New GT vibration at high speed

[luca1290]

Hello everybody,

my new GT vibrates at a high frequency when going at high speed, say 120-150 Km/h. Didn't stretch her past that because I'm still in break-in period.
Car currently has 370Km so I should have worn out any flat spots that came during transportation.

The vibration comes in a form of blurriness of what I see from the rear-view mirror. If I touch it, I can clearly feel it vibrating at a high frequency (it's certainly the whole car but being glued to the windscreen kind of magnify the vibration).
Is it a normal feature of the car or should I have my wheels balanced?

Thanks!

Sponsored

 

[Skye]

You're witnessing the vibration in the mirror. Can you feel it anywhere else, like the shift handle?

I don't have experience with flat spots, but...

1. Check tire pressure. Ford and shippers intentionally over-inflate tires.

If the problem continues...

2. Return to dealer to check the following:

- Balance. The wheels and tires should have been balanced at the factory, but a weight might have been lost during shipment

- While on the balance machine, check the rim to ensure it is true. If flat-spotted could maybe see then to? The vehicle has been handled at multiple points by different shippers and means

- While the tires are off, perform a visual inspection of the chassis and suspension. The cars are tied down during transit, especially within the ships

 

[luca1290]

No noise, just the vibration.
It's everywhere, it's just that the rear view mirror makes it more apparent.
I can feel it everywhere in the car, albeit to a lesser degree (it doesn't shake like a washing machine).

Tire pressure is the first thing I checked when I took her home, much overinflated but I was expecting that.
I'll put her on the lift and dismantle the wheels for cleaning, I will check the underside as well.
I'll be bringing the wheels to my tire shop next. I think it's just an out of balance wheel, as it becomes more apparent as speed grows.

I know she's in warranty but I prefer to take care of that personally, I know how the usual shop works and I don't want to end with more problems than the ones I'm trying to solve.

 

[Arknsawchuck]

First thing that pops in my head with an all over high frequency vibration is the drive shaft or something along the drive train like that. Tires normally have a low frequency vibration and can be felt in the steering wheel or seat depending upon if its the front or back.

 

[luca1290]

First thing that pops in my head with an all over high frequency vibration is the drive shaft or something along the drive train like that. Tires normally have a low frequency vibration and can be felt in the steering wheel or seat depending upon if its the front or back.

Uh oh, I wasn't thinking to that, but actually you may be right. I mean, it's scary to think that a brand new car can have an unbalanced drive shaft.
Any way can I diagnose it?

 

[Cobra Jet]

Hello everybody,

my new GT vibrates at a high frequency when going at high speed, say 120-150 Km/h. Didn't stretch her past that because I'm still in break-in period.
Car currently has 370Km so I should have worn out any flat spots that came during transportation.

The vibration comes in a form of blurriness of what I see from the rear-view mirror. If I touch it, I can clearly feel it vibrating at a high frequency (it's certainly the whole car but being glued to the windscreen kind of magnify the vibration).
Is it a normal feature of the car or should I have my wheels balanced?

Thanks!

Your "new GT" is what model year?

The sensation your are experiencing and discussing sounds like a driveline vibration, which could be caused by a few things:
- bad driveshaft guibo (it's rubber, it's known to tear)
- loose or missing driveshaft or guibo bolts
- bad rear diff (usually pinion bearing)
- driveshaft out of balance
- bad trans flange
- bad pinion flange

Check the guibo and all driveshaft bolts first.

If the vibe subsides when you let off the throttle, or vibe sound frequency/feeling increases at certain rpm/speed but drops off at a certain point, is not present at lower rpm/speed OR totally goes away if you are able to put the trans into Neutral at cruising speed - then it's driveline related. A driveline issue will present itself only under "load" conditions at certain peak rpm/speed points.

If it were wheel bearings, the vibe, sound and sensation will increase with speed, it will always be present even in neutral, and get worse when the car leans into that side with the bad wheel bearing. Bad wheel bearings feel as if you're driving on pebbles.

 

[luca1290]

Your "new GT" is what model year?

It's a perfectly new 2022 GT, EU version, with 370 Km all drove by me.

I'll look into what you said in the meantime, thank you.

 

[Arknsawchuck]

Uh oh, I wasn't thinking to that, but actually you may be right. I mean, it's scary to think that a brand new car can have an unbalanced drive shaft.
Any way can I diagnose it?

Not without taking tools to it. If it was an out of warranty car I'd remove the shaft and rotate it 180 degrees and see if that helps. For you with a new car I'd look and see if any weights are missing and if its tight. give it a shake and see if the U joints are bad too. At least then you can info to tell the dealer when you take it in.

 

[NJ3]

Since it's a EU car check for excessive undercoating on the drive shaft.

 

[RagmopInKona]

Uh oh, I wasn't thinking to that, but actually you may be right. I mean, it's scary to think that a brand new car can have an unbalanced drive shaft.
Any way can I diagnose it?

put rear of car on jack stands , chock the front wheel(s) remove rear wheels, put lug nuts back on, to keep rotor from moving, Run it up through the gears till you get to the speed you felt the issue. If it is in the driveline the issue will show when everything is spinning on the stands. If gone, it's in the tire/wheel(s)

 

[luca1290]

put rear of car on jack stands , chock the front wheel(s) remove rear wheels, put lug nuts back on, to keep rotor from moving, Run it up through the gears till you get to the speed you felt the issue. If it is in the driveline the issue will show when everything is spinning on the stands. If gone, it's in the tire/wheel(s)

I have a QuickJack so this is a doable test for me! Thanks!

 

[luca1290]

Ok, did another drive and some math....

The vibration begins at about 130Kmh, progressively becomes worse and disappears at 160Kmh.
Below and after that speed the car is perfect.

Now I did some measurements and the vibration frequency is about twice the rotation of the tires. I suspect I have two tires out of balancing.
The frequency of the transmission shaft is 3.55 times the rear wheels so I'm quite confident it's not the axle.

If I put the car in neutral nothing changes, if she was vibrating she continue doing so. Is she was not, she remains still.

I guess I have an appointment for balancing the tires...

 

[Triton54]

My mirror has had a high-frequency vibration since new, I thought it was normal, it starts at about 75 mph, all the way up to 155. This is with two sets of wheels and tires, the OEM skinnies (255/40/19) and the fatties (285/35/19)

 

[RagmopInKona]

Ok, did another drive and some math....

The vibration begins at about 130Kmh, progressively becomes worse and disappears at 160Kmh.
Below and after that speed the car is perfect.

Now I did some measurements and the vibration frequency is about twice the rotation of the tires. I suspect I have two tires out of balancing.
The frequency of the transmission shaft is 3.55 times the rear wheels so I'm quite confident it's not the axle.

If I put the car in neutral nothing changes, if she was vibrating she continue doing so. Is she was not, she remains still.

I guess I have an appointment for balancing the tires...

You are forgetting this car has half shafts that spin at the same speed as the tires. and why I brought up the idea of, put it on stands , rear tires off, lug nuts tight and run up to the 130km and see if it is still there or not. not there it's a tire/wheel, still there it's in the drivetrain somewhere.

 

[luca1290]

You are forgetting this car has half shafts that spin at the same speed as the tires. and why I brought up the idea of, put it on stands , rear tires off, lug nuts tight and run up to the 130km and see if it is still there or not. not there it's a tire/wheel, still there it's in the drivetrain somewhere.

Did this test.
At first the car freaked out because I forgot to pull the traction control plug in the engine bay .
I checked thoroughly the underside of the car and there are no signs of impacts or scrapes. The transmission shaft is perfect and the balancing weights are all in place. No excessive play nowhere.

As for the vibrations: the car vibrates differently at all speeds while lifted because there are no bushings deading the vibrations and I think the lift has its own ways of transmitting them.

I did not feel a distinct vibration kicking in at 120-130 Kmh, went all the way to 170 Kmh and couldn't feel a big difference, after that speed where the usual vibration already stopped.
Again, the vibrations are felt differently while on the QuickJack and normally I can just feel the rear view mirror vibrating, can't feel it distinctly on the rest of the car.
This time was vibrating, but much less, and was vibrating always at any speed. Again, not like a washing machine, it's something subtle.

Tires? Took a look at them and they look quite ok, maybe a little of flat spots while turning them.

Sponsored