Loud "thump" noise from rear suspension

Discussion in 'Suspension, Brakes & Chassis' started by K-Roll302, Jun 17, 2020.

  1. K-Roll302

    K-Roll302 Well-Known Member

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    I've got an annoying and very audible thumping sound from my rear suspension on certain road conditions. It's loud enough that it'd make someone believe that either something heavy fell in or was tossed into the trunk (everything is secure there), or I was bottoming out the rear end. I've heard it most noticeably on humps on the road, driving over a manhole cover, and certain dips and imperfections, some of which are much too shallow for the suspension to bottom out. I'd gotten shorter bump stops to go with my Steeda Progressives and shock mounts thinking it was bottoming out, but that didn't do the trick.

    I'm wondering if it could be worn out rear sway bar links or even the bushings (all OEM), after 46k miles of Michigan roads? Has anyone experienced such a noise and issue?
     
  2. Rapid Red

    Rapid Red Well-Known Member

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    Off the top of my head.

    Get the car in the air have a look. When did it start after "Steeda Progressives and shock mounts" up grade, was the car lowered?

    Something is loose or there is a clearance problem, not sounding like drive train.
     
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    K-Roll302

    K-Roll302 Well-Known Member

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    I installed the springs in the winter of 2017, and I only remember the noise as far back as summer-fall 2019. I'd installed the shock mounts and bump stops while the sound had already existed, the former last fall and the latter a month or two ago.

    Getting the car up is the only way to know for sure, I'd just like to narrow it down based on potential past experiences, before I dive in and start going everywhere and anywhere under the car. I'm leaning more towards the idea of something being loose.

    EDIT: Something I forgot to note, was that the thump is much louder when I hit a hump in the road at a higher speed than slowly driving over it. I can produce the sound above 25mph, but not if I'm at a crawling pace around 15mph or lower. I can make a video clip later today if it'd help any.
     
  4. OF5.0

    OF5.0 Well-Known Member

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    When you lowered the car, did you clock the suspension bushings?
     
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    K-Roll302

    K-Roll302 Well-Known Member

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    I had the dealer clock the bushings not too long after lowering the car.
     
  6. Roadway 5.0

    Roadway 5.0 Strassejager

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    Double check that your tire inflate kit is very snug in the spare tire wheel well. You can remove the whole kit to test if that helps too.

    Also check that your backseats are fully latched to the chassis. They comes loose at the edges often, especially if you have kids.
     
  7. moffetts

    moffetts Well-Known Member

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    There’s a lot of things in the rear suspension (and rear of the car in general) that can make clunking noises, unfortunately. If it's not something simple like the tire kit or the rear seats, lift the car up and check all of the bolts for proper torque. Also check the swaybar to exhaust clearance.
     
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    K-Roll302

    K-Roll302 Well-Known Member

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    I'll check the rear seats and tire kit for now and see if there's a change on the drive home after work. Then I'll have a look underneath when I get home.
     
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  9. givemeadollar

    givemeadollar Well-Known Member

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    the nut on the top of the rear struts. Mine managed to work its way loose even with red locktite and made a stupid clunk noise when I hit just about any size bump.
     
  10. AlbertD

    AlbertD Well-Known Member

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    It is fairly common for the diff bushings to prematurely fail, specifically the driver side. You may want to consider checking the diff bushings for any tears as that could certainly lead to excessive NVH.

    My bushing was torn all the way through with about 45k miles.
     
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    K-Roll302

    K-Roll302 Well-Known Member

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    I'll have to give those another look. I replaced the hardware with new nylock nuts and a dab of blue locktite when I did the billet shock mounts not even two months, and I'd be shocked and impressed if they came loose even the slightest bit.

    I wasn't aware of diff bushings failing prematurely, thank you for that heads up, as I'm at just over 46k miles! Whereabouts are those located under the car?
     
  12. AlbertD

    AlbertD Well-Known Member

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    More info and some pictures within this thread: https://www.mustang6g.com/forums/threads/torn-diff-bushings.138653/

    If you look under the rear of the car... right above the diff within the black IRS cradle... you will see two rubber bushings in the cradle supporting the diff... driver and passenger side. Easy to check in a quick glance...

    Here is how my driver side bushing looked... I had some thuds/clunks over rough patches of road.

    upload_2020-6-19_11-29-57.png
     
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    K-Roll302

    K-Roll302 Well-Known Member

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    The fact that I'm hearing the noise most noticeably on my driver side than my passenger side is sounding suspiciously like this, even though I'm just now getting under the car.

    And HOLY CRAP, this looks like a job from hell, just for a daily driver. No way Ford would cover this sorta thing under warranty at this point haha. I'll let ya know what I find.
     
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    K-Roll302

    K-Roll302 Well-Known Member

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    I just noticed that I've got some square dampers in the way on mine compared to yours...It's gonna take me a bit to remove those.
     
  15. moffetts

    moffetts Well-Known Member

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    Those square damper things were only present on EB cars of that generation. The bushings are a pain to replace and OEM bushings are not available at all; they are considered part of the subframe. The good news is, there is a good chance your noise will have a simpler resolution than that.
     
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