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Technical Master cylinder bore size vs booster size

Discussion in 'The Hokey Ass Message Board' started by 46fatford, Aug 4, 2019.

  1. I'm in the process of finishing the build on my dad's 41 ford tudor. It currently has mustang II rotors and calipers on the front and a mercury mountaineer rear with discs. The rotors/calipers are not big by any stretch. Anyway my dad bought a 9" corvette booster and corvette master for 4 wheel discs. I don't like the look of that huge booster and am not sure the corvette 1" bore might be too much for the calipers. I'm thinking 7/8' bore master and 7 single or dual diaphragm booster. looks much better too. I know the suspension is O/T, but was hoping for some advice. Is there any real advantage/disadvantage on single vs dual diaphragm boosters? The car is being built in an early 60's style with sears mags up front, chrome reverse out back, dumps with caps, nerf bar bumpers, roll and pleat, early 60's t bird buckets, metal flake steering wheel etc. Probably won't display with hood open. Its just a built up 302 ford anyway, nothing special. I'm also adding a line lock and wilwood adjustable proportioning valve. My dad did all the suspension and drivetrain, before I got it from him. I already bought a nice heavy duty pedal assembly, similar to the old Ansen style pedals too.
     
  2. squirrel
    Joined: Sep 23, 2004
    Posts: 55,944

    squirrel
    Member

    I'd suggest you try it first. If you decide the booster is too damn ugly, try a 1" bore m/c with no booster at all, and see how it stops. It might be fine, it might not, there are a lot of variables. Make sure the pedal ratio is sufficient, and that it also can make the master cylinder move to the end of it's travel.
     
  3. 6sally6
    Joined: Feb 16, 2014
    Posts: 2,459

    6sally6
    Member

    With no more weight than you are trying to stop.....manual discs will stop it EZ! (front disc/rear drum....a Maverick M/C woulda worked)
    'Don't need no-stink'in-booster' If the little 302 is gonna be "cammed-up" like a hot-rod-41-Ford should be!! you sure won't need a boosted brake set-up!
    See.........I just solved ALL your brake issues for you.:)
    6sally6
     
  4. Thanks for the advice. My dad set it all up with the 4 wheel discs. I would have been fine with rear drums. As for the engine, yes it's cammed up, very little vacuum signal. 224 degress duration at .050, .542 lift, 107 center intake, 117 exhaust.
     

  5. jimmy six
    Joined: Mar 21, 2006
    Posts: 14,802

    jimmy six
    ALLIANCE MEMBER

    I just installed front discs without power to my 56. It already had a revised rear end with 11" F-150 drums. One of the most important things is the mechanical advantage you gain in the pedal ratio. 1 to 5 will have less than 1 to 6 and so on. Mine was 1 to 5 and the MC is 7/8" by recommendation of Wilwood works perfect and feels waaay better than 4 drums and I would say real close to power assist.
    Your normal disc brake front caliper is a single piston floater style. This also needs to be considered. I bought a 4 piston no floater design with an adjustable rear proportioning valve built in to the prop valve. For my system a 10# residual valve was also needed.
    Brake systems need to be thought through and not just thrown together from E-Bay on the cheap. There are very good brake companies out there. doing them correctly. Take the time to call an check with their tech.. Believe me you can tell a guy who knows what he is talking about and a salesman..Good Luck.
     
  6. 55styleliner
    Joined: May 11, 2015
    Posts: 563

    55styleliner
    Member

    My ‘36 3 Window was way over boosted and difficult to modulate with a 7” dual diaphragm booster and 1” bore. I switched it to to a 7” single diaphragm and a 1-1/8” bore master but couldn’t lock them up without excessive pedal pressure. Went back to a 1” master on the 7” Single diaphragm and it’s perfect. I have a stockish 350 with Mustang II rotors up front and 8” rear with drums. It’s mounted under the floor and I didn’t check pedal ratio, because I couldn’t change it without much work. But it appears to be more appropriate for manual brakes. But I am very happy with the cars brakes now.
     
  7. I'm not sure of my pedal ratio, how do I determine that? I bought the pedal assembly from Southern rods last year at Ducktail run. The 7" booster is universal from Speedway motors. My pedal assembly looks just like the ones offered by Speedway, perhaps they know the pedal ratio. Sounds like I may have the right combo already with a 1" bore master and 7" single booster. I'll check on the pedal ratio. Thanks to everyone for the advice. I've never installed a complete new system on a project. My 46 ford was original brakes with 53 F100 in front, and both of my 56 Oldsmobile's were stock power drums.
     
  8. 55styleliner
    Joined: May 11, 2015
    Posts: 563

    55styleliner
    Member

  9. Kan Kustom
    Joined: Jul 20, 2009
    Posts: 2,739

    Kan Kustom
    Member

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