Front drum brake shoe replacement difficulties
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  1. #1
    Junior Member Both0703's Avatar
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    Front drum brake shoe replacement difficulties

    Hi Everyone,

    I'm in the final stages of sorting out my 1972 CL350, and thought I'd see if I could improve my brake performance by swapping the old drum brake shoes for new ones. I had already replaced an aged front brake cable successfully and adjusted front and rear according to the specifications in my Clymer Manual, but the stopping power, particularly on the front, still seemed poor compared to other Hondas I've ridden with the same brake components. I ordered a set of shoes for the front and rear from Common Motor Collective and took a stab at it this weekend. The rear went very well, and the stopping power has clearly improved dramatically. The shoes were easy to install, fit very well, and I did a full rebuild following the directions of this video.

    Following the same procedure, adapted slightly because of the two pivot points rather than the single on the rear drum, I cleaned and rebuilt the front as well. Upon putting it all back together, I found that front wheel seemed to be binding on the new shoes in a number of places without applying any pressure to the lever on the drum, which did not happen with the old shoes. I also determined that my cable is no longer long enough to reach the hand lever effectively. The arm on the brake assembly had approximately 1/2 inch of free play (with pressure applied by hand directly to that lever) before the shoes made contact with the drum with the old shoes installed, which was enough that I could attach the brake cable and adjust it properly. The new shoes allow the arm on the drum somewhere between 1/8th and 1/16th of an inch of free play before engaging, and I can no longer attach my brake cable, in addition to the binding at certain spots on the wheel. I've attached two pictures of how I put everything back together. Please note that I realize I did not install the exterior return spring on the brake assembly that attaches to the primary lever, and ignore the "1" and "2" written on the brake shoes - those were my own marks while I while tried swapping the shoes from side to side to see if that affected the issues. The new shoes are EBC Brand and the cable is 52 inches long from one end of the pull knob to the other, purchased from Charlie's Place.

    Since I'm sure many of you are more knowledgeable and experienced than I am at this, could you please let me know if you see anything that looks out of sorts? Any information or suggestions on how to resolve this would be greatly appreciated. I've reached out to Common Motor Collective Tech support as well and am awaiting a response, but I figured getting multiple perspectives couldn't hurt. Thanks in advance for your thoughts.

    Front drum brake shoe replacement difficulties-img_6928.jpg Front drum brake shoe replacement difficulties-img_6929.jpg

  2. #2
    Sensei 66Sprint's Avatar
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    A quick phone call should solve this for you.......
    "I have a mind like a steel trap.....Old and rusty, of antiquated design, and hard to get stuff back out of...."
    Contact info: E-mail; [email protected] Phone; 540-525-5199

  3. #3
    Senior Member mikemill's Avatar
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    I'm facing a very similar issue on my 1973 CL350. I followed the same video and had no trouble at all with replacing the rear brake shoes. When it came to replacing the front shoes, I assembled the plate like you did above, and had some difficulty getting it into the hub because the brake shoes were wide. When I installed and torqued the axle, the wheel was COMPLETELY BOUND UP. Removing the plate with the shoes on was a nightmare because the shoes kept sticking. Then I assembled the hub and brake plate without shoes at all and it spun freely. So I know it's the shoes and not the bearings or something like that. Measuring the inner dia of the hub and the installed outer dia of the shoes yielded the same measurement -- 179mm. So it seems like there is nowhere for the shoes to expand as they are already up against the steel lining of the hub. Additionally, the main brake arm barely moved (maybe 1/16") like yours, which supports the theory that the shoes are just too wide.

    I have ordered shoes from 2 different suppliers (4into1 and CMC) and they both sent the same EBC shoes and both behaved the same way. I am completely stumped and don't know where to go from here.
    1973 CL350 - Project Log

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  5. #4
    Senior Member mike in idaho's Avatar
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    The shoes need arced to fit the drum. Take the assembled backing plate,with the front wheel and axle parts, to someone with a lathe and have them chuck it up and turn the od of the shoes to .020" less than the drum diameter. That will give you almost 100% braking performance immediately with very little bedding-in miles needed.
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  6. #5
    Senior Member brokencamchain's Avatar
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    Back in the day I worked in a NAPA independant jobber/machine shop and arcing shoes was something I did on roughly a daily basis. We had a sander (much like a verticle drum sander) and a sliding carriage to which the shoe was attached and you slid the shoe up to the drum and it then was swiveled from side to side (the arc) removing material with each pass. I dont think they do this any longer though but I could be wrong (and often am). I would be curious to see how much larger the new ones are and how much material would need to be removed. Installing the old shoes and measuring the distance across the outside of the two shoes (diameter) may give you a ballpark figure you need to work with (assuming the shoes are not totally worn down) and apply that measurement to the diameter of the new shoes would tell you how much material needs to be removed.

    I like the idea of using a lathe, I used to "Turn" drums but never shoes--it sounds like a good solution though. I am facing this same situation on my CL450 so I am interested in the outcome.
    Bryan
    1973 CL 450 (work in progress) 1970 spare engine
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  7. #6
    Sensei 66Sprint's Avatar
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    While the use of a lathe for this purpose is ideal, most members don't have one.....
    Remember that machine tools were created to expedite processes that previously were all done by hand.....
    You CAN "arc" the shoes by carefully using a hard rubber sanding block and some 40 and/or 80 grit sandpaper.....

    Assuming a situation like the examples presented (where the OD of the shoes, and ID of the drum are both 179 mm),
    you are going to have to remove approximately 1/4 mm (0.26 mm or 1/64") of thickness to achieve the proper clearance of ~.01" all around/.02" difference in diameters.... (Please verify my mental calculations)
    YES, it IS a PITA, but you won't have to wait for a machine shop to "get around" to doing it, or have that expense.....

    IF "Pops" Yoshimura could hand sand the final honing process in cylinders for his race bikes (and he did), surely you can arc and fit brake shoes by hand........
    Last edited by 66Sprint; 11-06-2019 at 11:12 AM.
    "I have a mind like a steel trap.....Old and rusty, of antiquated design, and hard to get stuff back out of...."
    Contact info: E-mail; [email protected] Phone; 540-525-5199

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