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Thread: Single to Double Disc Brake Swap

  1. #1

    Single to Double Disc Brake Swap

    I'm starting out on a brake upgrade for my R75/7. My plan is to change from the single disc to a double disc, Brembo 4-spot system. So far I have a pair of front forks from an R100R and both Brembo calipers. From what I understand, I'll need to mill 4mm from each caliper mount. I had lanned on using floating discs and a spoke wheel.

    I have read that this modification may only be possible on a snowflake rim. Has anyone completed this mod on a spoke rim? If so, which rim (year/model)?

    Also, what hoses are used? I believe that the hoses from a K100 will work or possibly an R1200. Any help would be appreciated.

    Thanks!
    Mark

  2. #2
    Liaison 20774's Avatar
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    Mark -

    Welcome to the forum! Good luck on your upgrade. I don't have any direct experience or knowledge...others will chime in. But check out Snowbum's website, particularly this page:

    http://bmwmotorcycletech.info/brakes.htm

    Anton Largiader has a page on brakes which might provide some additional background:

    http://www.largiader.com/articles/brakes.html

    Also, check out the link in my signature block to see other information and resources for BMWs.
    Kurt -- Forum Liaison ---> Resources and Links Thread <---
    '78 R100/7 & '69 R69S & '52 R25/2
    mine-ineye-deatheah-pielayah-jooa-kalayus. oolah-minane-hay-meeriah-kal-oyus-algay-a-thaykin', buddy!

  3. #3
    Registered User AntonLargiader's Avatar
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    What front wheel are you planning to use? If you are swapping the entire R100R front end, then just go with a handlebar-mounted MC and the R100R hoses.
    Anton Largiader 72724
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    Virginia Motorrad Werkstatt BMW motorcycle service and repair in central Virginia

  4. #4
    Quote Originally Posted by AntonLargiader View Post
    What front wheel are you planning to use? If you are swapping the entire R100R front end, then just go with a handlebar-mounted MC and the R100R hoses.
    Thanks Anton. I'm not sure about the rim yet. I have calipers from a 1999 R1100RT and forks from a 1982 R100RS. So far, so good.

    I wanted to try and keep the under tank master cylinder. For this, I think I can use the hose set from a K100. Since the calipers came from an R1100Rt, it may be easiest just to use that hose and rim set.

    Who will be a reliable supplier for the rim?

  5. #5
    Registered User AntonLargiader's Avatar
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    Quote Originally Posted by geldmacher View Post
    ...So far I have a pair of front forks from an R100R and both Brembo calipers.
    Quote Originally Posted by geldmacher View Post
    I have calipers from a 1999 R1100RT and forks from a 1982 R100RS.
    Well, you need to decide on what forks you actually have. Those two bikes have different forks with different axles which accept different wheels. Spoked wheels are difficult with the early '80s forks due to clearance issues. I think you need to research this a bit longer. Search the web for people who have attempted or achieved this and see what problems they encountered.
    Anton Largiader 72724
    Tech articles - YouTube
    Virginia Motorrad Werkstatt BMW motorcycle service and repair in central Virginia

  6. #6
    Quote Originally Posted by AntonLargiader View Post
    Well, you need to decide on what forks you actually have. Those two bikes have different forks with different axles which accept different wheels. Spoked wheels are difficult with the early '80s forks due to clearance issues. I think you need to research this a bit longer. Search the web for people who have attempted or achieved this and see what problems they encountered.
    Thanks Anton, that's just the advice I'm looking for. I'll really need to confirm the fork config. The listing said, "1982 R100RS". I should be able to measure the axle size easily enough. I'm more worried about the spokes hitting the calipers.

    Thanks again
    Mark

  7. #7
    Registered User jad01's Avatar
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    I might recommend keeping your upgrade simple by adding a second ATE caliper/lower fork slider and a dual fitting MC. I did that on my /7 and it provides all of the braking I could ever use. Much (much, much) better than the single caliper. Then you could retain your existing spoked wheels.

    Alternatively, it might be good to look for a complete front end from a later bike (early '80's era would be my choice), but I do think you'd have to commit to cast wheels (snowflakes or maybe Lesters).
    Jim (MOA 83200)
    '78 R80/7 (Anastasia) and '84 R100RS (The Millennium Falcon), '86 K75C (Icy Hot)
    '90 and '93 Mazda Miatas (Jelly Bean and Red Hot), '97 Nissan XE PU (Mighty Mouse)
    '96 Giant Upland (big Kendas, baby!)

  8. #8
    Quote Originally Posted by jad01 View Post
    I might recommend keeping your upgrade simple by adding a second ATE caliper/lower fork slider and a dual fitting MC. I did that on my /7 and it provides all of the braking I could ever use. Much (much, much) better than the single caliper. Then you could retain your existing spoked wheels.

    Alternatively, it might be good to look for a complete front end from a later bike (early '80's era would be my choice), but I do think you'd have to commit to cast wheels (snowflakes or maybe Lesters).
    I would second the idea of just doubling the ATE set up. Simpler, more acceptable to the purists, and probably going to give you more than enough stopping power.

    Further, it is not clear from your posting if you just have the R100R fork sliders/stanchions or if you have the related triple tree/clamp/yoke. As Anton says you quickly need to become an expert on axles sizes/types, wheels, fenders, etc. More reasons to think why doubling the ATE set up makes sense.
    Mark

    Current ~ '74 TR5T : '93 R100R : '99 Gran Canyon : '06 ST3s
    Past ~ Variety of British, French, Italian, Czechoslovakian, & German bikes

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