I am gettring ready to buy one of those dual bowl Mopar Performance master cylinders with the black plastic housing for my 70 Roadrunner that I converted to 4wheel disc brakes. Are they any good? I noticed that the smallest bore size for those is listed as 1.032 on the Mancini Performance web site. Wouldnt a smaller piston bore give a much more firm feel in the brake pedal?

hi
smaller bore gives more stoping power but also causes longer pedal movement .

i tryed 15 / 16 and had pedal go close to floor so wound up using the 1.031 .

66 belvedere with a hemi , manual disc / rear drum .

You can buy from local parts store, I got mine from Advanced Auto, lifetime warranty.
I'm using Diplomat application, manual brakes, 11.75 disc, with 11 drums.

This ^^^^ , the MP unit is the same as what was used on the production line .

I would contact DrDiff. Tell him what brakes you have and let him recommend the correct Master Cylinder size.
All depends on the size and number of the caliper pistons.

Agree. That's where I got mine.

Just to add, with 4 wheel disk, don't rule out fwd applications

Thanks for posting this. I definitely want a short pedal movement as my pedal movement right now is way too long.

Awesome information and reminder! However I will still need to purchase a adapter mount for the MP master cylinder because my power brake booster has the 4 stud mount and the current master cylinder having 4 holes like factory style for front disc/rear drum.

I always thought that a smaller bore MC would give less brake pedal travel but it seems everyone here says the larger bore MC would actually give less travel of the brake pedal which is exactly what I want.

If you have a power brake booster odds are good you will not need a M/C with a bore under 1".

Might want to look over this thread

https://board.moparts.org/ubbthread...ou-never-wanted-to-know.html#Post1235219

Thanks for posting this. I am going to give it a read right now.

Just as a reminder, those cheaper units at the parts store need to be modified if using a manual brake push rod (the ones under 1"). They don't have the slot for the retainer, and without the slot, the push rod can fall out and leave you without brakes. If you don't have the tools or know how to modify, like me, it is just easier to but the one that already has it done. If you do have that ability, then disregard.

As mentioned, call Dr Diff, he carries a couple different sizes and will help you decide. I have manual disc brakes so I went with 15/16", even with the 92 Viper front calipers. Also have 10.7 disc rear kit from the Doc.

I use windshield urerthane to hold the rods in without the groove. Once it sets up it's bonded for good/
Doug,