upgrade master brake cylinder

cruiser said

I'm thinking about converting my bone stock 1974 Duster with its original power front disc/rear drum brakes to the Mr. Diff aluminum and plastic MC referred to in this thread. How hard is this to do? Do the brake lines thread in correctly? Is there anything I need to do with the rod that comes out of the front of the vacuum booster? Thanks.

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It’s pretty easy. You’ll need the 4 bolt to 2 bolt adapter and a manual brake push rod (or an adjustable push rod from DoctorDiff). The power brake push rods won’t work with the manual master cylinder. The thread size on the lines should be the same, but they won’t be the right length/shape because of the change in location of the master cylinder after you delete the booster. Depending on their condition you may be able to bend them to make them line up. The factory lines don’t like to bend though, and if they’re even a little rusty they won’t handle the bending necessary to get them to line up with the manual master cylinder. For my money I’d replace the lines from the master to the combo valve, just order them now assuming the originals won’t bend without kinking or leaking. Otherwise you get the job half done, have a problem, and have to wait for parts or bend your own lines mid install.

DoctorDiff sells everything you need for the swap.