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  1. #1

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    Default Brake rotor / hub not aligned

    My front rotor (Motorcycle Storehouse) does not line up with the bolt holes on my hub. The holes a mm or so out.

    What is the best way to resolve this? I donít want to keep rotors in the hope one will fit eventually.

    Click image for larger version. 

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  2. #2
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    Quote Originally Posted by tiktok View Post
    What is the best way to resolve this?
    You can't use that one...... Buy the correct rotor for that wheel........

    What kind of wheel is that??? You know what year and bike is it off of?????

  3. #3

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    Quote Originally Posted by Tattooo View Post
    You can't use that one...... Buy the correct rotor for that wheel........

    What kind of wheel is that??? You know what year and bike is it off of?????

    74-77 FX. Henry Abe mag wheel. This is the correct rotor for the wheel.

    What is the best way to get this issue resolved? (Without buying multiple rotors in the hope one fits.)

  4. #4

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    That is the correct rotor for a stock, HD hub. No reason to believe it is the correct rotor for your wheel.

    Jim

  5. #5

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    Quote Originally Posted by JBinNC View Post
    That is the correct rotor for a stock, HD hub. No reason to believe it is the correct rotor for your wheel.

    Jim
    It IS the correct rotor for the hub. How can I resolve this problem?

    https://www.instagram.com/p/Bc15OnWH...d=u5vgs2p9p5bl

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    Build a rotor carrier. A circle of steel (kinda like a big washer), that has bolt holes to fit the hub, then drill 5 new holes on the carrier, that are half-way between the hub holes, drill and tap them to fit the rotor, can even have a lock nut on the backside. Done.

  7. #7

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    As near as I can measure an HD hub, the center distance of two opposing holes is 5 31/64 (5.484). Compare that figure to the hub and rotor you have in hand.

    Jim

  8. #8

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    Quote Originally Posted by tiktok View Post
    It IS the correct rotor for the hub. How can I resolve this problem?

    https://www.instagram.com/p/Bc15OnWH...d=u5vgs2p9p5bl
    It's an aftermarket wheel. 1) Your belief that it will accept a factory rotor may be mistaken. 2) Or the rotor may be of poor manufacture. One of those statements is true.

    Jim

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    Quote Originally Posted by tiktok View Post
    It IS the correct rotor for the hub. How can I resolve this problem?

    NO it's not the correct rotor for that wheel, If it was the CORRECT rotor it would fit..........

    The first thing you need to do is stop believing everything you read on the internet..............

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    Quote Originally Posted by JBinNC View Post
    It's an aftermarket wheel. 1) Your belief that it will accept a factory rotor may be mistaken. 2) Or the rotor may be of poor manufacture. One of those statements is true.

    Jim
    DAMN right...........

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    Quote Originally Posted by TriNortchopz View Post
    Build a rotor carrier. A circle of steel (kinda like a big washer), that has bolt holes to fit the hub, then drill 5 new holes on the carrier, that are half-way between the hub holes, drill and tap them to fit the rotor, can even have a lock nut on the backside. Done.
    Won't that off set the rotor????

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    Quote Originally Posted by Tattooo View Post
    Won't that off set the rotor????
    The steel ring is the concept; just gotta be creative.
    If you were to use 6061 or 7075 aluminum for the ring, it could be thicker, you could get a milling machine cut where each 'flange mount' is, so there is kinda an offset on each side...I can see it...but can't draw and post it.
    Accurate measurements would allow the rotor to be in the same plane it was intended to be.

    Further, guessing the replacement rotor may have metric spacing of holes, where the old
    henry abe is good old american standard inches. Who was the supplier of your rotor?

    The standard rotor bolt circle diameter for replacement rotors to fit the Harley, front or rear,
    from Wildwood, for '84 - 2008, and 2008 up,
    is 5 holes on a 3.25" bolt circle diameter.
    https://www.wilwood.com/rotors/Rotor...rcycle%20Rotor

    You said the rotor is for '74-'77 FX; these guys show bolt sizes at 1/4" for the front rotor during that period:

    Fits Sportster and FX models 1974 thru 1977 front with single disc.
    Rotor has 11.5" outer diameter and 1/4" countersunk mounting holes (OEM41807-74).

    Maybe, just maybe, only you can know as you got it in your hands,
    could the holes be enlarged to 5/16", which is common for the front for other years and model, slightly offsetting each one to fit all 5 holes?

    Or even 3/8", as the front/rear of the '72-'78 FLH?

    https://catalog.zodiac.nl/en/catalog...rley-davidson/
    Last edited by TriNortchopz; 01-09-2020 at 3:44 AM. Reason: bcd

  13. #13

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    Quote Originally Posted by Tattooo View Post
    Won't that off set the rotor????
    Space is too tight to permit any offset.

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    You can order a blank rotor of correct thickness, carry that and wheel (ask if they prefer it without the tire) to a machine shop then have them turn and drill the blank to match the exotic wheel.

    The new rotor does not need the silly lobed center of the Sportster/FX rotor used on the Abe wheels and can be machined as a ring with ample support for the bolt holes. It will also cost more to machine a blank with mounting bolt lobes because they'd have to code the task and use CNC. Machine shops drill bolt circle patterns like that all the time and there is a function on any reasonably modern milling machine DRO to space the bolt holes given the correct inputs:

    https://www.youtube.com/watch?v=l8FEThMCL_E

    Online bolt circle calculator example: https://littlemachineshop.com/mobile/bolt_circle.php

    Let your machine shop measure the Abe wheel bolt circle since they're doing the work, unless you have the equipment and want to give it a shot. For ass covering purposes it's worth remembering if the rotor ends up off center the rotor can be bolted to the (tireless) wheel then skimmed in a lathe, or on a mill using a rotary table. Should not be an issue with a machine shop but if you try it yourself having an exit is always nice.

    Example blank rotor, measure the thickness of the stock replacement rotor.

    https://www.kaztechnologies.com/fsae/brake-rotors/

    A machine shop can grind a thicker rotor down a small amount on a surface grinder or a large amount (not desirable because costs more) using a Blanchard grinder. Worth knowing but don't expect to need it.

    If you have other later rotors, lay your Sportster/FX style rotor that doesn't quite fit the Abe wheel over them and see if there's enough metal to machine out the center to match a ring the inside diameter of the lobe. That would let you use an inexpensive later rotor as a blank, and since your're doing a custom caliper mount a different, preferably larger, new rotor OD doesn't matter.

    This stock style rotor might have enough metal in the center and of course will be a usable thickness:
    https://www.easternperformance.com/d...-44136-92.html

    Those old wheels have very limited rotor selection because most bikers avoid them and upgrade. That the Abe wheels with that pattern exist at all is odd but the Japanese market have very specific tastes and run old for the sake of old. Have you contacted the wheel seller direct about buying a rotor?
    Last edited by farmall; 01-09-2020 at 3:21 AM.

  15. #15

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    Welcome to the custom world. There's no telling how many parts I've bought that just didn't work out. I can't count that high!
    This is your brakes, which you will need to work without fail. Your life may depend on it.
    Try to find the correct part and put it together as designed, or hire someone who knows what they are doing to put it together for you.
    Designing a brake setup might be more advanced customizing than you are ready for and I don't mean that in a mean way.

  16. #16
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    Quote Originally Posted by tiktok View Post
    Space is too tight to permit any offset.
    Yep that's exactly what I said..............

    You need to buy the correct rotor for that aftermarket wheel..........

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    As others have mentioned , there is no way to fit. It is not off left or right but up and down Those wheels were made in Japan I believe so, perhaps a rotor from a Japanese bike from the era the wheels were made might work . Unless of course, like Harley, they made a proprietary disc for that bike. Meaning , they deliberately made it an oddball so you could only by the disc from them.
    Just a random thought.
    Last edited by 47str8leg; 01-09-2020 at 10:08 AM. Reason: Grammar.

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    Give us the center point between the holes in the hub. I saw one online in a video of a John Harmon bike. Doesn't have a great shot of the front wheel but it looks like it has a mini disc like an Airhart brake. I have one of those disc brake set ups on a bike I'm doing now. I could let you know.

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