Vibration between 50 & 70 mph

[GT Pony]

My rumble started at ~300 miles. Since then, two ford mechanics have ridden with me on smooth roads. Both were very surprised by the rumble and by how loud it was. The first said it was "just awful". The second said, "what in the world... I've never...".

Yet so far, neither of them have been "authorized" to do anything about it.

It's strange that something like this would start up after some mileage. I'm wondering if it's an isolator bushing or something that goes bad. Someone said the drive shaft is 2-piece on the GTs, if so there has to be a carriage bearing and isolator mid-shaft someplace. Wondering if that goes bad.

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[1stFord]

Well, just got the car back from an extended stay with the dealer and the new driveshaft did nothing for my vibration. I will start talking with them again on Monday to see if there is going to be a next step and I am hoping that the outstanding service that I have received so far continues.

 

[GT Pony]

Dang, new drive shaft and no improvement is disappointing for sure - sorry to hear that. Wondering if it's bad tires? Even though wheels/tires can balance out perfectly, it the tires have internal flaws they can still cause vibration issues. A road force balancing machine is best to use for figuring out if tires are bad or not.

 

[Old Ford Guy]

1stFord...Yuk can imagine that is really disgusting for your long wait and then this result!! My tires were checked on road force and they were just fine so after that went ahead and ordered the DDS DS which seemed to cure 95% of my issue. Do a number of these DS just come out from Ford not balanced properly? Been going to find some shop that balances shafts and just see how my OEM does but have not got around to it. Is there any relationship of the wheel type...mine are the optional forged 18 inch that sort of look like the Magnum 500 of old other than being forged rather than stamped steel. Would not think Ford would tighten wheel bolts improperly so somewhat out of place and then when person takes them off to check balance gets them back on correctly?? I just do not like the looks of that center hanger bearing support and mount with it bolted right to tunnel along side the seats either...now with the one piece DS you have none of that potential for vibration or noise transfer.

 

[1stFord]

They have already pulled an entirely new set of wheels/tires off of another car and it made no difference at all. They also performed a road force balance with similar results. I have the PP wheels on mine. The good news is that I have new radiator fans because mine squeaked when shutting down, new section of exhaust because of a leak, and I have new seatback cushions on order because the coolers were not working properly. They also managed to get my trunk perfectly aligned so at least I am 100% satisfied with the cosmetic side of things. I do have to say that driving my car for the first time in 10 days has been a joyous occasion, even with the vibration.

 

[BV600]

Dealership finally acknowledged something is wrong with my gt. Yesterday I got a call saying they balanced all 4 and that did nothing. Took wheels and tires from another car on the lot put them on my car and vibration was still there. I have a feeling it will be there for awhile

 

[GT Pony]

From everything I'm hearing so far, it sure seems to point to the drive shaft itself. But then there have been instances were a new drive shaft didn't help. What are the chances of getting a bad replacement drive shaft? I guess it could happen.

 

[Old Ford Guy]

GT Pony...Sure would be great for Ford to figure this out! Has anyone else out there put in a custom DS???

 

[Juben]

I've put over 1k miles on my car since they replaced the differential and it seems to still be working.

 

[Old Ford Guy]

Juben...that is great! Did Ford reps or service tell you exactly what was wrong with the differential??? It seems very strange to me that the diff could cause the vibration?? Unless the pinion angle was way off but then that is a mounting problem not a problem of the diff?? I don't get it!

 

[888mustang]

I am a auto tech and had training this week,the instructor was a former FSE for Ford and I asked him about how a diff. could cause a vibration.He explained that if the teeth on ring and pinion dont mesh evenly the whole way around it will bind and release the drive shaft causing a vibration.My car goes in Tuesday for a drive shaft so Im hoping it will cure it. It feels like the drive shaft to me so we shall see. I will post the results Wednesday. Thanks for all the posts,Bill

 

[GT Pony]

^^^ Makes some sense on the differential possibly binding in one spot as it turns. If that was the case, I'm wondering if it could be detected by jacking the rear tires off the ground and turning the wheels with the transmission in neutral. Someone that has the vibration badly might try this and see if they can tell there's a binding spot in the drive train or differential.

 

[Old Ford Guy]

888Mustang....thanks for that perspective! If that is the case there would be numerous filings in the case & oil and it would wipe out rather quickly. A magnet through the fill or drain plug hole would allow one to check it out. Maybe the present drain plug has a magnet on it as have numerous others over time.

 

[BV600]

Got a call to come pick my car up it was fixed. Went to pick it up got a BS stpry on how when they put my wheels on it didnt vibrate anymore. Sure enough I drove a mile down the road and it still does it no change. They had it a total of 6 days

 

[Old Ford Guy]

BV600...that is tough to take after 6 days waiting! What a bunch of losers! Ford has to get this figured out!

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