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  1. #1
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    Default Drum brake shoe arc grinding (match drum and shoe radius for max contact).

    For those not familiar, inner drum radius and brake shoe radius rarely match until the shoes are worn in and that can take a LONG time especially on front drums.

    First video https://www.youtube.com/watch?v=T0sdYjuyIYQ shows enough of the cool custom machine to copy. An electric die grinder or router motor would make plenty of power.

    Second https://www.youtube.com/watch?v=d8f9PfrMWss shows a theory of operation and (important) radius setting adjustment using an AMMCO grinder.

    Grinding went out of fashion decades ago because of asbestos dust but it's the only way to match shoe and drum radius for maximum contact. I'd do it outdoors with a blower etc. behind me.

    A pivoting clamp and a belt or drum sander/grinder could get it done. I'm into front discs myself but figure drum guys could use the info. I might make one for my Nortons but it won't be soon. I'll post if it happens.

    You could also use a lathe with a tool post grinder but I wouldn't want the dust all over my shop.

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    thats a cool way of doing it. I have also heard of guys sticking sandpaper to the inside of the drum and rotating the backing plate and shoes back and forth to match the arc to the drum. I haven't done it, but my front drum is pretty awful on my panhead, so I may try and do that soon. I could see doing it this(sandpaper) way as having the benefit of matching the radius of the drum with the shoes engaged rather than turning the shoes to a concentric circle and then having the radii not match when the drum is engaged. I can let you guys know how it works if anybody cares.
    Last edited by gorgeous; 02-10-2020 at 9:13 AM.

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    They cut fine with a well sharpened lathe tool. I usually mount them on the back plate that they will be used on. Then turn about 300 - 350 rpm. Try .020 under the drum diameter but it may need .030. NOS linings are a terrible idea modern linings from one of the vintage brake shops formulated for mechanical brakes are much better.
    In the 60s I worked for Pontiac and old Frank found the cam grinding machine too slow, so he would take a hammer and 2x4 and either hold the shoe lining side up on the table and smack it in the middle with the hammer and 2x4 or stand it on one end and beat the other untill they fit the drum. Course that wouldn't work on cast shoes.
    Dusty

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    Default

    What are "Shoes" ... ??


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    Quote Originally Posted by gorgeous View Post
    I have also heard of guys sticking sandpaper to the inside of the drum and rotating the backing plate and shoes back and forth to match the arc to the drum.
    I've done that many times and it works GREAT............

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    If ya indicate the drum first you can be sure it's reasonably round to ensure steady contact.

    If forget the post but there was one gent who set up a motor and belt on a mill to rotate assembled wheels so the mill could machine distorted drums concentric with the axle.

    Quote Originally Posted by Dragstews View Post
    What are "Shoes" ... ??

    Who made those forks?
    Last edited by farmall; 02-10-2020 at 12:35 PM.

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    Made in Italy by "Ceriani" ..
    ... (GP35MM Roadrace) ...





    Front wheel and brakes came from Sandy Kosman ..
    (Shoot, I go racing every now and again, been out running the Reaper for years)

    I did my own thing with machining out a lower headlight mount and welding it on along with welding the LowRider risers onto the top tree .
    Top Tree was also polished out, but to me was a bit to much shine in one area ...
    Gator boots are early CH ...

    Fork stem has been drilled for routing the fluid to the lines ..



    Wanted to keep the Hi-Lo switch easy to get to....
    Came up with this idea by making a mount that slides into the bar and locks down a 73-81 og switch ...



    Crafty little devil, ain't I ... ?? ..
    Last edited by Dragstews; 02-10-2020 at 3:10 PM.

  8. #8
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    I thunk they might be Cherry Annie.

    Slick idea gun drilling the fork stem.

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    Looks pretty good in the Hummer trim ... I think ..





    Fender, Headlight, Gas Tank and Taillight .. (Although the taillight is a Nos first year K-Model, same light difference bracket)
    Last edited by Dragstews; 02-12-2020 at 12:34 PM.

  10. #10

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    Nice looking bike, but looks nothing like Hummer and has nothing to do with brake shoe arcing!

  11. #11
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    Dang, your right bout dat ...

    If you want me to delete my post, just say so and gone it will be ...

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    Quote Originally Posted by farmall View Post
    If ya indicate the drum first you can be sure it's reasonably round to ensure steady contact.

    If forget the post but there was one gent who set up a motor and belt on a mill to rotate assembled wheels so the mill could machine distorted drums concentric with the axle.



    Who made those forks?
    Don't know if Farm's talking about this video, but it matches the description...

    https://youtu.be/U0BUzEqM-6I

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    That's it!

    BTW if you drilled a piece of plate to take a Harley axle you could also use that plate for wheel bearing shimming.
    Last edited by farmall; 02-13-2020 at 2:52 AM.

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    thanks fer all them vidios

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