Vacuum Brakes, gaskets?

[tomjon]

I have started the vacuum brake conversion. After removing the Powermaster unit there remains a rubber seal bonded to the firewall. Should this be removed before installing the vacuum boost unit? Is it supposed to be mounted metal to metal? Is there supposed to be a gasket between the vacuum boost unit and the mastercylinder? And, does anyone know the thread size on the studs that the mastercylinder attaches, metric or standard?
Thanks

 

[Red Regal T]

Yes, remove the thick powermaster gasket. There is a paper thin gasket that is original between booster and firewall. You could cut one from gasket paper because it's probably not available. And the threads are metric. The nuts that retain the powermaster are the same.

 

[tomjon]

Thanks, and is there a gasket between the master cylinder and the booster?

 

[Red Regal T]

No.

 

[HyperV6]

You can get the gasket that goes between the booster and the firewall from a GM dealer. I bought one about a year ago and it costs about $7. Have the dealer look it up - just say for a non-turbo V6 car.

Craig