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Thread: master cylinder

  1. #1
    Grammarian no, Rider yes ISAMEMON's Avatar
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    master cylinder

    so , with fittings
    can a master cylinder for a single disc work great for a dual disc
    I was thinking I could come out of the master with a "t" fitting
    or is it a different bore and more juice
    ( thinking about converting to dual disc and cant find a used dual master)

  2. #2
    Liaison 20774's Avatar
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    I can never remember which way this goes, but I think you're going to have problems with the amount of fluid travel in order to push two pistons. The hand lever motion won't be the same. I think the thing to do is to go down a mm or two on the diameter of the M/C piston. I'm probably all wet on the specifics, but my gut tells me that you can't add another disk without making a change somewhere else.

    Kurt in S.A.

  3. #3
    K Bikes Complex by Choice cjack's Avatar
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    Quote Originally Posted by Isamemon
    so , with fittings
    can a master cylinder for a single disc work great for a dual disc
    I was thinking I could come out of the master with a "t" fitting
    or is it a different bore and more juice
    ( thinking about converting to dual disc and cant find a used dual master)
    You should go from the 14 mm master to the 17 mm master. BMW used to sell a kit to go to dual disks for the R80. It's no longer available and a 17mm master lists at about $416. I wonder if a 14 could be bored out to 17. It's iron. Then buy a rebuild kit for $66. The 17 has two outlets on the front. A tee would work here. I think using a 14 would require a lot of travel. Don't know if it would be unusable.
    R1200GS LC Rallye
    Jack Hawley MOA and RA #224, KE9UW ("Chuck")

  4. #4
    VANZEN
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    what year motorbike ya got?

    I've heard that the early ATE types converted to dual calipers / rotors work quite well with the mc originally fitted with the single.
    (BMW being soooo conservative with their ratios ...)
    Later dual Brembos used either a 14 or 15mm mc, if I'm not mistaken.
    (my '81 is 15mm)

    - both the ATEs & F08s = 40mm / caliper

    check out this chart on mc to caliper ratios:http://www.vintagebrake.com/mastercylinder.htm

  5. #5
    Loose Cannon flash412's Avatar
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    Any hydraulic cylinder which is called upon to move twice as much fluid will have to travel twice as far (lever travel) as it did before the change. Your master cylinder will "work great" as long as you don't mind twice the brake lever travel, and assuming the doesn't hit the grip before the bike stops. Try it and see. If you don't like it, THEN get the other master cylinder.
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  6. #6
    Grammarian no, Rider yes ISAMEMON's Avatar
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    hey
    anyone have a 14 mm master they want to get rid of, free. that i can experiment on, Ill pay shippping
    would also like a 17mm dual disc one to experiment on
    whats in it for you'
    helping other airheads, and maybe you in the future
    Im even interested in trashed calipers
    limited time offer
    I dont need a hundred of em......
    contact me through "pm"
    thanks friends

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