What am I doing wrong?
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  1. #1
    Member HennovdM's Avatar
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    Icon5 What am I doing wrong?

    Earlier this week I got the DSpecial running again. (Last year October I had an overheating problem). On Wednesday I took it for Insurance inspection and I felt that the brakes was much to soft. Yesterday afternoon I bled the front and rear brakes. The front brakes while the car was at its lowest setting and the rear while on stands.
    I took it for a test drive directly afterwards and the brakes was 200% better, immediate response and the rear did not dip as much as previously. The only problem was that the suspension felt very hard. I immediately suspected a sphere but everything looked fine, no leaks.

    This morning I moved the car from one spot to another, checked the spheres (visually) there was no leaks. The LHM level was a bit low so again I suspected a diaphragm that popped.

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    My eldest son took the car for a visit around the corner just now and phoned me to inform me that LHM is leaking from the left front sphere. This is not the first time that this specific car has popped a LH front sphere, last year October was the same.

    Did I do something wrong during the bleeding process? Is there some sort of blockage in the return lines as previously I struggled to remove a sphere from the LH side as there was still pressure in the sphere?
    Or is it just poor quality diaphragms?

  2. #2
    VIP Sponsor richo's Avatar
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    You didn't mention if when the car is in the normal height positon if the left front side of the suspenson has smooth, soft movement up and down if you lift on the front of the bumper and release, or if you push down on the bumper with your foot and release.
    This is with the engine running or just stopped.
    A visual check of a sphere on the car is not usually a good indication of condition.

    When removing the front spheres, sometimes it is best to have the car on stands, put into low suspension position. Open the bleed valve on the regulator.

    If the sphere you want to remove is stiff in its mount...
    with a lever, move the road wheel up and down a few times, operating the suspension.
    There is a restrictor on the line, sometimes it becomes blocked. This helps relieve the pressure.

    When removing the front sphere you should always be able to "wiggle" the sphere, it shoud ALWAYS be free on its two pivot bolts.

    With regard to your sphere, it is possible, if the sphere is leaking around the equator of the two hemispheres, that the diaphragm is blown.

    Hope this helps.

  3. #3
    Member HennovdM's Avatar
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    Thanks Richo for the information. I'll test it tomorrow.

    What I did find out is that the O-ring on the extender leaked. I replaced it and now it is working but the ride is still hard. I'll update this post tomorrow.

    Henno

  4. #4
    Fellow Frogger! CorneSoutAfrica's Avatar
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    richo

    which line has got the restrictor in? I heared about this hydraulic line before, I know it is close to the front height corrector, which pipe got the restrictor in?

    Henno I will call you

    cheers
    Corne
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  5. #5
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    Quote Originally Posted by CorneSoutAfrica View Post
    richo

    which line has got the restrictor in? I heared about this hydraulic line before, I know it is close to the front height corrector, which pipe got the restrictor in?

    Henno I will call you

    cheers
    Corne
    Corne,

    In the fluid exhaust line that is attached to the front HC there is a flow control wire shoved into it during manufacture. That exhaust line then connects to a 3 way union with the other exhaust line from the rear HC and the line that takes the fluid from both back to the reservoir. Its purpose is slow down the flow of fluid from the front suspension when the HC is put in its lowest setting so the the car settles at about the same speed front and back. Over time the very small clearance between that wire and the inside of the line can get clogged with debris. It then prevents all pressure from exhausting out of the front suspension leaving anywhere from 5 to 100 or more psi in the front. This makes removing the front spheres nearly impossible.

    As Richo pointed out you should be able to 'wiggle' the front units when all pressure is gone. If you cannot it means either there is still residual pressure in the circuit or the locating screws for the front cylinders are to tight. If the latter they need to be set correctly.

    An easy way to relieve the pressure, if encountered, is put a floor jack under the front lift point and raise the LHS of the car allowing the wheel to drop. This will give the residual pressure somewhere to go as the suspension piston drops down. Once the pressure is relieved from the LHS the RHS should also come off easily.

    Steve

  6. #6
    Member HennovdM's Avatar
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    Steve,

    Before I start dismantling, which is the Exhaust line you're referring too? The "RETURN" or the "OVERFLOW RETURN" ? What is the best way to clean the debris in this pipe?

    (After I lifted the LHS of the car I can now remove the sphere without a problem and will test the pressure.)

    Thanks!

    Henno
    Attached Thumbnails Attached Thumbnails What am I doing wrong?-front-hc.jpg  

  7. #7
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    Quote Originally Posted by HennovdM View Post
    Steve,

    Before I start dismantling, which is the Exhaust line you're referring too? The "RETURN" or the "OVERFLOW RETURN" ? What is the best way to clean the debris in this pipe?

    (After I lifted the LHS of the car I can now remove the sphere without a problem and will test the pressure.)

    Thanks!

    Henno
    Henno,

    Looking at the HC as it is mounted to the car you will see two steel pipes attached to the top and one attached on the bottom.

    Pressure feed from the system is via the security valve or distribution block (depending on year) mounted on the firewall.

    The fluid return from the HC will be the other steel line attached to the top - this is the one with flow control wire inserted.

    Bottom - fluid that is sent to the suspension.

    The Nylon tube attached to the nipple screwed in to the top front is the leakage return to the reservoir.

    To clean. You need to remove that return line from the HC and where it connects to the union carrying fluid back from the rear HC. Then try blowing compressed air from the connection side (not from the union where it attaches to the HC). Fill the pipe with solvent (acetone, MEK, or the like) and then apply air under at least 90 to 100 psi to pipe end. Sometimes one will get lucky. However typically it requires hitting the pipe with high pressure fluid from the reverse side - something that requires a source of pressure and a way of applying it to the pipe all at once.

    Steve

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