2011 3.7L Drivetrain Vibration

Discussion in '2011+ Ford Mustang V6 3.7L Tech' started by Jay Beiler, Oct 14, 2020.

  1. Jay Beiler

    Jay Beiler Junior Member

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    Hey all, first time user/poster.

    I am trying to gather feedback on an issue I've been having with my 2011 3.7 V6.
    I have had the 1 piece aluminum driveshaft and 3.73 gears installed at the same time by a local speed shop and they even dyno tuned it.(Shameless brag of 300HP at the wheels. Woot!) Anyway, ever since then, While IN GEAR and OFF the throttle, the rear end vibrates Violently, shaking the whole car, usually at highway speeds but often at any speed as well. The effect is minimal in 6th gear but still there. While under acceleration or in Neutral, there is no issue at all. Did the shop just mess up the install? Should I have the diff rebuilt? I have a friend who runs his own speed shop and he's willing to help but I'd rather get some info before driving 200miles to see him.
     
  2. Juice

    Juice forum member

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    Since you installed a one piece driveshaft, pinion angle comes to mind. Sounds like it is down a bit too far. Under acceleration, the pinion wants to rise, but under decel it wants to drop.
    Jack up the car, install a level app (or get a real angle guage) and measure front and rear ujoint angles.
     
  3. 13v6

    13v6 Junior Member

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    It seems odd to me that if this isn't happening in neutral that it would be your rear end or pinion angle. Or even the driveshaft. Anyway, if you want to check your pinion angle, there is a good video on what to do:

    There is also a good app to use to do this. Just search for "TREMEC Toolbox" in your favorite app store.
     
  4. Juice

    Juice forum member

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    There is no load on the driveshaft coasting in neutral. So the vibration will be much less or not noticable. ;)
     
  5. Jay Beiler

    Jay Beiler Junior Member

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    Would it be beneficial at this point to pull off the upper control arm and swap out the rubber bushing for a poly one. I already have the whole Poly bushings kit from Energy Suspension. Might as well remove the slack due to wear and tear over the years. The car is 10 years old now with 105k miles. Surely those stock rubber bushings are hurting.
     
  6. totaljustice

    totaljustice Junior Member

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    Can you feel any vibration when idling? My 2012 V6 has the same problem when decelerating when the tach approaches 2000 rpm. The car has done it since it was a year old. Dealership told me at the time that it was normal. My mechanic brother tells me it's a bad flywheel. I have driven it the way it is for over 200,000 kms. It's annoying but I hardly notice it anymore. When it fails I'll upgrade the whole works. If you can feel anything abnormal when idling it might be something to look at as well.
     
  7. Jay Beiler

    Jay Beiler Junior Member

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    No vibration at all at idle. When I say violently vibrating, I mean violent. I've gotten in the habit of applying light throttle pressure to keep it from vibrating but it's really compromising the driveability of the car.
     
  8. David Young

    David Young Member

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    It's pretty obvious the gear install went bad. Tell them to redo it :(
     
  9. Jay Beiler

    Jay Beiler Junior Member

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    I have also noticed when coming down from highway speed to a stop, as in taking an exit and waiting at a red light. When I go to take off again, something in the rear of the car rattles like crazy. I think it's exhaust related but it could be gear related. I have emptied the trunk of literally everything, spare tire and hardware too and it still does it. While cold I can shake the pipes by hand and they aren't even close to rubbing on anything.
     
  10. Juice

    Juice forum member

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    Exhaust expands more than you think. Mechanic friends tell me ppl come in with stock vehicles and rattle complaints. Yet, no contact cold from exhaust, but the marks are there where the pipes hit w/hot.

    I'd be back to the shop for atleast to put it up on the lift and do a complete visual inspection.
     
    Last edited: Oct 28, 2020
    GlassTop09 likes this.
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