Slapping sound when shifting gears

Discussion in '2005+ Mustang GT 4.6L Tech' started by wdrlaw, Apr 7, 2021.

  1. wdrlaw

    wdrlaw Junior Member

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    2009 GT 5-speed. Hurst shifter, FRPP handling kit (shocks/springs/struts and stabilizer bars), and Steeda adjustable UCA. When I shift gears there is a pronounced slapping sound from the rear/center, around where the UCA bolts onto the frame. I checked the pinion angle after installing the UCA and it was within spec. Because I had never done it before, though, I took it to a trusted shop to double-check and to make sure I had torqued everything to spec. The sound is literally like someone slapping a butt--a big fat butt like mine. I suspect that something is actually hitting the underbody. First, has anyone else experienced this (the sound, not the butt slap)? Second, if something is hitting the frame how can I tell what it is when the car is moving? Finally, did I trust the shop more than I should have? IOW, should I take it somewhere else? Thanks in advance for your help.
     
  2. 07gts197

    07gts197 forum member

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    First, this is in the wrong section.

    Second, do you have a video of this sound?


    Sent from my iPhone using Tapatalk
     
  3. Iceman62

    Iceman62 Bullitt 6005

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    Get underneath the rear w/ creeper & check things out yourself...if this slapping's going on, there's got to be marks in the area(s) of origin.
     
    tbear853 likes this.
  4. wdrlaw

    wdrlaw Junior Member

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    Sorry. Reposted in 2005+ forum. Old eyes.
    No, don't have a video.

    Great idea. Will look tomorrow. Thank you!
     
    Last edited by a moderator: Apr 8, 2021
  5. stkjock

    stkjock ---- Madmin ---- Staff Member Administrator Super Moderator S197 Team Member

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    don't repost threads... moved.
     
  6. 07 Boss

    07 Boss Senior Member

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    Have you ever replaced the bushing on the top of the diff, where the UCA bolts to?
     
  7. wdrlaw

    wdrlaw Junior Member

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    Yes--Steeda UCA came with new bushings.

    @Iceman62: Spent about 20 minutes tonight under the car with a bright LED looking for scrapes, dents, scratches. Nothing other than evidence of very light contact with new jounce stops. The car is about 1-1/2" lower at all four corners--I can no longer fit the jack under it with a hockey puck, unless I drive it onto a 2x10. No visible scratches on diff/axle, UCA, stab or panhard bars, driveshaft, exhaust, or chassis/unibody.

    But I couldn't read what forum I originally posted in, so I might not have seen any marks.

    @stkjock: Sorry for reposting, won't happen again.
     
  8. stkjock

    stkjock ---- Madmin ---- Staff Member Administrator Super Moderator S197 Team Member

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    This is a tech topic please keep on topic
     
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