Front Brakes Shaking Truck

Discussion in 'Heavy Duty Diesel Truck Mechanics Forum' started by biofumes, Dec 3, 2021.

  1. biofumes

    biofumes Light Load Member

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    Just replaced the front brakes on a 2002 class 7 sterling(medium duty). Adjusted them correctly, but now the entire front end shakes when the brakes are applied. Could it just be warped drums?
     
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  3. buddyd157

    buddyd157 Road Train Member

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    out of round drums, most likely. warpness is usually rotors.
     
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  4. Rideandrepair

    Rideandrepair Road Train Member

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    Give them a while to break in. Unless it’s an excessive shaking. I’ve had that happen. The shoes aren’t an exact fit as far as the radius is concerned. Usually they cause the wheel to shake a bit when first applied, then it stops shaking. Before auto slacks it was more common. The fix was to back them off a bit, so the rear brakes grab more or first. Maximum Slack travel on steers with 20 size chambers is 1.75” vs. 2.00” ( short stroke) 30 size rear chambers. The drums probably are a bit heat warped like buddy said. I’ve had it happen with new drums, only to have it disappear, after while. Assuming all the brakes are adjusted properly. The drums will wear in with the shoes, especially with hard semi metallic shoes. That’s what I think anyways. Wheel bearings and front end parts should be checked, for looseness. Just in case. Make sure the new shoes aren’t causing a unknown prior issue like a bad tie rod to show up.
     
    Last edited: Dec 3, 2021
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  5. BoxCarKidd

    BoxCarKidd Road Train Member

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    I have had that problem with new drums and the vibration - shimmy was severe. Then bought new drums from the dealer with the same results. Pulled two lug nuts, half way across from each other, up just barely snug by hand. Turned the tire by hand while tighting the slack adjuster. Find the center of the hard spot and tighten the slack hard. Then tighten all the lug nuts. You may have to try that a couple of times to get the over all drag as equal as possible. Test that again by rotating the tire while tighting the slack.
    Something seems out of wack here I know. Hub and the drum pilot are not correct or something. That got us rolling. First one was a 1984 IHC. Some later ones were Volvo White GMCs without new drums.
     
  6. SmallPackage

    SmallPackage Road Train Member

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    I believe 2002 was the last year you could order the old “budd” style stud pilot wheel system on any Freightliner product. Both systems were available until 2003 and then it was all hub pilot. You didn’t say which one it is and they use different center and stud hole size drums.

    New shoes well grab harder like damp shoes do after sitting over a damp dewey night till they wipe the surface rust off.

    Like has been mentioned above. Loose Wheel bearings, king pins, and tie rod or steering link ends, and in rare occasions worn out lazy steering boxes will amplify with new brakes.
     
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  7. little cat 500

    little cat 500 Road Train Member

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    my freightliner did that after new drums the drum is not centering on hub so i took wheels off adjust brake tight put wheels back on then readjust brakes problem solved
     
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  8. biofumes

    biofumes Light Load Member

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    Going to be trying this next, Thanks
     
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