Uprading DS suspension
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Thread: Uprading DS suspension

  1. #1
    GGR
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    Default Uprading DS suspension

    Hi All,

    I'm looking at options to upgrade the suspension of my '67 DS to improve handling.

    Fitting smaller spheres would correspond to fitting stiffer springs on a conventional suspension I guess. Changing leaf valves would also correspond to stiffer shock absorbers. What is the experience of forum members in this regard? Spheres and leaf valves from what cars?

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    Are there bigger diameter sway bars I can fit on my '67 21? Are station wagon sway bars bigger? What about the SM ones? can they be fitted on a DS?

    Finally, I guess I can drop the car by one inch or two by adjusting the height. Any negative side effect to be expected from this?

    Thanks!

  2. #2
    UFO
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    CitroŽn Tragic UFO's Avatar
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    Leave it alone. Tinkering with the original design always leads to failure. Driven properly a DS will handle just as well as any modern car with the same available power.

    Deliberately running the car at a lower height serves no purpose, will make it uncomfortable and also lead to premature wear of components such as bump stops and in severe cases it could lead to damage to the front brake discs or engine sump as the car bottoms out in a dip.

    Also, don't be tempted to try to "upgrade" the cooling system. That also ends in frustration and tears.
    GreenBlood likes this.
    Craig K
    2009 C5 HDi Exclusive

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    Fellow Frogger! badabec's Avatar
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    Hello, as UFO said, leave it alone.

    Have you driven the car fast around all types of bends? I often drive like a hooligan, I leave following cars for dead. The car always feel sure-footed and planted to the road, even if my wife ends up on my side of the car.

    If you change one thing, reckon on having to change seven other things. And then seven more. Until you put it back to standard.
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  4. #4
    GGR
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    Thank you for your insight.

    I've been driving DS since I'm 18, long years as my sole daily driver, and I'm over 50 now.

    I may give a bit more details on my project. I will be reproducing a CX turbo2 engine mixing DS and CX parts. The transmission will also be longer legged by combining the "long" ID transmission with a C35 diff. The objective is a long distance comfortable travel car, not a racing car. A car that would be equal to a Jaguar XJ6 or a Mercedes W109 3.5.

    Experience with previous such kind projects tought me that homegenity among systems is more important than all out performance in each one of them. A more powerful engine usually requires upgrading transmission and diff ratios, suspension, brakes etc.

    The DS has good brakes and suspension, and I may leave them alone, at least at the beginning, to see how they cope with the added power. But I am still trying to gather some knowledge from other's experience, just to see what my options are.

    Any information and experience on various spheres, leaf valves, sway bars etc. is welcome.

    In the end I may leave it stock. But I'm still interested in hearing from other's experimentations.

    Here is another project I did:

    https://www.sl113.org/forums/index.php?topic=15521.0

    English is not my mother tongue, so please bear with me.

    Thanks.

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    About 20 years ago there was a chap in the U.K. who took his DS on the Inca Trail rally through South America and he fitted a thicker roll bar to the rear. From memory it was a square section bar. Stiffening the rear to reduce roll is a good idea if belting around corners, even more important than the front I think, but it won’t help ride comfort. The car itself is still around, it had a BX steering rack, repositioned BVH brain, flat radiator and was replumbed with flexible hydraulic hoses to the gearbox Rally Prepared Citroen DS 23 PALLAS For Sale Hampshire, United Kingdom | AutoMotoClassicSale.com . Changing the rear roll bar looks like a very simple option, if you can size it by working out the torsional stiffness that you want relative to the standard one.

    Another option worth considering is fitting an XM hydractive valve, front and rear, to stop the crosswise flow of LHM when the car starts to roll. I did that many years ago on the front of my Safari and it made a huge difference limiting the roll angle - there’s a description about halfway through this thread here Special DS23 Safari for sale . It doesn’t impact ride comfort.

    Many people run with CX spheres - GTi Turbo ones on the front will help limit roll because they have a smaller centre hole than standard CX ones, but it won’t help comfort.
    Cheers, Marc.

    1987 CX GTi T2 Maikonics
    1972 SM 2.7 carb
    1972 DS21 EFI

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    GGR
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    Thanks Marc.

    That's very interesting input. I may fit the CX GTI Turbo spheres first, as it looks the simplest and is easily reversible.

    I really like the hydractive valve idea, well in the spirit of the DS. In the other thread, you seem to say that the system could do without the 5th sphere. Could you elaborate on that? What is the use for that 5th sphere then?

    You also mention the SM has less roll than the DS. Why is that? Do they have thicker sway bars? Would they fit in the DS?

    A bigger sway bar in the back would introduce a bias towards oversteering. Nice on a track or in a rally race, not so much for normal road use.

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    Fellow Frogger! marc61's Avatar
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    Inside the hydractive valve is a simple ball valve which blocks fluid transfer left/right and right/left during roll, thatís what gives the anti roll benefit. However, the hole where the XM centre (accumulator) sphere screws in needs to be plugged to prevent fluid leakage, the simplest option being to fit a sphere or make a plug screw. Some people have done the latter, because the sphere takes up a lot of space especially if youíre looking to fit one at the rear.

    Now thereís no electrics involved or sensors/computer like on the XM to bring the centre sphere in and out of the hydraulic circuit, which makes things simple. To me thatís what makes it attractive. Alternatively you could try to copy the XM and energise the electrovalve when the car is travelling straight (soft mode) and switch it off when cornering (hard mode), in which case XM spheres could be fitted on the front suspension cylinders. These have very small centre holes so the suspension is a lot firmer when cornering, while in a straight line the XM soft mode is very comfortable because all three spheres are in circuit. Iím not sure if someone has tried that yet on a DS - it would need some form of steering wheel movement sensor like on the XM and something to give the electrovalve the right voltage (itís some PWM signal not 12V).

    The SM front arms are leading so to speak, not lagging like on the DS. My understanding is Citroen figured out some time after the DS was launched that the SM layout had less dive and roll characteristic, so adopted it on the SM. Someone knowledgeable about suspension geometries would be able to explain why the SM layout is better.
    Cheers, Marc.

    1987 CX GTi T2 Maikonics
    1972 SM 2.7 carb
    1972 DS21 EFI

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    GGR
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    That's brillant. I had started looking into it when you first mentioned it to me in our email exchanges, but I got scared by all the complication of the XM system. I hadn't realised one could bypass most of it to end up with such a simple set up. Do you think such hydractive valve could also be fitted between the front and rear suspension to counter brake diving? How would it interact with the height correctors?

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    UFO
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    Then I suggest you contact Harry Martens Limmen in Holland. What he would know about making a DS faster and handle better and the ability of components to handle it - is priceless. Harry is on here occasionally so he may see your post.
    Craig K
    2009 C5 HDi Exclusive

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