You're essentially correct however speak only interms of frequency. The rotational relationship between the driveline downstream of the transmission and the hubs/wheels/tires is dependent on the final drive ratio of the axle. Depending on the final drive ratio of the rear end gears, the driveshaft is going to rotate between 3 and 5 times faster than the hubs/wheels/tires making the driveshaft out of balance frequency 3 to 5 time higher than a hub/wheel/tire. In either case, amplitude is subject to degree of out of balance and it's rotational speed. Make sense?

Regards,
John

 

John,
Makes perfect sense to me. I'm wondering if an after market driveshaft which is well balanced would fix the issue.

 

It might but might also introduce unanticipated issues as well. Read the last post here made by CDYNACO...it sums it up pretty well:

https://themustangsource.com/f804/20...-70mph-524388/

 

I agree and would definitely try it myself if I was paying the bill. In my case it was under warranty and I measured the run-out myself so I had my own specs for argument sake with Ford if required.

 

My dealership replaced my driveshaft and the vibration is gone. Thanks Koons Sterling Ford!

 

Awesome! Thank you for the update, 08GOGTCS.

Deysha

 

Hi,

my 2014 GT with AT has the same Vibration. I have now 1350 Km on it and it starts 100km ago. My Vibration makes no noises. I feel it only in the floor, gas Pedal and on the Steering Wheel. I balanced the Tires last Week but the Vibration is not gone. My next step is to rotate the Driveshaft on the rear end but my Problem is, i dont find a marked spot on the flange. Do you fix it ?

 

Just got my car back after 3-days at Ford Service for the vibration, two mechanics, official report, my wheels/tires are the cause. Ugh...

 

I have a similar issue Kn7671,


my post here:
https://themustangsource.com/f804/20...ration-531710/


My dealer turned the drive shaft. Didn't help. They replaced the drive shaft, didn't help.


Ring/pinion rebuild kit is on order but is on back order for 30 days. My rear needs to be re-shimmed they said.


I'm also tempted to go to the after market. I'm tired of waiting for Ford to take responsibility for their issues. They obviously don't prepare well in order to meet their obligations. But what else is new? Every other person/company is the same way.

 

Ford customer service contacted me a few days after I got my car back, and said the dealership logged their official vibration findings on my wheels and tires, which are factory Brembo wheels.

I tried explaining to the Ford Cust Service rep that I created this thread before the car logged 2000 miles, and in that time, I removed and sold the factory wheels/tires, installed my Brembo wheels w/factory Pirelli Tires, even had a set of Ford Racing Boss wheels with new tires, and reinstalled the Brembo wheels with brand new Michelin PS AS3's, and with all combinations of wheels and tires, the vibration has persisted.

The Ford Cust Service rep said they could not change the diagnosis, but that I could take it to another dealership for a second opinion, so I'll be taking my car to my purchasing dealership in the next 1-2 days.

In the time Ford had my car and now, I bought a set of brand new Ford Racing GT500 Forged Aluminum wheels with brand new rear tires as well. Guess what, yes, the vibration still persists.

Now this morning when out for a breakfast run, when accelerating I experienced some new shuddering vibrations. I'm beginning to think my problems are from the transmission or rear end, or maybe a combination of the entire drivetrain, but the problem is worse now more than ever.

 

Decided to get under the car and check out the driveshaft and transmission. My thought was that with this much shudder and vibration, surely I would be able to find something.

Found excessive transmission output shaft to transmission play. Could this be part of the vibration and shuddering?

I've also been also to figure out how to repeat the shuddering. At 40mph, put car in 3rd gear (select shift), and floor it until the car hits 80mph. While the car passes somewhere through 50-75 mph, shuddering is felt, like the driveshaft is going to come out.

 

After 7-days in the shop, they finally tore into the differential to find a problem with the backlash and are going to need to replace the ring gear and pinion. The bad, apparently on national back-order, potentially until September 17th or longer. What can you do?

Here's to hoping that a ring gear and pinion replacement cures the vibration problems.

 

I had the same problem on my /14 v6 with 3.31 axle. My dealer checked u joints, back-lash, pinion angle, tyres and rims. then put a bunch of microphones, sensors and gizzmos on and in the car and "drove" it at speed on a hoist. He told me that it vibrated at a frequency of 81Hrtz (I think it was). He said that the optional axle was prone to do that (why, I don't know (or if it's true)). Ordered vibration dampener from Ford, problem gone. I know it's just a lump of steel (harder to vibrate so it doesn't) but 10lbs means nothing to me. My $.02 Mark

 

@kn7671,


My ring and pinion rebuild kit finally came in. I picked up the car the other day. THe good news is, the decel vibration is gone. This makes me very happy. The bad news is, I have a new moaning noise coming from the passenger side wheel well. It can get REALY LOUD. So now I have to take it back....

 

Got my car back today. Vibration seems to be gone for now.

So far so good. Going to take it easy and drive it like a new car for the first 500-miles. Will report back after a few thousand miles in about a month, or earlier if anything problems crop up.

BTW - Ford had my car 23-days with the back-order on the gears themselves.

 

That's about how long I waited for my ring/pinion kit. Though they gave the car back to me to drive while the parts were on order.


Did they have to replace your limited slip clutch packs as well? Mine were worn ( at 2500 miles ). My rear had to have the gears, clutch packs and all the bearings replaced. They all had damage. No more decel vibration!


It's back at the shop now. I think they found the rear end noise. Also, they might take the trans off and inspect the flywheel and TQ since I have the dreaded ticking noise. I had a previous car that had the same ticking noise and it was solved by simply taking the trans out, the flex plate and the TQ out then putting it all back together. Ticking noise was gone after that. That car got totaled in a car crash. Just hoping they provide the same procedure for this current car since it fixed the last one.

 

A few thousands miles after differential rebuild, the vibration is back to as it was, potentially sometimes worse. I still think the one of the main problems is the transmission output shaft radial (up/down not in/out) play is excessive, as in excess of .100" (1/10th of an inch). If this was a U-Joint or Driveshaft Carrier bearing with over .100" of play, they would be replaced.

While the Ford dealership initially seemed resistent to look deeper into the issue, I'm hoping they will look further into the issue with a little persistence. I was unable to locate any specs for the transmission output shaft radial play, so I looked deeper into the type of bearing used in the trans for the output shaft, Torrington type double needle bearing.

Looking at the radial play specs from various bearing manufacturers for Torrington type needle caged bearings, the maximum radial play spec is no greater than .001", essentially meaning there should be very little movement of the output shaft.

I've asked the Ford dealership to get the official spec from the Ford Techline so we can know where to go from here. I hate to see them try again and again like some other on here to rebuild the rear differential over and over, only to end up in the same place each time.

 

If they missed +/- .050 slop in your output shaft, think you need to find another dealer

Sounds silly, but check your exhaust is lined up. Mine vibrated after i swapped the clutch, all i did was loosen the clamps on the tails and midpipes, shook everything so it wasnt binding, lined up the tips and tightened it back up...

 

They missed it but I did point it out. Since the 2014 Mustang had already ended production when they were working on my car, they could not compare my output shaft play to a brand new 2014 GT with an automatic, so they could only compare it to an F150 (same basic 6R80 transmission) in the shop. They stated the F150 and my car's output shaft play was similar, which may have been, but that only means both were fracked.

I suppose if you drive the car like a little old lady and rarely go over 70 mph, you'll probably never experience the problems I have. Sometimes just getting on and off the throttle causes vibrations now.

While I love cars and driving, I'm seriously hating my car right now. I wante to put the 15" brake kit on the car, but if I can't get this vibration remediated and/or repaired, then I don't think I can tolerate it much long and long enough to make it a worth while upgrade, as I just want to trade it off.

 

I'm going to try the 3rd gear 40 to 80 MPH and see if I get any vibration. My 2011 GT auto vibrated when new and stopped at about 3k and was smooth as silk after I changed tires.