a couple of (dumb) brake line questions

[jocko]

So, I'm kinda working this upgrade to power brakes with a dual res master cylinder upgrade in the process (drum/drum) - with lots of help from the good Captain's parts shelf and an idea the ChiefRocka spawned in a thread he did about splitting the brake lines.

Couple questions coming up:

1. For a drum/drum arrangement - what is the proper size brake line for the front and rear reservoir - should they BOTH be 1/4" lines?

2. IF, big if, I decided to upgrade later to a disk/drum setup, I know I would have to replace the line to the rear reservoir with a larger line. What are the correct brake line sizes to the front and rear reservoir for a disk/drum setup?

3. Where does one get them thar fancy a-dapters that allow you to fit the correct size brake line to the master cylinder reservoir? (here's why I ask - I was looking at a 75 imp power disk/drum master cylinder - and a 5/16 line fit the front reservoir and NOTHING apparently fit the rear reservoir - 3/8 looked like the right size, but the fitting would not thread in. Now, I realize that these are too large and I need a reducer - but see question #2 for that... I'm just askin where I might find the adapters and wondering why even any wrong size in standard (even large) brake line sizes would not fit the rear reservoir - seems I'd have a problem finding an adapter that would fit also??)

4. For the current plan - I've got Captain's bracket, a 75 imp booster and a 67 C10 dual res master cylinder. What I am wondering is this - is there a difference between a master cylinder that was intended for use with power vs manual brakes? (When I looked up/ordered the 67 C10 master cylinder for this project, it did not differentiate a master for manual vs power brakes - but I've seen a few threads on here that seemed to imply that that there may be a difference. (But I don't think there is one)).

Thanks for your help - I am still leaning toward just upgrading to power booster with a 6y7 drum/drum master for now, but was considering grabbin a cheapie 75 imp disk/drum master to sit on the shelf if/when I ever do upgrade to disks up front. My assumption is that the drum/drum setup uses 1/4" brake lines all the way around and that a disk/drum uses 1/4" for the front reservoir and 5/16" for the rear - but I just don't know - thus the questions!

[protrash64]

I'm sure you can find the reducers at a well stocked parts store; I got mine at NAPA ages ago. They are also in the Speedway catalog if you prefer to order. Maybe Summit??

Is the rear line a 1/4'' where both the 5/16 and 3/8s dont work??

[jocko]

nope - on the plastic plugs that come in the mc ports, the front is labeled 1/2 and the rear is labeled 9/16. But I will need reducers to neck it down to the 1/4 brake line (and maybe 5/16" in the case of the disk setup - does anyone know the 2 brake line sizes that are used in a disk/drum setup, i.e. are they both the same size (1/4"?) or different between front/rear reservoirs?). Been doin a little surfing for brake line adapters, and it appears that it is normal to have a tube line fitting in between the mc and the brake line connection nut. I'm sure I'm not using the correct names for these parts - but there were many references to the "oem master cylinder adapter fittings" that allows the appropriate sized brake line to connect. For the drum/drum master cyl, I'm still gonna need a reducer/adapter or whatever to attach 1/4" brake lines front and rear on the mc.

Good call on NAPA, I'll probably stroll in there with the mc and see what I can find. Have to admit that it was a little frustrating at Oreily's - I drew the short straw and had an automotive parts counter expert lady lookin stuff up for me on her computer - that was less help than an answering machine. She knew even less than me, and that's scary. Then again, it's not my job. How I miss the old hometown auto parts store... Having said that, I'm pretty sure the teenager guy behind the counter wouldn't have been much better. I had to spell I-M-P-A-L-A for him.

[1964c-10]

FWIW,

i just redid my brake lines on my '64 and switched to power brakes and disk/drum. i ran all 3/16" lines to the front and rear brakes. from the little test driving i have done so far, everything seems to be working properly (on the brakes at least lol).

i got all my lines and fittings from my local Arnold's Motor Supply

[Captainfab]

The drum/drum system uses 1/4" front and rear, and the disc/drum uses 3/16" in the front and 1/4" in the rear.

[shortbed70]

My drum/drum 65 has 3/16 and 1/4. I got all my parts from napa. Reducers and line.
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[erock805]

you can use whatever line was in the truck to start with. And yes you will need the adapters from the master cylinder to the line. Got some at autozone last week for my 54 beliar.

To run discs you need the residual valve placed after the master cylinder and before the valve.

[jocko]

copy all gents, and thanks very much. There's some conflicting info in the posts above, but that's ok. Capt Fab - your answer is what I expected would be the textbook answer for both cases, makes sense based on the 2 mc's I've looked at and the different port sizes on the mc's themselves.

Here's what I'm going with:

1/4 front-1/4 rear for the drum/drum setup in the near term.
3/16 front-1/4 rear for disk/drum setup if I go that way in the future (and that makes sense when I look at the disk/drum master clylinder port size differences).

Shortbed 70 - your post gives me the most pause, I've never heard of a drum/drum setup with different size lines front vs rear. That's interesting - do you perhaps have a disk/drum master cylinder being used on your drum/drum setup? (only way to tell is the reservoir size - if the 2 res are the same size, it's a drum/drum mc, if they are noticeably different sizes, then it's a disk/drum mc). Just curious - your post was an interesting combo for drum/drum I thought. Would still work (as it obviously is for you) but might actuallyh be giving you a transparent/undetected brake bias - unless you're also running a prop valve to compensate??

Again, thanks everyone for posting, really appreciate it.

[krazy_texan]

On my 67 when I assembled it i left the 4 drums and pulled the mc and brake booster off of a 71 and bolted it up and never had a problem with the disc brake mc on the 4 drums so I know that can be done but I am fairly new to the 60-66s so I am not sure with the difference in mounting
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