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Rear shock/nitrogen psi

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  • Rear shock/nitrogen psi

    My shocks were rebuilt and have the Schrader valve on the furthest aft set, on ones without springs. They do bottom out on bigger bumps, so thought I would try to add some nitrogen. Any idea of psi needed?
    Has anyone used the Classicgarage rear shocks with springs only? Think these are same or similar to T Rutlands versions?
    Suggestions requested.
    Last edited by johnak; 11-01-2020, 05:30 PM.

  • #2
    John Bishop knows for sure but I think it is about 300 psi. Well above what you can do with an air compressor or push-on inflation chuck. Who rebuilt your levelers and installed the Schrader valves, PSI, or Jeff LeBlond (I hope not), or? In my experience, anyone who does that is probably a hack and the rebuild never holds. Of the three different rebuilt units I've seen from three different shops, each one has made modifications to the internals because they can't source original seals. And none work afterwords. The only successful rebuilds have come from John, who had new original-style seals made. But he is sick and tired of rebuilding these monsters. if they are original then they are difficult to get apart and if they've already been apart they're always ruined inside.

    To fill them properly you need a "gasification" tool that bolts around the body of the shock. It has a connection for high pressure nitrogen and allows the removal/reinstallation of one of the grub screws while charging the shock and not releasing pressure. I have a homemade version of this tool, made by previous owner Aaron Masters years ago and used by John, but I'm not in a position to offer rebuilding or gasification services. I realize this doesn't actually help anyone but that's the current state as far as I am aware.

    There is a complete explanation of how these units operate on the library section of the site at If you look at the diagram there you will see that the location most rebuilders put the Schrader valve (on the body at the top of the diagram) does not provide access to the proper high pressure chamber.

    Click image for larger version

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    • #3
      Thanks. My shocks seem to be doing fine, rear is normal level so I think for now I will leave them alone, rides very smooth and only makes a noise if going very fast and hit a good bump, could be something else as ride is fine.
      Appreciate all your info.
      I did get an emergency window crank/brass gear from Australia, only thing my car did not have. Just changed oil form breakin oil, now has 4100 original miles, running great.