Gasket Material critical? - master cylinder to brake booster

[greeney]

Is Gasket Material critical for master cylinder to brake booster? I notice the old one is paper thin and the one I cut from a roll I got at Autozone is thicker and a soft material. Not sure if this gasket is there more to stop vacuum leak or brake fluid leak.

 

[Bad Luck]

That gasket is for vacuum leaks. You do need a gasket there.

 

[MaineRunna]

I don't think the gasket seals vacuum, and it definitely does not seal brake fluid. I think it is just to keep moisture out.

 

[HiLife]

^^^
You beat me too it.
My thoughts extactly.