automatic slack adjusters

Discussion in 'Trucks [ Eighteen Wheelers ]' started by 281ric, Mar 25, 2014.

  1. 281ric

    281ric Road Train Member

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    are automatic slack adjusters adjustable yes or no. I hear both yes and no.
    if its out of adjustment , does it mean the slack adjuster is no good?
     
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  3. rollin coal

    rollin coal Road Train Member

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    This one probably open a can of worms. Sometimes if slack adjuster has suffered from lack of grease they will get out of adjustment.
     
  4. Heavyd

    Heavyd Road Train Member

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    There are many different brands and they all have different mechanisms to basically do the same thing. Yes, they can be mechanically adjusted. Some need a tweak here and there to stay with in adjustment, but others like a Haldex are showing something is wrong if the adjustment is out. Some slacks need a good full brake application to engage the automatic mechanism and normal braking just isn't enough pressure to get the ratchet mechanism to pop over. Autoslacks are also supposed to be removed, cleaned, inspected, and reinstalled every so often too, but that never happens and they get gummed up inside. For sure, if they are way out, something is wrong!
     
  5. JohnP3

    JohnP3 Road Train Member

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    I know owners that used synthetic grease in there auto slacks, and other grease in the other things, most auto slacks that come out of adjustment do so because they are not positioned properly or something like the clevis wears. many will remove the slacks and shim them tight to keep the dirt out.
    When you buy a new slack or buy a new truck they come with the gauge, If you buy a new brake pot and the rod is too long the slack will not adjust properly. Many places if you truck came with auto slacks you can not change to manual ones and many places there is a date that all new vehicles must be sold with auto slacks, Same as front brakes
    Just a thought!
     
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  6. Down under trucker

    Down under trucker Light Load Member

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    The thing that kills auto slacks is water. Keep them greased up and they will last for years. On my concrete trucks we cut an old tyre tube and cable tie them over the top to keep the water out and the grease in them. All auto slacks I have seen are manually adjustable. Some have a sleeve over the adjuster the same as a manual slacks that needs to be pushed in, and others have a little tab on top that need to be lifted with a flat head screw driver to adjust. Every now and again they may need to be adjusted, but don't do it too often because adjusting them too often can stuff them
     
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  7. Pablo-UA

    Pablo-UA Road Train Member

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    meritor, BPW, bendix, Haldex make ajusters, IMO, best are Haldex

    all ajusters may be ajusted manually to preset. sometimes they stuck and u have to ajust thm mnually.
     
  8. Flightline

    Flightline Road Train Member

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    I haven't seen any that couldn't be manually adjusted. Not saying there isn't any. I've just not seen any.

    When manually adjusting them, if you get them to tight and have to back them off, you have to force it back over it's ratchet and this is hard on the ratchets which tend to wear them out. So try not go to far on when adjusting them.
     
  9. x#1

    x#1 Road Train Member

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    you can use a flat blade screw driver to lift up on the whatever and then turn the adjustor w/a wrench to the no turn point and then back them off just like using a 9/16's on the old manual adjustors.
     
  10. Flightline

    Flightline Road Train Member

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    Yes, some of them you can lift the ratchet with a screwdriver but not all.
    If I remember the one's with the slide in cylinder around the adjusting nut, is the ratchet lock.

    Kinda ashame we have to adjust what is madated to be automatic but if it gets out of adjustment, we get double fined. Violation for not working properly and violation for being out of adjustment.
     
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  11. GrapeApe

    GrapeApe Road Train Member

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    Lifting the pawl works on the Meritor style, not Haldex.

    In my experience, an out of adjustment auto slack is more often a problem elsewhere, usually the chamber rod the wrong length, worn cam/bushings, or both. Slacks can and do wear out, get rust and dirt that makes them stick, but out of adjustment does not mean that the slack is bad, it only means that it's not working. It relies on other parts to work, so the whole system needs to be checked.

    But to answer the question, you can adjust them. If you find one out and are not in a place to get it checked out, you can adjust it up and keep an eye on it until you get it somewhere for a closer inspection.
     
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