Unusual vibration

[brucelinc]

I know there are other threads about vibrations but my issue seems different.

Up until about a month ago, my 6500 mile 2018 GT was smooth at all speeds. Now I have a vibration through the steering wheel beginning at around 48 mph and stopping at around 53 mph. It is ONLY during that narrow range. High speeds are perfectly smooth.

I had all 4 tires road force balanced and wheels checked for run-out. Everything checked out perfectly. I even tried a different pair of wheels/tires on the front and it made no difference.

Any thoughts on what could cause this at such a specific and narrow speed range....and start all of a sudden?

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[88lx50]

Driveshaft possibly?

 

[brucelinc]

I am wondering about the driveshaft. Doesn't seem like that would be felt through the steering wheel but it is possible, I suppose. I ran the car at the strip about a month ago and it was just after that when it started but I am not sure that has anything to do with it. I am going to have a Ford tech drive it and see what he says.

 

[Lo Pony]

Bruce, is it airplane propeller or shake/shimmy in steering wheel?

Back and fourth shimmy shake in steering wheel is not drivetrain, which would be like a subwoofer in the car on a sustained bass note...more of a buzz/roar. Drivetrain is generally 50-60 Hz. Wheel related, more like 5-10 Hz. If the latter, might be rear axle related, downstream of pinion.

 

[brucelinc]

Lo Pony, there is no noise at all. There is no shimmy, either. If I let go of the steering wheel, I feel nothing through seats or accelerator. It is the same regardless of the gear I am in and applying brakes makes no difference. At that specific speed range, the steering wheel vibration reminds me of what I feel through the handlebars of an idling motorcycle.

I did install a GT 350 axle on the driver's side last February. I have since checked the torque on all the bolts/nuts involved in that as well as the cradle bolts and everything is at spec. That axle is heavier than the stock axle but there was no vibration until recently.

 

[Zinc03svt]

Bruce, you can run a larger axle on just one side? That sounds like trouble to me. Hope you get it sorted.

 

[brucelinc]

The GT 350 and manual transmission GTs have a heavier axle on the driver's side than on the passenger side.

The reason I don't think the axle is the issue is that it was fine for several months after installing the axle. This vibration just started a few weeks ago.

It is not really a severe vibration. Since it only occurs in a specific speed range, I coyld probably just live with it. I am still suspicious of a tire issue. I have a friend with a Mustang and we are going to do a temporary tire/wheel swap this weekend so I can positively rule out a tire problem.

 

[offroadkarter]

Have you had the alignment checked?

 

[brucelinc]

Have you had the alignment checked?

No, I have not but once I rule out a tire issue, I will get it checked.

I had a Ford tech drive it yesterday and he was convinced it was a tire issue. I will find out this weekend when I swap with a friend.

 

[JimGT]

Similar vibration started for me at 2000 miles... 2 different dealerships and about 8 trips and no fix... They road force balanced tires twice, replaced a tire, new front wheel bearings, clocked the driveshaft.. no change.. I bought a QA1 Carbon Fiber driveshaft hoping to get rid of it.. didn't fix it.. decided I would live with it instead of my car living at the dealerhsip. Has now gotten worse at 14000 miles and now vibrates at 80 as well to the point the mirror is vibrating badly... Guess I will take it back to another dealership and try again.. After the front wheel bearings I got a new noise when coming to a stop, like a bad bearing so they probably screwed that up.. Very frustrating these days going to dealerships.

 

[Jetnoise]

to the point the mirror is vibrating

Same issue here....
Expert & Experienced Service writer told me to get lost....with all my first service visit concern list issues.
What kills me is when I dropped it off I offered to take them for a ride to clearly demonstrate my concerns...he told me it was a technician's responsibility to trouble shoot it and they would.
Go to pick it up....turns into he (service writer) and the "shop foreman" test drove it and found no issues.
Cross Roads Ford in NC is not on my list anymore for service. Waited 3 weeks for the service appointment and they didn't do jack....
Ok I'm done B*tching

 

[Triton54]

Bruce, if you need another set of wheels, and tires, you could try mine, just under 11,000 miles and zero vibrations, except in the rear view mirror, at higher speeds...

 

[brucelinc]

FOLLOW UP:

Thanks for the offer, Triton54!! I did try a different set of tires/wheels and there was no difference at all in the vibration. I took my car to the dealer and a tech confirmed the speed specific vibration. He did all sorts of diagnostics and even involved Ford Engineering. Ford wanted the tech to make sure the rear cradle was in alignment but it was perfect. Based on some sort of electronic test which I do not fully understand, they concluded that the center bearing on the driveshaft was allowing a slight "whipping" motion of the shaft at a specific speed. New driveshaft is ordered.

I am baffled as to how a driveshaft vibration can cause a steering wheel vibration but no issue through the seat or accelerator pedal. In any case, the shaft is going to be replaced. I just hope they don't make it worse.

 

[Lo Pony]

Let us know, Bruce, that sounds weird, but hope you get it fixed.

 

[Zinc03svt]

Hope that is the fix Bruce. I can imagine it has been annoying. So did it start out of no where randomly?

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