Marzocchi top cap

[Garry]

Hello all, I am restoring my (originally from England, then move to Germany and now happy in the Netherlands) RGS and am currently working on the Marzocchi front fork, among other things.
I can see a screw, a spring with rubber and a very small hole in the top cap.
What is the function of this construction? I cannot find it in the parts book or workshop manual.
Regards Garry

 

[wdietz186]

It is a vent to prevent pressure buildup in the tube when the oil/fork heats up in use. One way [sort of] valve to let pressure out and not suck air in.

 

[Garry]

But does that screw seal it again, or can air still escape through it?

 

[wdietz186]

The screw allows air to pass, not a lot but enough. You don't need to crank it down hard.

 

[Garry]

Okay, thank you for the explanation. Learned something new again.

 

[Gazman]

I wondered what that was for