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63 Avanti Rear Brake Drums - what gives?

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  • bezhawk
    replied
    You absolutely have the WRONG DRUMS!!!!! A DISC BRAKE REAR DRUM IS 11". I have several NOS in stock.

    Leave a comment:


  • DEEPNHOCK
    replied
    Here's a 'Brakes 201' tip for you.
    Try not to cut any more cast iron off of your drum than you have to.
    The legal max cut is .060" by federal and state law.
    (A 10" drum cannot be cut more than 10.060"..an 11" drum can be cut no more than 11.060"....)
    You are best to just have your machine shop 'clean them up' and 'make them round'...
    If he can do that with a .005" cut...great!
    Oversized (thicker) linings are easy to sand down (with a shoe arc machine).
    You can get a precise fit to the drum that way.
    Hogging out a drum to fit an oversized lining is crazy, as drums are way harder (read that $$) to replace than a brake shoe is.
    HTIH
    Jeff


    Originally posted by brian6373 View Post
    Just got back from the machine shop. He measured the drums and they were .030 under 10". I told him to turn the drums so they were within specs. I'll get them back in an hour or so, and give them a try. I called the nice folks at S.I. and they offered to exchange the drums. Since both drums were the same undersize I figured that the ones in their warehouse are identical to the ones I already have with the same undersize problem. I didn't think that was a good solution. I counter-offered that they could reimburse me the cost of turning the drums to the 10" that they're supposed to be. They said they would have to talk to the owner first and get back to me. To be continued...

    Brian
    Last edited by DEEPNHOCK; 09-25-2013, 09:58 AM.

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  • brian6373
    replied
    Just got back from the machine shop. He measured the drums and they were .030 under 10". I told him to turn the drums so they were within specs. I'll get them back in an hour or so, and give them a try. I called the nice folks at S.I. and they offered to exchange the drums. Since both drums were the same undersize I figured that the ones in their warehouse are identical to the ones I already have with the same undersize problem. I didn't think that was a good solution. I counter-offered that they could reimburse me the cost of turning the drums to the 10" that they're supposed to be. They said they would have to talk to the owner first and get back to me. To be continued...

    Brian
    Last edited by brian6373; 09-25-2013, 07:49 AM.

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  • brian6373
    replied
    Yes, the shoe platforms were badly grooved when I took off the backing plates. I ran a bead of weld and ground down the welds to restore the flat surface that the shoes ride on. Good thinking Warren! Too bad I'm not close to you 37coupeE, I could take my shoes over to you for a demonstration! Great video! I would kill for some of those machine tools! So, if the drums are good I need to reduce the shoe size. As we don't have any old school brakes shops around here that will arc brake shoes. What's a fella to do? Thanks for the help guys, Machine shop opens in about an hour, and I'll find out about the brake drum I.D.

    Brian

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  • DEEPNHOCK
    replied
    Watch this video.
    It gives you a real good idea of the brake shoe, wheel cylinder, and flywheel rebuilding/machining process..

    Last edited by DEEPNHOCK; 09-25-2013, 06:27 AM.

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  • Warren Webb
    replied
    I have seen the backing plates grooved too. Doesn't sound like your problem here but I would check anyway, just to be sure.

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  • 37CoupeE
    replied
    Arcing the shoes is done on a machine that clamps onto the shoe and grinds the lining to the correct arch.
    This is set by locating of the shoe to the grinding wheel.
    Many shops had them in the past to properly fit shoes.
    My dad picked up one years ago when a shop was tossing it out because of the worry of asbestos in the linings.
    Still have it though, because it does come in handy sometimes.

    Leave a comment:


  • brian6373
    replied
    I'm having the exact same problem! I have new shoes, wheel cylinders, and new finned brake drums for the 10" rears on my all drum brakes. The tops of the brake shoes are against the wedge, and the adjuster is all the way in. The parking brake cable is slack. I also insured that the shoes were centered. I compared the old shoes with the new ones and out of the four shoes they all looked to be about the same thickness as the new shoes, except for one that had about 50% of the lining worn down. The drums just won't go over the shoes! The drums and brake shoes are from S.I. I noticed that the drums were made in China, and we all know how the Q.C. from there can be somewhat lacking. I'm taking the drums down to the machine shop tomorrow and have them measured. If it turns out the drums are ok, I guess I'll take the belt sander to the shoes and "calibrate" them! I'll post more after I find out tomorrow about the brake drums.

    Brian

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  • dadondemand
    replied
    Originally posted by 37CoupeE View Post
    Have you tried comparing the new shoes to the old?
    Try measuring the OD of the shoes and the ID of the drum.
    Also are the shoes properly seated up and down and side to side.
    Just some random thoughts.
    I've tried moving the shoes around, in, out, up down, still won't clear. I don't have the original shoes to compare - turned them in to SI when I picked up the new ones.

    Leave a comment:


  • dadondemand
    replied
    Originally posted by studegary View Post
    How much are you missing by?
    Arcing (not "arching") the shoes MAY help.
    Hard to say, but it feels like I'm close. By arcing, do you mean "bending" the brake shoes to fit the arc of the drum?

    Leave a comment:


  • SN-60
    replied
    Originally posted by 63 R2 Hawk View Post
    I know there is a difference on rear shoes between the disc brake cars and the all-drum brake cars, I don't know if it's possible to install the drum style shoes on disc equipped cars, but might be something to look at. In the "old days", brake shoes were made oversized and then ground, or arced, to the exact diameter of the drum by grinding them to fit. Some places will still do that, but that process pretty much went away when it was discovered that asbestos dust was bad.
    Rear drum on disc equipped..11", rear drum on all drum equipped..10"

    Leave a comment:


  • StudeRich
    replied
    It would not be unusual to find some reliners using thicker lining assuming well worn and turned Drums as I have had those same type shoes not fit and had to be Arced to fit some very close to Standard Drums, you also could have your Machinist Mic the drums to see just how big they are.

    You do know those are relined, as New is not available.

    Leave a comment:


  • 37CoupeE
    replied
    Have you tried comparing the new shoes to the old?
    Try measuring the OD of the shoes and the ID of the drum.
    Also are the shoes properly seated up and down and side to side.
    Just some random thoughts.

    Leave a comment:


  • studegary
    replied
    How much are you missing by?
    Arcing (not "arching") the shoes MAY help.

    Leave a comment:


  • dadondemand
    replied
    Originally posted by Studebakercenteroforegon View Post
    How about the emergency brake adjustment? You should back that off as needed also.
    Both emergency brake cables are presently disconnected, so they're not a factor in the positioning the brake shoes.

    Leave a comment:

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