Front drum to disc master cyl conversion

The edge of the rubber liner needs to be squeaky clean from particles of any kind to seal well. Take the rubber liner our and clean it thoroughly; often rust particles will get on that aedge and it will not seal.

Other than that, the edges maybe rusted and pitted. Is this MC new or used?

Is this the bolt on type of MC cover, or the type with the bail clip that flips up over the top? Where is the leakage: all around or in 1 or 2 spots? Does the liner have the concentric rings of collapsing rubber in each compartment? Make sure these are collpased and nested in each other to make the liner flat when it goes in the cover.

And 'yes' on the squirting all over he** and creation as normal....!