Curious Question on Master Cylinder for Disc Brake Conversion

[maginter]

So, still being new to the FFR world, the recent threads on rear brake conversations has got me curious.

The conscious is to use the 15/16" bore from a 94-96 Mustang with the FFR #16285 - Performance 11.65" Rear Brake Set and I am good with that. However, if you look at the MCs that are shown as replacements for the Ford Factory 11.65" rear rotor is a 1.063 or 1-1/16" bore. I get that there is basically a 6% difference in volume can yield lower pressure at the caliper......

So, my question is, does using the 15/16" bore just give better pedal feel or improved brake performance with the FFR Cobra?

TIA,

Mark

[CraigS]

Using the smaller size MC gives more hydraulic advantage so, for any given amount of decel, you will need less pedal pressure. I am pretty sure that all the parts applications you are referencing have vacuum boosters. So a larger MC works because you have help activating the brakes.

[maginter]

Using the smaller size MC gives more hydraulic advantage so, for any given amount of decel, you will need less pedal pressure. I am pretty sure that all the parts applications you are referencing have vacuum boosters. So a larger MC works because you have help activating the brakes.

OK, so the 15/16' MC is based on a Manual braking system and with Power brakes it is so marginal, it is a don't care... Am I making a correct assumption?

[Jeff Kleiner]

I have used the 15/16” master on several power brake builds.

Jeff

[Norm B]

Ford used different master cylinder bore sizes for different caliper types. Single piston calipers on the base model Mustang used a 1 1/16 bore. The dual piston front calipers and bigger brakes on the Cobra models got a 15/16 master cylinder. Try to use the master cylinder for the calipers you have.
Note the 15/16 bore master cylinders were set up to provide more front brake bias due to the higher front/rear weight distribution of the V8 engined cars.

HTH
Norm

[maginter]

Thanks Jeff and Norm for the explanation. Again, this was a curious question and I assumed it would be something based on the pressure and volume as to which one would be used. I am just trying to learn more about these cars and their setups.... I have the 15/16 bore master cylinder that I will use with the power brake setup I am going to install. I just need to get the brake kit from FR and I can start.

Thanks again!

Mark