AD Brakes from scratch?

Discussion in '1947-1954' started by Root2812, Feb 14, 2015.

  1. Root2812

    Root2812 Member

    Joined:
    Oct 19, 2011
    Messages:
    195
    Location:
    Coon Rapids, Mn
    So I am running into some trouble planning my brake system because I just don't know what I need. I am starting with nothing on a bare stock frame and have disk brakes front and back. I want to stick with the frame mounted master cylinder but don't know what I need.

    I've found two masters on the web and one says I need proportioning valves and 2lbs residual valves. Honestly, I've only done the brakes at the wheels and have no idea what things go into the system or if I need anything special since the master is at wheel level and not up high on the fire wall. If you guys could help me out that would be awesome.

    Also, anyone have experience with either of these masters? One is from the host and the other is a bit cheaper. I am curious about the power part too. These say they are poser masters but is that vacuum boosted or electric. I wasn't sure if a vacuum line would be run way down there.

    http://www.fabquest.com/search-by-t...vy-pu-truck-power-brake-pedal-assemblyly.html

    http://www.classicparts.com/1947-54...on-Disc_Disc/productinfo/71-905/#.VN9fjrk5CM8
     
    Last edited: Feb 14, 2015
  2. 50 Chevy LS3

    50 Chevy LS3 Member

    Joined:
    Jan 14, 2013
    Messages:
    951
    Location:
    Indiana
    Greg, I think you will need 2lbs residual valves, both ways with four wheel disc brakes.
    Ol' Chebby is the guy to show and tell.
    On the power brake/ master cylinder subject, I have almost the same set-up as you. I've about decided on manual brakes, 7/8" bore Wilwood MC.
    That seems to be what Art Morrison is using on his stuff.
    You have to be careful about MC bore size, well, everything when it comes to brakes.
    I'm sure one of the experts here can set you straight.
    Been missing your build updates.
     
    Last edited: Feb 14, 2015
  3. Root2812

    Root2812 Member

    Joined:
    Oct 19, 2011
    Messages:
    195
    Location:
    Coon Rapids, Mn
    Thanks Steve. My updates have been few and far between because progress has been at almost a halt. My so called good motor turned out to be no good and my dad was going to have a tech at his auto repair shop rebuild it for me. Unfortunately the tech (who is also my uncle) had a stroke and now the motor is just sitting there. I may take a stab at it myself and see what happens. I also had a baby 6 months ago so I haven't had as much time to go up and work on the truck since it isn't at home right now, plus we had birth complications and it got very expensive after the insurance ran out. Don't worry, everyone is ok and my daughter is perfect.

    I have finished the suspension mods and got the frame painted. I just need to finish bolting the front suspension back on since I took it off for paint. Then I plan to tow the bare chassis home and start on the brake system and the fuel system after my motor is rebuilt. Its just been a lot of road blocks but things are looking up. The 2015 goal is to have the brakes, fuel and cooling systems done so I can go fire the motor even without the body. Body work will start at some point.

    As for the brakes, I don't know if I want power brakes or not. That's just what I have been seeing for disk/disk set ups. I think manual brakes should do the job just fine even if I have 300hp. I didn't know anything about the bore either. Good thing I am asking. Brakes are the most important part of the truck after all.
     
  4. coilover

    coilover Member

    Joined:
    Mar 30, 2005
    Messages:
    2,564
    Location:
    Plano US
    With disc use all 3/16 steel tubing. One rubber hose for each front caliper and one rubber hose with a 3/16 inverted flare "T" mounted on the rear end. One three way 3/16 "T" mounted near the left front rubber hose. After everything is mounted measure from master cylinder through a 2# residual pressure valve to front T and master cylinder through a 2# RP valve and an adjustable proportioning valve to rear rubber hose. Buy lines the correct length and install allowing enough length to clamp to frame in several places. Measure from front T to left front rubber hose and from T to right front rubber hose; buy correct length steel tube and install. Measure from T on rear rubber hose to the right and left caliper, buy steel tubing and install. If under the floor master cylinder reverse bleed and your done. If firewall mounted MC bleed in the conventional manner. Notice I said to buy tubing the right length unless you have a grand to get a GOOD hydraulic flaring tool that gives leak free flares the FIRST time. I have a 2 grand pile of flaring tools under my bench that include an Imperial that works on old tubing but not the cheap new stuff, a Fedhill (junk), an Eastwood Fedhill clone (junk), and several I'd have to get the names from. With 3/16 you can hand bend and do a decent looking job or buy one of those triple size tubing benders and make your bends look real pretty. Good luck.
     
  5. Root2812

    Root2812 Member

    Joined:
    Oct 19, 2011
    Messages:
    195
    Location:
    Coon Rapids, Mn
    Can you describe reverse bleed? And if I read you right, going rear I should have the master cylinder then line then 2# RP valve then more line then adjustable prop valve? Any requirements on length of line between valves? No prop valve up front?

    That seems simple enough. Any good sources for those parts?

    I still need to decide power vs manual MC.
     
  6. coilover

    coilover Member

    Joined:
    Mar 30, 2005
    Messages:
    2,564
    Location:
    Plano US
    Reverse bleeding is where you force the fluid, under pressure, through the bleeder screw on the caliper back to the master cylinder. It works better when the master cylinder is mounted lower than the calipers. Actually the proportioning valve should be mounted first in the rear brake line then the residual pressure valve. You only need one proportioning valve to cut the pressure down to the rear brakes since trucks especially are light in the rear and will lock up the rear brakes if receiving the same pressure as the front brakes. Sometimes with large rear tires and smaller rotors and pads on the rear one can get by without a proportioning valve but you sure don't need the rears locking up on a slippery road so a PV is a good idea.
     

Share This Page