Huge THUMP (or THUNK) noise while transitioning... what could it be?

Discussion in 'Fiesta ST Autocross' started by CrookedRacer, Jun 30, 2014.

  1. CrookedRacer

    CrookedRacer Active Member

    I had a disconcerting sound occur that had never happened before in six or so events plus a track day...

    Coming out of a deceleration turning one way, and suddenly accelerating in another, I heard a bad thump from my passenger side front end... like some connection on the strut was shifting somewhere.

    It made me a little more cautious in my driving which hurt my times. Even so, it would make that THUMP sound at the very same place in the course for the rest of the runs. I'd like to sort it out so I can drive it like stink again.

    Has anyone had a similar sound come from their totally stock setup? It was pretty severe.

    And no, it WASN'T a cone! But it was as loud as one being hit squarely.

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  3. Des

    Des Active Member

    I don't get it under those circumstances, but if you don't turn off the hillholder feature you'll get something like that.
    AlanBDahl likes this.
  4. limbo

    limbo Active Member

    I have heard this a couple times as well, no idea what it was I will try to pinpoint it next time I hear it.
  5. iLiptiKal

    iLiptiKal Active Member

    Any chance it was the motor smacking the firewall on acceleration? Or have you changed your RMM already?
  6. Couldahadav8

    Couldahadav8 Active Member

    I heard more of a knock on deceleration with a downshift. It is a bad sound. Mine might be different than yours.

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  7. CrookedRacer

    CrookedRacer Active Member

    Now that I think about it, it was hard deceleration while turning right, and then hard accelerating while turning right. And it didn't seem to be the instant I hit the gas... it was like it was something that was trying to hold on and suddenly lost its grip, released, and allowed something to bang into something else, or allowed itself to shift within some tolerance.

    It really sounded like it came from the strut area, but I suppose it could have been a motor mount of some kind. I don't think it happened as a result of torque on the motor, because I think it would have felt more like like my lead foot had caused it.

    No downshift was involved.
  8. moff3tt

    moff3tt Active Member

    I get something like that every now and then. I always thought it was the e-diff actually doing something. Most of the time I don't think it does anything though.
    Smokin likes this.
  9. Couldahadav8

    Couldahadav8 Active Member

    Talked with an st owner who lost one of the weights on the strut and started to experience a lot of this noise. He heard my car do it. Check your struts for the weights. My weights are there. Maybe it just happens. Car drives fine. ?????

    Sent from my iPhone using Tapatalk
  10. Des

    Des Active Member

    I had a clunk (and something that sounded like a fender liner rubbing); turned out to be a sheared bolt on the rear motor mount.

    Took 'em five days to track it down.
  11. WScottCross

    WScottCross Well-Known Member

    Check that the exhaust isn't hitting something. I had the same thing happen and tracked it down to the exhaust. I do have the Cobb catback, but another FiST owner also mentioned hearing the same thing with the stock exhaust at an autocross. The stock hangars are VERY soft and the exhaust has a ALOT of travel so it could be hitting in the right circumstances.
    Firesail and k757 like this.
  12. Mightymango

    Mightymango Active Member

    I haven't heard any clunks out of mine in transitions yet, but I have heard the exhaust or motor mount could do it. Odd that it only does it on deceleration and turning only one direction. Granted I could have been having the clunk for awhile and have paid no attention to it as my evo makes all sorts of clunks. I'm actually surprised I haven't had any, the car has well over 200 runs on it this year.
  13. The loudest "whump" noise my car has made was during one instance of tire hop. Sounded like I had run over a concrete block (don't ask why I know what that sounds like).

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