SOHC CB750 tech question (performance brakes)

Discussion in 'Old's Cool' started by Houseoffubar, Jan 11, 2011.

  1. Houseoffubar

    Houseoffubar HoFmetalworks.com

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    Hey there, I'm using a '75 CB750 front hub on my Airhead, and am trying to find a good upgrade disc off of perhaps a late model Honda. I'm planning to only use one disc, so I need a fairly big one. I only care if the 6 bolt ,and the center hole pattern fits, The offset does not matter. This is the hub I am using.
    [​IMG]

    Thanks for your suggestions!
    #1
  2. Tosh Togo

    Tosh Togo Long timer

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    You might contact Buchanan's for ideas, as they've probably seen enough conversions like your idea to know what works and what doesn't.
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  3. slashbike

    slashbike Been here awhile

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    EBC makes a prolite rotor for the CB750....In my experience with it, it takes brakes that would barely slow you and turns them into brakes that'll squawk the front tire... for more single-cam tech than you ever wanted, check out www.sohc4.net .
    #3
  4. nella

    nella Been here awhile

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    Are you planning to use the stock single caliper 100/7 front fork or something different? If you are using the stock forks it's going to limit your options for a disc because the design does not allow you to move the caliper out to fit a larger diameter disc.

    Anyway, you will need to get a measure of the offset you will need once the hub is centered on the axle, the center bore, and the correct disc diameter. An aftermarket cb750 disc may or may not be what you need. A quick search on google seems to indicate the diameter of the cb750 disc is 295mm. The 100/7 disc is around 260mm.

    Edit: not sure why you say them offset does not matter unless you are planning on a spacer
    #4
  5. Houseoffubar

    Houseoffubar HoFmetalworks.com

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    I guess I should be a little more clear, however, it is hard to explain, other than to say that as long as there is some offset, to get the GSXR caliper away from the spokes, it will be OK.

    I'm using a caliper mount that does not attach to the fork leg at all. The caliper will be attached to a bracket, that is mounted to the axle, and the lower triple clamp, making a mechanical anti dive. BTW, I am using Suzuki 1200 Bandit forks. Here is a poor photo of the system.
    [​IMG]

    Thanks for the help so far!!!
    #5
  6. nella

    nella Been here awhile

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    Sounds interesting! I see what you are trying to do. Not sure with modern forks that anti-dive setup would make much of a performance difference but I'm the first to admit that that is not always the point.

    I'd suggest finding an old cb750 rotor to test fit and go from there.
    #6
  7. bk brkr baker

    bk brkr baker Long timer

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    The whole anti-dive thing was hot for a while. Mechanical, hydrolic, brake activated all sorts and the it just went away.
    Seeking an answer to a non-problem?

    Or a cool looking farkle?

    If you get it right the front will work normally, if it's wrong it will get too stiff and the tire may skate.
    Good luck.
    #7
  8. Houseoffubar

    Houseoffubar HoFmetalworks.com

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    The beauty of this design is it is the one design that truly worked. it does not effect the suspension at all, unlike damping operated anti dive. This system simply holds the weight of the bike up in exact proportion to the amount of braking. It is also easily tuned, by shortening or lengthening the mounting position of the vertical rod from the axle (horizontal distance) one can have slight dive, no dive, or even lift under braking.
    This system also takes the force applied to the caliper under braking, and applies it to the lower triple clamp. This removes the added stiction of the lower fork leg being both pushed back at the axle under braking, and also pushed forward at the top of the leg due to the calipers applied force. This causes a small amount of fork twist for single disc bikes as well. By applying this force to the lower triple, this twist is eliminated.

    So if it is so great, why does every bike not have this from the factory?
    In my opinion, production bikes must be near fool proof, and the vertical rod this design uses, has a LOT of force applied to it under braking. If it were damaged through abuse, or even road debris hitting it, it would almost certainly collapse causing a near certain wreck! Not good for the manufacture trying to avoid lawsuits!

    Riding a bike with this system, or similarly the Earles fork is pretty amazing! even at high braking levels, the fork does not bottom, and responds to even slight bumps in the road. It is very confidence inspiring in the feel it gives the rider, when braking over rough surfaces at speed!
    #8