Replacing the rear hydrospheres

First, all 4 wheels need to be off the ground, when the hydraulic pressure is lost, the car drops to the ground. First of all this is for safety, but second also because there will be a lot of fluid, if all wheels are off the ground most of the fluid are in the “shocks” and you will not have as much to get into a bucket.

The rear ones a located in the spare wheel compartment, but all connectors are under the car. Start with spraying all the bolts and nuts with some oil or whatever lubricant/rust desolver you have. We will start with the rear ones, passenger side (right) is easy:

Usually you will damage the pipe connectors very much since they are soft, I try first to loosen them, if not easy I make a cut with a Dremel over the thread of the sphere to make the thread “larger”. The spheres are never going to be used anyway. Trust me, you will otherwise damage the pipes.

Then there is the bleeding, while you wait for it to stop, losen the Three nuts that holds the sphere in place. Then you can start removing the rear silencer, getting access to the rear drivers side (left) without doing this is possible, but I wouldn’t do it.

Here is the left one with the cut I made to be able to remove the connector without causing to much damage:

Once all the nuts are gone, get the spare wheel out and you can easily remove the spheres:

New spheres in place:

And everything mounted, I sprayed it with some bodyspray just to make the connector easy to remove next time:

4 thoughts on “Replacing the rear hydrospheres

  1. Did you replace the dampers ( shocks)? Is this the first step to evaluation the R 129 “self leveling” suspension?
    I think time has lessened the sphere’s effectiveness. I assume that may also be the same result for the hydraulic shocks, and maybe the ADS valve.
    Is the entire replacement of the valve, four spheres and shocks needed to have the designed ride?

    • No, I did not replace the dampers. This is a hydraulic system, it will not go bad, either it will work or leak. The dampers will not fade, unless they are leaking. Same with the spheres, it is not the rubber membrane in them that is the suspension, it is the fluid pressing against the gas on the other side. The membrane is just there to separate them.
      I would replace the seals in the valve as soon as possible and leave the others things for when they break. But that is me, I have learned the symptoms. I have never had a leaking damper yet, the spheres tend to keep for 100 000 km or 15 years, the seals seem to be 15 years.

      Thank you for reading…

  2. Hi Gus,
    How do I know if only one sphere is bad? Or should I just change all 4?

    Thanks for all the great information!

    • You don’t, you replace them all they have a limited life seem to be 10000-150000 km. But you should be able to feel by pushing on each corner if the car, the stiff one is the broken one. Strongly recommend doing them all though, not so expensive if you do it yourself.

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