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Manual Brake Master Cylinder Help

Discussion in 'The Hokey Ass Message Board' started by pottsie454, Nov 23, 2011.

  1. pottsie454
    Joined: Feb 12, 2011
    Posts: 399

    pottsie454
    Member

    Well, I built a motor without taking in consideration for the powered brakes that I have currently installed and I am now forced to look at my options. Ive considered buying a electric vacuum pump but I am concerned on where to mount it and its reliability. So I am now looking into converting it to manual brakes. Now, this task doesnt seem to difficult if I had 4 wheel drums, but I do not. I have disc brakes up front and drums in rear. Can anyone suggest a master cylinder that will work for this setup? This is for my 53 chevy, nova front clip, and 79 8.5 camaro rear end.

    Thanks!
     
  2. JohnEvans
    Joined: Apr 13, 2008
    Posts: 4,883

    JohnEvans
    Member
    from Phoenix AZ

    Simple use the MC for non-power from the Nova. Be sure to change the pedal pivot point for the MC pushrod to the manual position.
     
  3. pottsie454
    Joined: Feb 12, 2011
    Posts: 399

    pottsie454
    Member

    That also is going to be tough.. because the whole brake assembly that I have is coming out of an S-10. So, do you think an S-10 manual brake master would produce the same effect? If you use a master cylinder originally used for 4 wheel drums how will that effect the front discs?

    Sorry, I am pretty new to everything, especially brakes... but I realize how important they are so I dont want to start piecing shit together and hope for the best.
     
  4. 39 All Ford
    Joined: Sep 15, 2008
    Posts: 1,531

    39 All Ford
    Member
    from Benton AR

    My son is running 4 wheel disk with his manual m/c, the right pivot point (as mentioned above) will help, as CAN a slightly smaller diameter m/c bore if the pedal is too hard.

    He is running a 7/8" bore on his OT car.
     

  5. Dapostman
    Joined: Apr 24, 2011
    Posts: 294

    Dapostman
    Member

    Why can't you use the booster? No port? No vacuum?
     
  6. pottsie454
    Joined: Feb 12, 2011
    Posts: 399

    pottsie454
    Member

    Large cam, lots of overlap.. no vacuum. The brakes are currently setup the way I bought the truck, with the exception of the front disc brakes, I put those on. But, the pedal assembly, booster, and master cylinder are all from a late 80s early 90s S-10.
     
    brimantz likes this.
  7. Dapostman
    Joined: Apr 24, 2011
    Posts: 294

    Dapostman
    Member

    Do you Know what size cylinders you have now? A twin bale Corvette style master from the 60s might work. You will need to use a smaller size cylinder than you have now. Your biggest problem will be that the pedal is most likely held on with the booster, and will have no provision to mount the mc, so it will have to be modified or replaced with an earlier unit.
     
  8. pottsie454
    Joined: Feb 12, 2011
    Posts: 399

    pottsie454
    Member

    Yeah, I am defiantly needing a dual master cylinder for sure. And Iam not apposed to making things work, I just want the right parts to begin with. 60s vette, I will look that up.

    Anyone know of an aftermarket company that might help me with some good tech support?
     
  9. Dapostman
    Joined: Apr 24, 2011
    Posts: 294

    Dapostman
    Member

    70s ford trucks had a manual disk drum, I can try and find some measurements tomorrow.
     
  10. amx180mph
    Joined: May 11, 2011
    Posts: 156

    amx180mph
    Member

    The bottom line is, if the stopping power of a car needs improvement, or if there’s a need to reduce the pedal effort, several options are available: (1) Decrease the master cylinder bore size; (2) Increase the pedal ratio; (3) Increase the wheel/caliper cylinder bore size. If the pedal ratio is increased, there will be more travel at the master cylinder piston. If the master cylinder bore size is decreased, the piston has to travel further to move the same amount of fluid. Typically, a master cylinder has approximately 1-1/2-inch to 1-3/4-inch of stroke (travel). The idea here is coordinate the pedal ratio with the bore size to arrive at approximately half of the stroke (roughly 1-inch) in order to make the brakes feel comfortable.
    Here is an excellent article that covers all the must know on brakes http://www.hotrodheaven.com/tech/brakes/
     
  11. maddog
    Joined: Sep 3, 2006
    Posts: 693

    maddog
    Member
    from So Cal

    You should have a 7:1 ratio on the brake arm for manual brakes. A friend of mine said he has used as much as a 13:1 ratio.
     
  12. sqhd
    Joined: Sep 9, 2006
    Posts: 71

    sqhd
    Member

    For non powered brakes with a disc/drum setup, use a m/c for a 1973-77 Malibu, as recomended by Scarebird for a conversion I'm doing right now.

    Carl
     
  13. V8 Bob
    Joined: Feb 6, 2007
    Posts: 2,737

    V8 Bob
    ALLIANCE MEMBER


    You definitely want to use a disc/drum or disc/disc master, not a drum/drum.
    Many vehicles had manual disc/drum brakes through the late 70s, and the most common master cylinder size was 1". Smaller bores will result in lower pedal efforts but with longer strokes for a given pressure, and just the opposite for larger bores. Just make sure the master you use can be fully stroked before the pedal bottoms out!
    There is no difference between a manual and power master, other than a deeper push rod bore on most power master primary pistons, which makes them a better/safer choice for manual custom builds, as the deeper bore retains the push rod better on a custom setup.
    Manual pedal ratios are usually 6-7:1 to keep pedal travel reasonable, but have to allow full master travel.
     
  14. budd
    Joined: Oct 31, 2006
    Posts: 3,478

    budd
    Member

    i would look at just trying your master you have now, just remove the boster and bolt up the master, might need a little adapter made but keep it simple till you see how it's going to work, just to try, might work fine.
     
  15. Mitchell Rish
    Joined: Jun 10, 2007
    Posts: 1,176

    Mitchell Rish
    Member
    from Houston MS

    I just converted my 51 chevy truck to 4 wheel disc and used a 69 vette master cylinder for manual disc brakes - The L88s etc, all had very big cams for the day. Mine will stop on a dime . I used the proportioning valve form speed way along with the residual valves both front and back. I repeat Will Stop On A Dime.
    Mitch
     
  16. pottsie454
    Joined: Feb 12, 2011
    Posts: 399

    pottsie454
    Member

    Will a 69 vette master work with only front wheel disk? Maybe that and a proportioning valve. What does residual valves do? Never heard of them.
     
  17. Gerry Moe
    Joined: Jan 29, 2006
    Posts: 498

    Gerry Moe
    Member

  18. electromet
    Joined: Mar 19, 2011
    Posts: 151

    electromet
    Member
    from Tucson, AZ

    If the major issue is the lack of vaccuum, why not use an engine-mounted mechanical vaccuum booster? I had a '69 AMX that had vaccuum wipers, and AMC used a vaccuum pump piggyback-mounted on the stock mechanical fuel pump to provide adequate vacuum while under acceleration. Worked just fine.

    Residual pressure valves are in-line hydraulic devices used on vehicles with under-floor master cylinders. The valve prevents the brake fluid from draining back from the wheel cylinders/calipers to the master cylinder. Otherwise your pedal stroke would be exceptionally long.

    Mike
     
    Last edited: Nov 24, 2011
  19. budd
    Joined: Oct 31, 2006
    Posts: 3,478

    budd
    Member

    i have a 75 chevy pickup that came with disks front and drums rear, non -power, one of the main differences between a disk and drum master is the size or the fluid reservoir, think about it, a 2.5" piston will move about 1" per wheel from the time the two pads are new till their down to metal, so you need 4.9 CI of fluid per side or 9.8 CI total fluid in the master so it doesnt run out of fluid, hence you see masters with a large and small reservoir, dual disks have two large, then later on they just used the large one on everything just to make it simple it would seem.
     
  20. mrforddude
    Joined: May 30, 2010
    Posts: 134

    mrforddude
    Member

    I'm pretty sure those old crapbox S-10's had manual M/C's on them...stay with what you already have set up...no sense in re-inventing the wheel (or how to stop it in this case)
     
  21. Butch11443
    Joined: Mar 26, 2003
    Posts: 353

    Butch11443
    Member

    If you got power steering on that 53, use a hydro booster for it.
    Butch
     
  22. cruizznn
    Joined: Feb 18, 2009
    Posts: 168

    cruizznn
    Member
    from ohio

    I found this older thread and thought I might ask something on the master cylinder issues. I am setting up a willys coupe with manual brakes. All I have read everywhere, it seems like I would like to stay with 1" bore size. I am running 11" speedway disc kit with metric calipers on the front and 11" rear drums on a 9" ford rear. My pedal ratio is around 6-1. At this time I will try to make either side work for brake lines but would rather have them on the right. I had a 34 ford years back that used a nice compact (what i thought was a ford master cylinder)so I did a lot of looking to find something that seemed to use these brake sizes. I bought a raybestos 36399 cylinder which in the pictures had the same look as what was on that 34, however when I got the thing it is really big! I can't mount that big cow under the car where I need to go. I know for a fact that old cylinder on the 34 was smaller, had the same look, and now I am not sure what it was, but it did have the bigger size resevoir for disc. So my question is...does anyone have an application or any part numbers that would be manual brakes, 1" bore, small size, disc/drum resevoir, and preferably lines on the right towards the engine? I find a raybestos 36440 for a 76 maverick, must II, and granada, but is a 15/16". I have read the facts about bore size and how it affects the pedal travel and feel. thanks... master.jpg
     
  23. Mike51Merc
    Joined: Dec 5, 2008
    Posts: 3,855

    Mike51Merc
    Member

    Of course this is an old thread, but for guys in a similar situation--- modern (early-mid 2000s) Volvos have a neat little electric vacuum pump that has a built in pressure sensitive switch. This pump, combined with a storage canister, would make a simple inexpensive solution for this problem.
     
  24. pottsie454
    Joined: Feb 12, 2011
    Posts: 399

    pottsie454
    Member

    Good call Mike... I looked that up and I will have to keep it in mind. I dont think it was ever stated on here but I ended up getting a tri-cylinder setup from wilwood for my application. It was a lot more money than I wanted to spend but when you need to stop... pinching pennys isnt worth it. ;)
     
  25. sunbeam
    Joined: Oct 22, 2010
    Posts: 5,128

    sunbeam
    Member

    You might try a vacuum canister. It must be used with a check valve. You may have low idle vacuum but vacuum under deceleration will still be pretty good.
     

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