master cylindeer replacement

[1948F-1Pickup]

No data. My front setup is basically 65/67 Mustang disc and the rear is stock drum, so my 67/68 Mustang master isn't straying far from its original design parameters.
In general a single reservoir master uses maybe a 1" stroke and the Mustang unit I believe is a hair over 1.5" stroke. Original truck MC bore was 1 1/16" or
so. It would have been a pretty short pedal stroke if the shoes were pretty
close to the drums.

 

[V8 Bob]

Mainly was interested in an data you might have on how well your dual system might work in a failure situation. It's very difficult to design these systems to work in older vehicles and any actual data would be good. I have a system I should be able to test in the future.

It's really not difficult on older vehicles, as long as the master cylinder can fully stroke before bottoming out on the floor, and the same holds true for later modern vehicles.
The front brakes in the older and common vertical front/rear split system will usually stop the vehicle a little longer in distance than full system, while rears-only will take about twice the distance, but still much better than no brakes at all! All vehicles since '67 have to pass D.O.T. brake performance stopping distance requirements with full and partial systems, something I've performed hundreds of times. Lincoln/Bendix duo-servo rear drums are going to perform a lot better than the marginal Lockheed non servos that so many covet.
I'm not going to promote dual masters, duo-servo drums, front discs etc because I'm biased, having tested brakes most of my adult life, but I don't think it's good to discourage someone who wants to upgrade to a safer better brake system, especially in this day and age, IMO.

 

[glennpm]

Yes Bob, it's all abut the stroke

The early Ford, floor mounted setups have limited stroke. As with all installation, the brake shoes should be adjusted well and limit the take-up gap for the master cylinder push rod.

Glenn