Which auto slack adjusters?

Discussion in 'Trucks [ Eighteen Wheelers ]' started by ParkerFly, Feb 7, 2016.

  1. ParkerFly

    ParkerFly Bobtail Member

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    Apr 11, 2012
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    I'm getting ready to convert my W900A and trailer over to automatic slack adjusters. I've seen several different brands, mostly Gunite and Meritor but others too. Is one really better than the other? Or is it like Ford and Chevy just pick what you like and go with it? Thanks for any help.

    Justin
     
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  3. mhyn

    mhyn Road Train Member

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    I would choose meritor or haldex. gunite broke twice on my trailer.
     
  4. kwcam

    kwcam Light Load Member

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    Haldex is the best from what I've had to work with over the years, very few if any failures.
     
  5. mp4694330

    mp4694330 Road Train Member

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  6. mhyn

    mhyn Road Train Member

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    Haldex has clearance-sensing design and pin must be installed above slack adjuster. Meritor does not have pin to install. it has stroke sensing design.
     
  7. GrapeApe

    GrapeApe Road Train Member

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    Haldex and Meritor are the most common and are both good. I prefer Haldex, it only requires a 7/16" wrench to adjust. Meritor needs a 5/16" open end wrench or square socket and the pawl needs to be lifted to back them off. Bendix makes a decent slack as well, but more suited for hard braking applications.

    Haldex and Meritor are about even as far as performance. If you run a lot of local hills and P & D, I recommend Bendix slacks. They are a bit slower to adjust, which is good for hard brake usage. When you do a lot fo down hill braking or stop & go type driving, the drums expand more from the heat. It's possible for a Meritor or Haldex slack to take up that slack and make the brakes too tight when they cool. If your application requires a lot of braking, long stroke chambers with Bendix slack are better.

    Whichever you decide, be sure to read the directions and set them up correctly. I have seen many more slacks replaced than I have seen bad slacks. If they are not set up correctly, they will not adjust correctly. Chamber rod length is very important, more so on a Meritor and Bendix. A Haldex is more tolerant of wrong push-rod length, but it still hurts braking force if it's wrong.
     
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  8. AModelCat

    AModelCat Road Train Member

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    Make sure you use the right clevis for whatever slack adjuster you choose. Some clevises have 2 pins: a main pin and one for the adjuster. The distance between these pins will be different depending on which brand you decided to use. I had a truck roll through the shop a couple years back that had the wrong clevis (spacing between the 2 pins was too much) on 2 of the wheels and it caused the brakes to not adjust correctly. It also wrecked the slacks and bent both pushrods. The remaining 6 wheels with the correct clevises were fine.
     
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