Vibration Above 75mph?

Discussion in '2011+ Mustang GT 5.0L Tech' started by Bart23Sept, Feb 8, 2018.

  1. Bart23Sept

    Bart23Sept Junior Member

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    I've got a '14 GT convertible with about 8500 miles, took delivery back in early December.

    It drives great but on the highway, above about 75 mph it starts to vibrate. A local shop put rims on it right after it arrived so I need to let them rebalance the tires/wheels but is there anything in the drivetrain that will typically act up or wear out to make this vibration? It feels like bad road surface but does it in all lanes and on different roads.

    Thanks! Love the car, just need to get it all dialed in.
    Bart
     
  2. RocketcarX

    RocketcarX 95% of my weight is fuel

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    Is the steering wheel shaking or do you feel it in the seat?
    If the tires aren't staggered fir rotate them and see if it goes away, if it does then you had a bent wheel or out of balance tire on the front. Most of the time you can't feel tire balance or bent wheels in the rear.
     
  3. Bart23Sept

    Bart23Sept Junior Member

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    rims only have about 1500 miles on them but i'll ask them to see if they're bent when they check balance. the tires are pirellis, wold they have been on the car from the factory with them?

    thanks for the quick reply

    forgot to say, it isn't just the steering wheel, it's the whole car
     
    Last edited by a moderator: Feb 8, 2018
  4. RocketcarX

    RocketcarX 95% of my weight is fuel

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    Have the tires balanced and when they do ask them to look for bent rims. Double check the driveshaft is tight as well.
    Post a couple of picture of the wheels on the car, plz sir
     
  5. Sky Render

    Sky Render Stig's Retarded Cousin

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    Has the car been lowered?
     
  6. 08gtlarscar

    08gtlarscar forum member

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    Has this car been in an accident ?

    Does the vibration come and go 75-85 or does it get progressively worse with speed ?

    Any suspension mods done to it ?

    Did it vibrate before the wheel swap ?
     
  7. stkjock

    stkjock ---- Madmin ---- Staff Member

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    check for the rotor retention rings on the front discs
     
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  8. Bart23Sept

    Bart23Sept Junior Member

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    Thanks for all of the replies

    These are the rims I put on.
    https://www.tirerack.com/wheels/WheelCloseUpServlet?target=runWheelSearch&initialPartNumber=F388007GB&wheelMake=FLOW ONE Race Spec&wheelModel=F3&wheelFinish=Gloss Black Painted&showRear=no&autoMake=Ford&autoModel=Mustang+GT+Convertible&autoYear=2014&autoModClar=Standard+Brakes

    I suppose it's possible I bent one or more already, there's an entrance ramp to RT 78 that has crazy pot holes right as you speed up to merge (unless your from Pennsylvania, then you don't speed up as you pull onto the highway....no blinker either for some reason usually....lol). I don't recall if it vibrated before the rims were changed. It was only driven from the drop off point directly to the shop where the rims were already there waiting.

    The car hasn't been in an accident as far as I know, carfax was clean, car was like new when I got it with only 7000 miles

    Not lowered (yet)

    The vibrations are like the whole car is vibrating, like turbulence in a plane. It isn't specific to the steering wheel or brake pedal like some other vibrations would be. the whole car shakes. i change lanes and it's still there.

    I've read about the two piece driveshafts but haven't heard of what happens when they vibrate.

    Thanks. I'm thinking it needs to go to the tire shop next week to see about a bent rim or out of balance wheel/tire
     
  9. 08gtlarscar

    08gtlarscar forum member

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    If your wheel/tire setup allows I would do a frt to back rotation followed by a test drive noting results.

    Also a cross rotation with a test drive from the initial starting position of the tires/rims noting results.

    Looking to see if the vibration MOVES with the change.

    As Stjock noted get rid of the retention rings if present.

    Only make 1 change at a time and test drive.

    I always make a good high speed run with a newly purchased vehicle so I can see what I have baseline, If a problem creeps up along the modding process I have a starting point reference, It is a little late for that now though.
     
    Last edited: Feb 10, 2018
  10. 46addict

    46addict 13726548

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    Do you have any more details on the aftermarket wheels that were installed? Hubcentric wheels need to have the same diameter as the hub bore, and if not, a centering ring should be used. For reference, the S197 hubs are 70.3 to 70.6mm depending on who you ask (or you can measure it yourself to verify). A mismatch here can cause a vibration but it shouldn't be shaking the whole car like you're describing. Driveshaft vibration is another possibility but that is a more high frequency vibe kind of like a cell phone vibration and you will see your rearview mirror shake.

    If all wheels are balanced and straight and the problem is still there, I would be looking at axles next. A clean carfax doesn't mean the car is accident free. Repairs done by an individual are obviously not reported.
     
  11. Bart23Sept

    Bart23Sept Junior Member

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    Haven't had time to address it's so still driving it as is.
    Will update when I can look into it.
    Thanks
     
  12. dre256

    dre256 forum member

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    Does the car have any aftermarket performance mods on it? If it does, if you can get under the car look to see if it has a 1 piece or 2 piece driveshaft. Previous owner might have put a 1 piece on and it wasn't put on correctly or its one that is out of balance. If no aftermarket parts are on the car then don't bother, highly unlikely driveshaft was changed.
     
  13. Pentalab

    Pentalab forum member

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    A 1 piece driveshaft needs to have it's pinion angle tweaked precisely. To pull that off, you require an adjustable UCA.
     
  14. 5lho

    5lho forum member

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    Here's a suggestion: Check the bit of cardboard under the front bumper between the bumper cap and the rad support. If this is loose or unaffixed, you'll get horrid hood and cowl shake at speeds 75+.
     
  15. Juice

    Juice forum member

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    My money is on the aftermarket wheels causing the vibration. I bet they have excessive runout on one or more.
     
  16. 702GT

    702GT S197 Fanatic

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    Had a buddy with a '03 Cobra put 18" Saleen's on brand new from AM, had the same vibration issues. Had to take it to 2 different tire shops before one tech identified one of the wheels was not balancing and was out of round. AM replaced that wheel. No more vibes.
     
  17. Juice

    Juice forum member

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    I own a set of AM wheels. One or two cause a slight vibe passing through 65 mph, but smooth over 75.
     
  18. Bart23Sept

    Bart23Sept Junior Member

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    The car finally made it into the shop this week, balance weights were missing from the two front rims. One rim was missing two ounces of weight. I'd guess the weights came off when I hit an area of bad pot holes on an entrance ramp which has since been repaved. They rebalanced the wheels and rotated them and it's much better now.

    Thanks for the replies,
    Bart
     
  19. Sky Render

    Sky Render Stig's Retarded Cousin

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    Glad it was an easy fix!