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Technical Manual four wheel disc brakes

Discussion in 'The Hokey Ass Message Board' started by Doublepumper, Mar 1, 2019.

  1. Doublepumper
    Joined: Jun 26, 2016
    Posts: 597


    Hi everybody,
    I'm getting ready to finish up the brakes on my '46 Ford pickup and am looking for some input to keep me....or get me headed in the right direction. I have a disc brake kit on the front and have a 8.8 rear end with discs. The calipers on the front are the '78 - up GM metric type. I'm using the factory pedal setup with the M/C under the floor and going manual, with no booster. I'll be using a Parker proportioning valve and two pound residual valve for the rear, and two pound residual valve for the front. I'm planning to use a one inch bore GM Corvette style M/C, but I'm unsure if it will work OK for this. So far, I haven't been able to come up with any solid info for the proper M/C for this type of setup. Would really like to hear from anyone that has done this or can educate me.
    Thanks in advance!
    chryslerfan55 likes this.
  2. Frankie47
    Joined: Dec 20, 2008
    Posts: 1,727

    from omaha ne.

    I have entertained this thought myself......but then it is soooo easy to add a good vacuum canister and a boosted MC all hidden from sight.
    chryslerfan55 likes this.
  3. I’ve run that same brake set up on 2 different cars with no residual valves and it worked great. One had the master behind the dash and the other below the floor. Even under the floor, the master was still physically higher than the calipers, so I didn’t use residual valves.
    Frankie47 likes this.
  4. mgtstumpy
    Joined: Jul 20, 2006
    Posts: 7,977


    The booster just makes braking physically easier IMO.
    Frankie47 likes this.
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  5. oldiron 440
    Joined: Dec 12, 2018
    Posts: 1,506

    oldiron 440

    What you need is a 67 Corvette manual master, it ready to go with four wheel disks!
  6. Mike VV
    Joined: Sep 28, 2010
    Posts: 1,876

    Mike VV
    from SoCal

    Depending on your pedal length, pivot length, the one inch (1.00") piston should be fine without a booster.
    I have a similar setup on two cars...they are a two toe stop, no booster needed or wanted.
    The master cylinder brand doesn't matter, just the diameter and stroke. Most modern 1.00" cylinders have plenty of stroke.
    I used a Wilwood, dual, remote reservoir m. cylinder in both cars

    pitman likes this.
  7. rudestude
    Joined: Mar 23, 2016
    Posts: 2,435


    I did s 4 wheel disk brake set up on a 67 Camaro years's what I did rear was a Ford 9" with Lincoln disk brake assembly the front had reworked A-frames so I could use big GM spindles with 11" day that's small...and they had 4 piston calipers as for the master cylinder, I wanted non-power the car was going to be a street car but it was being built by scca trans-Am road race I wanted to be part of the car and feel what the car felt ...something I read once anyways..also the roll cage didn't give me any room for a was recommended that I get the master cylinder for a non-power 4 wheel disk brake big block Corrvette...and put a adjustable propositioning valve In the system when I went to order one it was a bit pricey then the guy asked if it was real important to have the Corvette cylinder ,they are made of aluminum with stainless sleeves and internals...cost was around $300 and they have the big wide large compasity reservoir...the guy then tells me he can order one for a 77 or so chevy 3/4 ton pu non power disk brake and it's the exact same thing as the Corvette one except its cast steel not aluminum everything else is the same both 1" bore....cost was $45 and no core charge...I bought it..the key is to have a smaller bore for non-power and power brakes bigger bore...and it all worked at the end...

    Sent from my SM-T387V using The H.A.M.B. mobile app
    Frankie47 likes this.
  8. Bonehead II
    Joined: Apr 18, 2005
    Posts: 391

    Bonehead II

    I have the same set up on my car..Had some problems, I changed the pedal to a 6.1 ratio and put a 15/16 bore master in. now she will stop on a dime....Good luck.
    Redrodguy likes this.
  9. Bob Labla
    Joined: Aug 15, 2012
    Posts: 68

    Bob Labla
    from mitten

    I used your same setup on my '40 truck. They work so good, I'm glad I didn't use a booster.
  10. Phil P
    Joined: Jan 1, 2018
    Posts: 267

    Phil P

    When you find a parts place with that "Guy" you put them on speed dial. Phil

    rudestude likes this.
  11. V8 Bob
    Joined: Feb 6, 2007
    Posts: 2,609

    V8 Bob

    As a general rule, 4-wheel discs need a power assist to provide comfortable braking, because of the higher pressures disc brakes require. I don't know of (or remember) any regular U.S. production vehicles, except some '60s Corvettes, that had manual 4-wheel discs, and I would not be surprised if the Vettes pedal ratio was 7:1 or higher.
    The problem with extreme (greater than about 6:1) pedal ratios is.....longer pedal travel. Hanging pedals can be easier to accommodate longer travel, but through-floor pedals not so much. So, as long as the master cylinder can be fully stroked before the pedal bottoms out, you're OK with a lower ratio that is normally needed for 4-wheel discs.
    Last edited: Mar 2, 2019
  12. missysdad1
    Joined: Dec 9, 2008
    Posts: 2,899


    I have a similar setup (GM metric calipers front, GM early style calipers rear) on my avitar hot rod using a 7/8" cast-iron 2-pot master cylinder (Pete & Jake's PN 1118-7/8) with 2-pound residual pressure valves front and rear and an adjustable rear pressure proportioning valve. I could not be happier with the stopping power and the pedal "feel" this setup provides.
    Last edited: Mar 2, 2019
  13. Doublepumper
    Joined: Jun 26, 2016
    Posts: 597


    I really appreciate you all for taking the time to help answer my questions. The collective knowledge here is amazing and I'm very glad to be associated with you all. I realize getting this system to work properly may take some juggling, but I sure would like to make it a once and done deal, as I've not done this before and working alone with limited resources, can't really afford to struggle too much with getting it right.
    I do have a master cylinder now that I'm planning on's this one from Speedy,4316.html?OriginalQuery=910-31445
    From the research I've done, I believe this will work, but I'm just not knowledgeable enough to trust myself in making the correct choice for my setup. Unless someone can explain why I shouldn't, I'll go with this M/C and hope for the best. Again, I can't tell you all how much I appreciate your help.
  14. pitman
    Joined: May 14, 2006
    Posts: 4,904

    from Hampsha

    Agree w/Mike VV, as I had no room for a booster. Correct dia. master cyl, and pedal length/leverage worked out just fine.
  15. Manual 4 wheel disk and even manual front only disk brakes never seem to have a good feel to them to me. A good manual, 4 wheel, self-energizing, drum brake system always feels more capable to me.

    As mentioned above, a smaller m/c bore and experimenting with the pedal ratio should make a noticeable improvement. And for a street driven vehicle you might want to avoid the harder, more aggressive pad materials. They don't work as well when they're cold. A lighter duty, standard pad should give you a better feel for normal stop-and-go driving.
  16. WB69
    Joined: Dec 7, 2008
    Posts: 1,188


    I've used the chevy truck MC, with the 2 lbs residual valves and adjustable proportioning valve with very good results. Getting the proportioning valve set right was a must that got rid of a soft pedal.
  17. anybody have a specific yr make model application for the 7/8 or 3/4 master bore with the driver side exit brake lines so that when reversed under the floor the lines will exit towards the center of the car? there was a Plymouth volare that was 4 wheel manual disc.... allegedly. I had one, and when it went out on the road,I replaced it with vette. 1" bore. couldn't be more unhappy with the hard pedal. still stops but old knees don't like it. and steering wheel is bent like a taco shell.
  18. There was no Volare that had four wheel disc brakes

    Sent from my iPhone using H.A.M.B.
  19. Binkman
    Joined: Nov 4, 2017
    Posts: 235


    I just went through this with two of my cars.
    I found a Raybestos 39037 worked for me 7/8 bore, lines point to the outside frame rail, and it was about 30 bucks on Amazon.
    One car was sitting for about 10years and the master was frozen and the other one was built with a Corvette 1 inch cylinder and it took too much pedal effort to stop the car.
    Matching master bore size to wheel cylinder bore size it critical, as well as pedal ratio.
    The 7/8 bore did the trick.

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