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Technical master cylinders

Discussion in 'The Hokey Ass Message Board' started by flatheadgary, Oct 14, 2021.

  1. flatheadgary
    Joined: Jul 17, 2007
    Posts: 878

    flatheadgary
    Member
    from boron,ca

    what is the difference between a manual one and a power one? can you put a manual onto a power canister?
     
  2. fastcar1953
    Joined: Oct 23, 2009
    Posts: 2,625

    fastcar1953
    Member

    Simple answer is no. They have different push rod lengths . May have different bore sizes.
     
    jimmy six and egads like this.
  3. Torana68
    Joined: Jan 28, 2008
    Posts: 1,280

    Torana68
    Member
    from Australia

    if you need a 1" and its a 1" and the mounting is the same, yes.
     
    2OLD2FAST likes this.
  4. egads
    Joined: Aug 23, 2011
    Posts: 1,110

    egads
    ALLIANCE MEMBER

    @fastcar1953 Is right. Power master usually has a shallow pushrod hole, the manual usually has a deep pushrod hole.
     
    pprather likes this.

  5. A master cylinder is a master cylinder. The differences are in the design/construction not that one type is for a power booster and another one not.

    Pushrod difference? Nothing that can't be altered to work. In this craft, the concerns are more along the bore size, mentioned, and brake pedal pushrod ratio.
     
  6. egads
    Joined: Aug 23, 2011
    Posts: 1,110

    egads
    ALLIANCE MEMBER

    Power master-- 71VjM-1fn0L._AC_SL1500_.jpg manual master-- 91031445_L850_198428da-86ba-49e0-bb2c-c2e6867f97d1.jpg
     
    Hamtown Al likes this.
  7. THE FRENCHTOWN FLYER
    Joined: Jun 6, 2007
    Posts: 3,800

    THE FRENCHTOWN FLYER
    Member
    from FRENCHTOWN

    I hope you're right. Somebody gave me this new MC for my replica champ car. I am not using a booster.

    brake 11.JPG
    brake 14.JPG

    Does anybody know where I can buy the rubber dust bootie that fits on the end of the bore? It will be very useful on a dirt track.
     
  8. squirrel
    Joined: Sep 23, 2004
    Posts: 49,825

    squirrel
    Member

    You probably don't want to use a booster type MC with manual brakes. Think about what happens with the pushrod, when something goes wonky, and it falls out, or gets wedged into the wrong place....

    Some later manual cylinders have the push rod retained in the piston, to prevent this type of problem.
     
  9. egads
    Joined: Aug 23, 2011
    Posts: 1,110

    egads
    ALLIANCE MEMBER

    How far does the rod go into the master cylinder piston? Dorman might have a boot?
     
    Last edited: Oct 16, 2021
  10. I'm running a power/booster type master on my 51' with manual brakes front and back, have been for over 20 years. Absolutely no issues!
     
  11. 1971BB427
    Joined: Mar 6, 2010
    Posts: 7,045

    1971BB427
    Member
    from Oregon

    The real difference is in pedal ratio. Most GM cars built back when there were cars sold with manual or power brakes had pedals with two hole locations in the arm. You put the pushrod into the hole closest to the pivot point for manual master, and furthest away for power.
    When I converted my OT Chevy to power brakes I used the same master, and simply mounted the booster behind it, and moved the pushrod to the lower hole. Worked perfectly fine.
     
  12. jimmy six
    Joined: Mar 21, 2006
    Posts: 9,996

    jimmy six
    ALLIANCE MEMBER

    Vacuum booster MC’s are usually 1” or 1-1/8”; manual are 7/8” and can be as low as 3/4”. Manual work best with 6 or 7 to 1 ratio but are fine with 5 to 1. A vacuum booster system with a 7/8” MC and a 6 to 1 pedal ratio will be very sensitive especially in a light vehicle and may put you thru the windshield.

    If using drum rears on a non booster system and the rear end is from a booster system vehicle you should change the wheel cylinders to a smaller size to be compatible.

    Auto manufacturer engineers design systems for specific use. We are the ones that mix and match incompatible parts at times.
     
    ClayMart likes this.
  13. 55blacktie
    Joined: Aug 21, 2020
    Posts: 452

    55blacktie

    As mentioned, the pedal should be adjustable. Rod length could be an issue, but you can shorten it if it's too long; get a longer one if it's too short. Wilwood has a good selection of rods. However, power brakes usually use a mc/w a larger bore diameter. I have manual brakes on my 55 Tbird-discs up front/drums rear. 15/16th bore was recommended; OEM is 1-inch. By the way, I also have Wilwood's proportioning valve.
     
    jimmy six likes this.
  14. I always think of Master Cylinder, a baddie on Felix the Cat
    [​IMG]
     
    egads likes this.
  15. flatheadgary
    Joined: Jul 17, 2007
    Posts: 878

    flatheadgary
    Member
    from boron,ca

    thanks for all the replies. as far as the rod length goes. if i can build a whole car i can surely make a new rod.
     
  16. enjenjo
    Joined: Mar 2, 2001
    Posts: 2,548

    enjenjo
    Member
    from swanton oh

    If you want to use the power master cylinder on a manual system, pull the piston out, and drill the the pushrod end of it deeper so there is no chance the pushrod can fall out. you can go a half inch or so with no problems.
     
    pprather likes this.
  17. THE FRENCHTOWN FLYER
    Joined: Jun 6, 2007
    Posts: 3,800

    THE FRENCHTOWN FLYER
    Member
    from FRENCHTOWN

    The rod goes in about 2 inches. The piston has a stroke of 1.05".
    Thanks for the Dorman suggestion egads. I'll check out their offerings after I measure the OD groove..
     
    egads likes this.
  18. jimmy six
    Joined: Mar 21, 2006
    Posts: 9,996

    jimmy six
    ALLIANCE MEMBER

    I don’t know what you are working on but I bought an adjustable rod from Summit for a Mustang on the recommendation for the disc brake kit supplier. It made my installation easier. I also could have made my own.
     
    Last edited: Oct 17, 2021
  19. Torana68
    Joined: Jan 28, 2008
    Posts: 1,280

    Torana68
    Member
    from Australia

    Your significant other knows brakes , just ask, they will say its the size that matters.
     
  20. They make these to turn a manual into a power MC. 21itzM4X75L._AC_.jpg
     
    egads likes this.

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