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Drum Brake Springs

Discussion in 'Early CJ5 and CJ6 Tech' started by eti engineer, Jul 2, 2016.

  1. Jul 2, 2016
    eti engineer

    eti engineer Member

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    I finally got the correct brake shoes for my Jeep and put them on. The part number on the box was exactly the same as the ones I was sent originally, but there is a definite difference between this set and the first one. There is a primary shoe, the shorter one, and a secondary shoe. All shoes in the first set were exactly the same size.

    I still have a problem and need to get some opinions on it. When I put the new shoes on, I turned the cam adjusters all the way in so they would not touch the shoes, the plan being to adjust them once the shoes were installed. The problem is that even with the adjusters not touching the shoes, the shoes still rub the drums.

    When I did the brakes, I put all new lines and wheel cylinders in place, so I doubt these items have anything to do with the issue.

    I have investigated the issue and I have found that if I push the shoes inward at the same time, I can feel the tops of the shoes move inward. Once I do this, the shoes clear the drum and there is no rubbing. It's like the upper spring that pulls the shoes away from the drum is not strong enough to take the shoes that last little bit to clear the drum.

    It seems to me, that on drum brakes, there used to be color-coded springs that one could buy to increase tension over stock springs. Is this the case, or am I confusing this with something else? If not, any suggestions as to what I can do, or am I barking up the wrong tree totally? I hate to spend the money to go to disc, so I am trying to avoid that until it becomes a last resort.
     
  2. Jul 2, 2016
    eti engineer

    eti engineer Member

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    What if I were to grind the tab that fits into the rubber grommet (dust boot) and contacts the piston in the wheel cylinder itself? I could take off maybe a 1/4" off the shoes on one wheel and see what happens? Bad idea? Worth a try?
     
  3. Jul 2, 2016
    timgr

    timgr We stand on the shoulders of giants. 2022 Sponsor

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    I've never heard of different colored springs that have different strengths for these applications. Certainly the suppliers color-code the springs, likely for their own identification purposes. Maybe the color means something in terms of wire size or such - I don't know. A spring kit typically comes through with springs of a few colors.

    Are you using new springs? A Jeep mechanic told me a long time ago how to test brake springs before reuse. Drop the spring from shoulder height on a concrete floor. A good spring will have tight coils, and will make a noise like a pebble. A bad spring will buzz because the coils are opening up.
     
  4. Jul 2, 2016
    Glenn

    Glenn Kinda grumpy old man Staff Member

    Apopka, Fl
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    Grinding would affect how far out the shoe gets pushed, or saying it another way how far the piston would have to extend to push the shoe out.
     
  5. Jul 2, 2016
    1955jeepcj5inabox

    1955jeepcj5inabox New Member

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    Do you mean you can't get the drum on? It rubs so hard I can't turn the drum. Or when you turn it you can hear it rubbing. If it's the last one don't worry, as you adjust the star it will center the brakes in the drum and take up the slack you see.
     
  6. Jul 2, 2016
    eti engineer

    eti engineer Member

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    Glenn, the problem is at the top of the shoes themselves. This is where the rubbing is taking place. The bottom of the shoes is fixed against a stop, but there doesn't seem to be any binding going on there. If there was a total of 1/4" more freeplay at the top of the shoe, I would be clear. I may have to get some new springs as Tim suggested and see if they help. I will do that first, and then if this doesn't work, I will try it on one wheel and see if it works. I am wondering if I have the right wheel cylinders, but they look just like the old ones -- same diameter, same length, etc. I did put a different master cylinder in the jeep as you might recall, along with a vacuum booster -- power brakes.

    I am going to play with this a bit and see what I come up with. Thanks for the help, but I will take more if you come up with something else.
     
  7. Jul 2, 2016
    eti engineer

    eti engineer Member

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    I can get the drums on and they will turn easily with no drag. But once I hit the brakes, the shoes retract, but not far enough to be totally clear of the drum, and there is noticeable drag. If I take the drum off and push in hard on both shoes at the same time, up near the wheel cylinder, I get a little more play out of it and the drum will go on loose again and turn freely.

    I do not have star wheel adjustments on my '62 CJ-5. It is the older cam system. The cams do not even come into play. They have been backed off to the point where they no longer contact the shoes, while I iron out this problem. Thanks for the input. I will let you know what I end up doing to solve this problem..
     
  8. Jul 2, 2016
    Glenn

    Glenn Kinda grumpy old man Staff Member

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    I'd definitely try new springs first. Good springs should take a good bit of effort to stretch far enough to go on the brake shoes.
     
  9. Jul 2, 2016
    eti engineer

    eti engineer Member

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    Hey Tim, how are you doing? Happy 4th weekend, in fact a Happy 4th weekend to all who have taken the time to reply to my issue.

    I finally remembered where I had seen springs of different colors for different strengths. There is a color-coding system used in garage door springs. I knew I had seen something somewhere on this, but at the time couldn't remember what it was for.

    I am not using new springs, but before I modify anything, I will do as you recommend and get some new ones. That may take care of the whole issue. The front wheels are much worse this way than the rear ones, but things are not right. The first set of shoes could not be correct, even though the part number on the first box was identical to the ones I just got. The shoes in the first box were all the same size. That didn't look right to me, based on my experience as a kid with drum brakes. The ones I just got have a definite primary and secondary shoe for each wheel.

    Let me ask you something, directly. I have all new brake lines, cylinders, etc. As you know, I installed power brakes and they seem to have worked fine until the weather got warmer. Can you think of any reason the existing springs would not push fluid back into the master cylinder from each wheel cylinder? The master cylinder and vacuum booster are mounted higher than the the old original master cylinder was, by about 2 feet. I can't picture a couple of feet of extra head pressure of brake fluid in brakelines would create enough backpressure to keep the wheel cylinders/brake shoes from coming to the proper rest point, can you?

    I am off for a few days and I am not traveling. I will play with this situation and see what I can come up with.
     
  10. Jul 2, 2016
    eti engineer

    eti engineer Member

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    Also, Glenn, I have plenty of wheel cylinder travel available to me. The shoes are not that thick, so even totally worn, I would still not pop the cylinder beyond its designed travel.
     
  11. Jul 2, 2016
    eti engineer

    eti engineer Member

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    Thanks to you all for the help so far. Again, have a great 4th, but play safe...
     
  12. Jul 2, 2016
    Glenn

    Glenn Kinda grumpy old man Staff Member

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    Master cylinder pushrod adjustment comes to mind as a possible problem, but I think you might have taken care of that previously.
     
  13. Jul 2, 2016
    Keys5a

    Keys5a Sponsor

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    I would not consider grinding anything off the tabs on the shoes where they mate to the wheel cylinder. Look into stronger springs if you feel they are not retracting properly.
    By the way, its not primary and secondary shoes; its leading and trailing shoes, but we know what you are referring to.
    -Donny
     
  14. Jul 2, 2016
    PeteL

    PeteL If it wasn't for physics, and law enforcement... 2024 Sponsor 2023 Sponsor 2022 Sponsor

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    Since you said you replaced the wheel cylinders, and the problem is "at the top," I have to wonder if the cylinders are causing the issue.

    Possibly the replacement cylinders are not exactly to OEM spec. or are the wrong parts?
     
  15. Jul 3, 2016
    timgr

    timgr We stand on the shoulders of giants. 2022 Sponsor

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    A happy 4th to you too! :flag:

    Regarding the shoes not retracting completely because of the extra height of the master cylinder, no, I think it should not matter.

    Back in the day, it was routine to grind the brake shoes to the same diameter as the drum. Apparently this is no longer done... if I still had trouble, I would be more inclined to remove a little extra lining than remove some steel from the shoe.
     
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  16. Jul 3, 2016
    eti engineer

    eti engineer Member

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    Yes I did. You have a good memory.
     
  17. Jul 3, 2016
    william_cj3b

    william_cj3b 3BOB driver

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    If new springs don't correct the problem, please check your backing plates for wear before your modify anything. The shoes can wear grooves into the backing plates where they contact the backing plate and will cause the same symptoms.
     
  18. Jul 3, 2016
    eti engineer

    eti engineer Member

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    Pete, that crossed my mind too, especially after the first order of brake shoes was so far off, even with the same part number on the box as the second order. The first order of shoes were bonded and the pad area was the same on all shoes -- no primary and secondary shoes, like I said earlier in this post, and the second set of shoes was riveted and had a definite primary and secondary shoe for each wheel. Where do you order parts from? Kaiser Willy's Mike has been good to me so far, but maybe I need to try another supplier.
     
  19. Jul 3, 2016
    eti engineer

    eti engineer Member

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    William, I did check this because as a kid, I once had a 1952 Cadillac that had this problem. Drove me nuts until figured out what was going on. The shoe would hang up on the return and stay in contact with the drum.
     
  20. Jul 3, 2016
    eti engineer

    eti engineer Member

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    Thanks, Tim. I remember having done this as a teenager on some bombs that I owned...
     
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