uneven brake shoe wear

Discussion in 'Trucks [ Eighteen Wheelers ]' started by rollin coal, May 1, 2010.

  1. rollin coal

    rollin coal Road Train Member

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    On my drive axles the bottom shoes look like they're wearing down twice as quickly as the top ones. What's causing that? Also I can hear and somewhat feel when bobtailing what sounds like the rear left side brake dragging slightly. Is there something worn out or needing adjustment?
     
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  2. C16KIWI

    C16KIWI Medium Load Member

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    I had much the same problem and it turned out to be a wheel bearing not adjusted right.
     
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  3. stranger

    stranger Road Train Member

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    The brake return springs are probably weak. The lower one always has weight on it, so it weakens first, letting the shoe hang just a little. When changing brake shoes, always use new springs. They will pay for themselves with decreased shoe wear.

    Also, check your S-cam bushings. If they are worn, the shaft will push sideways when the brakes are applied, and one shoe will press harder than the other.

    It wouldn't hurt to check wheel bearings as stated above.
     
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  4. rollin coal

    rollin coal Road Train Member

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  5. 112racing

    112racing Road Train Member

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    s cams and bushings worn allow the cam to move up and down so it will push on one shoe harder than the other
     
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  6. superhauler

    superhauler Super Crusty

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    yea what they said the pins that hold the shoes in place could also be worn
     
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  7. lastgoodusername

    lastgoodusername Medium Load Member

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    agree with all the above.
    1. pins or their bushings
    2.s cam and it's bushings
    3. i've never had a weak spring, but i have had a broken spring
    4. wheel bearings
    5. bad shoe backing plate
     
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  8. rollin coal

    rollin coal Road Train Member

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    A friend of mine told me to jack up each wheel on the rear axles one at a time and get a pry bar or something under there to pry with to see if there was any play in the wheels. If not the wheel bearings are fine. I did that and they look fine there is no slop. Does that sound right on checking wheel bearings?
     
  9. stranger

    stranger Road Train Member

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    Jack up the rear wheels, put a long pry bar in one of the wheel holes, then try to pick up on the wheel. Any play will show up that way.
     
  10. JohnP3

    JohnP3 Road Train Member

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    Stranger is right on the wheel bearing inspection, if the bearing was loose enough to wear the brake shoe uneven it would have leaked all the oil out and fallen off. With the brakes backed off you can put a screw driver under the bottom shoe and if both the shoes move up and down the "S" cam and bushings are worn, and you have to pull the wheel and change them. Being cheap and thinking you are saving money by not repairing worn brake parts, is not a good thing. That bottom shoe that is worn down, wore out while you were on the throttle. The second set of brakes you may get away with not changing the "S" cam and bushings, if you rotate the "S" cam 180 degrees and have kept the thing greased. Grease is the cheapest repair you will not need. Just a thought!
     
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