Front suspension issues
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Thread: Front suspension issues

  1. #1
    Fellow Frogger! ds21bvh's Avatar
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    Default Front suspension issues

    Hi all,

    I'm just going through a full refurbishment of my DS21 and as part of this I've replaced the front height corrector with a Citrotech one. I should say the front suspension and roll bar has been apart - I did mark all the original locations and put it back pretty much as it was.

    Now I have this kind of thing going on at the front (not my car but the same issue)....

    https://www.youtube.com/watch?v=0IstKRupkn0

    Does anyone have any idea as to cause...? I've played with the anti-roll bar link to no avail. It's like it corrects to the right height then decides that is too high and drops down again - just in a cycle.

    Many thanks in advance,

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    Mark...

  2. #2
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    1) Did you prime it with LHM? If not, it may not be damping as it needs LHM to do this.
    This should fix itself just by being driven as the air should bleed out.)

    2) Roll bar is too far one side and the corrector has some lateral force on it causing to bind and let go.
    Or the link has been moved laterally on the bar in the rebuild .. or the bar had moved in the past as the bushes wore out and the roll bar was moved to reflect that. If you now have new bushes and have refitted the bar to the correct lateral position, the link to the HC may be too far to one side.
    Last edited by David S; 12th July 2018 at 02:04 PM.

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    Fellow Frogger! ds21bvh's Avatar
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    Hi David,
    Many thanks for the reply and the suggestions.
    I just replaced it with a NOS one I had here - and it works perfectly. I've never had one play up like that.
    It *seems* the height corrector was faulty (new from Citrotech) however it may simply have been the process of removing and refitting that has reset something with the linkage...
    I know the lateral position can be important - you don't want the height corrector ball right in the channel of the link rod otherwise it will bind. Fun and games - that little distraction has wasted about 8 hours....
    Kind regards,
    Mark....

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    1000+ Posts gerrypro's Avatar
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    Quote Originally Posted by ds21bvh View Post
    Hi David,
    Many thanks for the reply and the suggestions.
    I just replaced it with a NOS one I had here - and it works perfectly. I've never had one play up like that.
    It *seems* the height corrector was faulty (new from Citrotech) however it may simply have been the process of removing and refitting that has reset something with the linkage...
    I know the lateral position can be important - you don't want the height corrector ball right in the channel of the link rod otherwise it will bind. Fun and games - that little distraction has wasted about 8 hours....
    Kind regards,
    Mark....
    Sounds to me as though the spool valve is sticking instead of sliding smoothly!
    Cheers Gerry

  5. #5
    Fellow Frogger! ds21bvh's Avatar
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    Short lived joy...! It was OK for a while now it's doing it again....!
    Changed the height corrector, fiddled with the link rod both laterally and longditudinally.....
    Completely flummoxed....
    Any clues....?
    Kind regards,
    Mark...

  6. #6
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    How much end float is there in the roll bar. You may think you have corrected the lateral position, only to find it moved sideways after the next up/down cycle and still puts lateral pressure on the HC. It won't take much to do this. Look at the pivot bush on top of the roll bar bush mount and make sure it's completely free and not poking a long way through. I have had the same problem and also changed and stripped the HC before solving it via the lateral position of the linkage on the rollbar. That was at the point of just a running chassis, so fortunately no body to remove/refit.

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    Fellow Frogger! ds21bvh's Avatar
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    Hi David,
    Many thanks for the suggestion - the pivot bush on the link rod is not sticking out too far - and it's not moving laterally.
    I spent some time looking it it cycling today - everything is moving freely, that is the movement is smooth without binding.
    It's almost like it senses the car is too low, so lets fluid in, the pressure rushes in and the car jumps up, then the car over corrects which results in the exhaust side opening way up, then the fluid rushes out again and the car drops like a stone.
    There is a restrictor wire in the exhaust pipe which on one occasion blocked the pipe completely and the car would not sink. It's like the opposite now - when the exhaust is opened the pressure rushes out and the corrector is not given the chance to slowly release fluid as it's just rushing out the exhaust.
    But why would this change - the car was running fine before...?
    Kind regards,
    Mark...

  8. #8
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    That's essentially what I was experiencing and thought too. The rise was slower than the drop. Despite the wire, if you manually operate the HC, it responds rather quickly. The reason was the valve would be in a position to start to raise the car, and the link being in the wrong place applied just enough lateral pressure on the valve to cause it to stay in that position too long. Then it would be too high, let go, overcompensate and the car dropped rapidly to repeat the cycle. If you have tried two HCs and both were filled with fluid, then the problem must be with the car not the HC. Try sliding the clamp on the roll bar for the link across to the right a few more mm.

    I was going to also suggest the restriction wire might have some impact on this, particularly if there is still air in one or both sides of the HC. It just seemed a rather long bow to draw. As these cars age, more attention is needed to that wire and whether the pipe is blocked or the wire has moved.

    There is also a pre-setting routine for setting up the roll bar drop links, which might make some difference. If that is not set correctly, the roll bar could always be under some torsion with one front wheel naturally higher/lower than the others - the three-legged table problem.

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    Fellow Frogger! ds21bvh's Avatar
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    Thanks again David - I checked the heights on both sides, the car measures perfectly level, though I will check the tyre pressures are even now I've thought about it again....I set the links rods as per the manual and had marked them both before dissassembly...
    I also tried rotating the HC ball end to square it up a bit more with the linkage - it made a small difference for a short time...then it was back to it's old tricks again.
    I'll do as you suggest and move the link rod to the right as far as it can reasonably go.
    Kind regards,
    Mark...

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    Quote Originally Posted by ds21bvh View Post
    Thanks again David - I checked the heights on both sides, the car measures perfectly level, though I will check the tyre pressures are even now I've thought about it again....I set the links rods as per the manual and had marked them both before dissassembly...
    I also tried rotating the HC ball end to square it up a bit more with the linkage - it made a small difference for a short time...then it was back to it's old tricks again.
    I'll do as you suggest and move the link rod to the right as far as it can reasonably go.
    Kind regards,
    Mark...
    The only thing I havenít seen in this discussion is whether you had primed the height corrector or run the car long enough to bleed any air. If you installed both without doing so, same result

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    Hi Peter,
    Many thanks for the response.
    I've never primed a height corrector in all the years I've been running D's - how would you do this....?
    The car has been cycled through maybe 20 odd full height full low cycles while I stuffed around with it - so I'd assume there could not be any air in the system. Happy to be wrong though if this is an issue...?
    I started with a bare chassis so all the hydraulic stuff would have air in it, but again apart from brakes and the CR I've never had an issue - I just assumed it would work it's way out....?
    The car has not been driven anywhere yet....
    Cheers,
    Mark....

  12. #12
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    Priming is in the manual as part of the HC overhaul section. RTFM I guess!

    All you have to do is peel back the dust cover and retaining rings, pull back, obviously at the top as you hold it, about an inch along the circumference of diaphragm and introduce LHM via a syringe minus the needle. Put it together and do the same for the other side. If you forget to do this, there will be little damping and delay in the suspension response because air will travel though the stack of tiny discs between the two side much more quickly than LHM. When debris builds up to the level of this connection and blocks it, this is when you see the suspension refuse to drop because LHM can't move from one side to the other to allow the valve to move (assuming it's not due to the wire inside the tube problem). Air will work it's way out after a short drive in which you may have odd suspension movements, but priming is the better solution. Alone, it probably won't explain 'nodding'.

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    Interesting...! I'll try anything at the moment... Many thanks for the heads up on the manual procedure...!

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    I think David Bourne here in the UK had a similar problem. I will try and find out more.

    Paul
    1968 DS21bvh Pallas in Gris Palladium

    Restoration blog: https://ds-restoration.blogspot.co.uk

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    I’ve seen that before with a new HC fitted to a CX, it was trapped air. Don’t remember exactly what I did to get it out, repeated bleeding of the regulator and driving it up and down the driveway I think.
    Cheers, Marc.

    1987 CX GTi T2 Maikonics
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    Air seems top be a theme..... here are some ideas from the UK:

    Problem can be solved by turning the front wheels in straight forward position, move the car a little bit or park the car backwards (180į).
    Cleaning the height corrector will not allways do the trick because a slight tension in the correctors link can cause this strange behaviour.


    This happened to me once and I turned the steering lock-to-lock several times and raised and lowered the suspension to max/min several times. When I got home I released the bleed screw for a bit and retightened. Never happened again. That last bit about the bleed screw was probably unnecessary, but just in case.


    Height corrector and control lever adjustment..this fault is common CX ..replace height. Correctors ..the ones fitted on your car might have been reconditioned and the piston shaft fitted upside down .try a used height correctot


    Air in the hight corrector chambers


    Air!


    System not bled sufficiently. Needs Citrobics a few times and bleeding at the regulator.
    1968 DS21bvh Pallas in Gris Palladium

    Restoration blog: https://ds-restoration.blogspot.co.uk

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    The problem with just driving the car, or doing calisthenics is, with a relatively new height corrector, the bypass leakage will be very little and, therefore, will require a long time to fill the valve damper. The better the rebuild, the longer it will take. Thinking out loud, it might be possible to fill the damper in place by removing the pee line and loosening one or both of the rubber covers (to allow air to escape), then injecting LHM through the nipple for the pee line. Using a piece of pee line tubing held vertically (to increase the pressure) may also help.

    Cheers,
    John T.

    54 TAV Legere; 61DS19 LHM BVH (son's); 71DS21 BVH; 73SM 3.0; 73SM EFI (Megasquirt); 73SM 3.0 (other son's)

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    Fellow Frogger! ds21bvh's Avatar
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    Many thanks David, Paul, Marc and John - I really appreciate the replies.
    I just had a chat with another friend who was sure it was air too.
    I'll refit the original HC filled with fluid and reset the linkage the way it was to start at the beginning again and then do some judicious bleeding to try and get the air out. I can't drive the car yet so that is not an option. I'll also remove the front spheres and prime the cylinders if they are not full of fluid already....
    I'm going to do some other stuff on the car today - I'll have another go on it tonight and let you know how I get on.
    Kind regards,
    Mark...

  19. #19
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    No need to prime the suspension cylinders. These are filled with high pressure fluid immediately. What you need is to prime the damper that is inside the height corrector. That is a low pressure circuit, so it needs to be primed manually. Examining the cross section drawings, I still believe priming through the pee line is a good option before you disassemble everything....
    Cheers,
    John T.

    54 TAV Legere; 61DS19 LHM BVH (son's); 71DS21 BVH; 73SM 3.0; 73SM EFI (Megasquirt); 73SM 3.0 (other son's)

  20. #20
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    Here is what I mean. The "restricted passage" needs to be full of fluid or the slide valve will move too easily (no damping). Since the "restricted passage" is connected directly to the pee line (overflow) you should be able to introduce fluid here.

    Front suspension issues-heigh-corrector-xsec.jpg
    Cheers,
    John T.

    54 TAV Legere; 61DS19 LHM BVH (son's); 71DS21 BVH; 73SM 3.0; 73SM EFI (Megasquirt); 73SM 3.0 (other son's)

  21. #21
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    Hi John,
    Many Thanks for the tip - I've filled the damper through the return line as best as I can with a small syringe. The corrector was full of fluid when I lifted one of the covers. I've refitted the original Citrotech corrector, and reset the link rod back to it's original position.
    I'll give it a go tomorrow with any luck with lots of low to high cycling and steering lock to lock.... fingers crossed...
    Cheers,
    Mark...

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    Quote Originally Posted by ds21bvh View Post
    Hi John,
    Many Thanks for the tip - I've filled the damper through the return line as best as I can with a small syringe. The corrector was full of fluid when I lifted one of the covers. I've refitted the original Citrotech corrector, and reset the link rod back to it's original position.
    I'll give it a go tomorrow with any luck with lots of low to high cycling and steering lock to lock.... fingers crossed...
    Cheers,
    Mark...
    Good luck Mark. David Bourne here in the UK (though I think he was based in France at the time?) solved his problem by driving round a farm yard several times - sounds like steering lock and bleeding air out of the system solved it.
    1968 DS21bvh Pallas in Gris Palladium

    Restoration blog: https://ds-restoration.blogspot.co.uk

  23. #23
    Fellow Frogger! ds21bvh's Avatar
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    Many thanks to everyone for their help and suggestions. I had another opportunity to play with it again and after some fiddling with the linkage all seems well again. I did as John suggested and primed the damper circuit which seems to have helped. I've never seen that problem before in all the time I've had Dees, but I've never fitted a new height corrector before....
    Kind regards
    Mark...

  24. #24
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    curious scenario Mark, I took front and back correctors off and cleaned out and new covers and put some LHM in the feed, pushed the valve back and forth and didn't have this issue. Good you sorted it.

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