper problems. It could also be caused by having insufficient wheel travel for the rougher roads. Or driver error.

  • Jack Barret

    you obviously don’t know anything you’re talking about SS14 crash had nothing to do with the dampers, and you can deduct everything just from looking at videos and not actual data?

    I call complete BS on this

  • Arlan Santos

    don’t know much about mechanical setup but i think citroen has adopted a very stiff and edgy suspension setup good for race tracks but easily gets upset on bumps similar to their wtcc cars. See the proof with the rally Spain results, the car is a beast on tarmac.

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