Tech: Under floor master cylinder

Someone else was just talking about disc. conversions and under floor mounts, so I thought I'd post some pics and explain how I did it on my '54 Chev.
I'd checked several aftermarket outfits, but couldn't find a master cylinder mount for a manual trans. Yeah, I could've mounted a master cylinder and brake booster on the firewall and gotten a pedal assy. out of a newer car. But I like having the pedals come through the floor.
Using the old cylinder for measurements, and a new Corvette style 1" bore master, I came up with a design that would let me use the stock clutch and brake pedals and arms, and retain all of the stock linkage. I even incorporated the factory "t" block to hold the pedals in place.
My primary justification for this swap was to get a dual res. master under the floor. Yeah, the single bore worked fine, but, call it peace of mind.
At the time that I swapped things over, I had the floor pans cut out. So that made life a lot easier.
To actually build the mount, I used regular cold rolled steel. I used brass inserts in the pedal pivots. Nothing fancy, but it works well. I had to make some modifications to the bottom of the master, to keep the cylinder bore at the same height as the original. If the bore height had changed, it would have changed all of the pedal geometry.
The 'vette cylinder and the stock master have just about the same amount of travel to them (within 1/4"), so I had to make a new rod.
Once everything was installed, and I was sure that it was going to work, it was on to bending new brake lines. I ran the line from the reservoir (closest to the pedals) to the rear brakes, and the other to the fronts. Because the master sits backwards from it's traditional mounting, I won't confuse anyone by saying front and rear. I put a 10 psi RPV in the rear line, and a 2 psi RPV in the fronts. Once I got the brakes bled, and the floor pans welded in, everything seems to work fine.
I did have to cut a big hole in my new floor pan, to gain access to the master. So, I made a new cover from 20 gauge sheet metal, and mounted it with a piece of piano hinge. Done deal.

 

Very cool -- I'm going to hopefully have a similar type post on doing a dual master in the small BOP 61-63 cars (mine's a Buick Special Deluxe). I seen the scarebird.com site and he mentioned a '81 Ford Granada that might work . . . . so I've got a refurb on the bench right now. Great pics/tech. Thanks!

 

I had also looked at the Ford disc/ drum master cylinder. I went with the Corvette job because it fits under the floor pan. The Ford won't. I guess I should have mentioned that. You can get the 'vette master at any NAPA for about $32.00, so that's also a plus.