Vibration between 50 & 70 mph

[Lo Pony]

Maybe. But it's also not normal. And NOT from my Roush exhaust. So dunno what their excuse is for "can't find anything wrong"

Mine resonates through the steering wheel also. It will also vibrate cans or cups in the console holder and buzzes the left side panel behind the driver's seat.

You're right - it sounds like a subwoofer that's set to play a single bass note. It is a first order harmonic that matches the frequency of the driveshaft rotation.

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[amilhazes]

Mine resonates through the steering wheel also. It will also vibrate cans or cups in the console holder and buzzes the left side panel behind the driver's seat.



You're right - it sounds like a subwoofer that's set to play a single bass note. It is a first order harmonic that matches the frequency of the driveshaft rotation.

Thank you this is exactly the same as mine. And it was like that before my exhaust. My keys if I set them in small tray in front of shifter will rattle. Or pennies in cup holder will rattle. That's not normal.

 

[Lo Pony]

Thank you this is exactly the same as mine. And it was like that before my exhaust. My keys if I set them in small tray in front of shifter will rattle. Or pennies in cup holder will rattle. That's not normal.

Of course, it isn't normal ! Again, mismatch in mfg. tolerances and lack of understanding about the problem. This apparently includes the drivetrain engineers and the technicians that are supposed to be able to troubleshoot such things. Basically, if it isn't listed in their knowledge base, they don't know how to fix it.

This gives me an idea. I wonder if they can pull up the old TSB on the 99 cars. Let me do a little checking....

 

[Lo Pony]

OLD TSB for 99-01 IRS COBRA

Attached is a screenshot of my message from 2002 on BON Forums. It refers to the 1999-2003 Cobras and concerns the TSB that was issued at that time to address this problem.

Here is the actual text

=====

VIBRATION:
BlueOvalNews has learned that SVT is aware of a vibration occurring at 65-78 miles per hour. Ford/SVT has determined that the cause of the vibration is a possible drive line imbalance. Ford/SVT might be in the process of issuing several technical bulletins asking Cobra owners to check the following:

STEP ONE (1)

1) Are the tires mounted and balanced properly?

2) Is there any undercoating on the driveshaft?

3) Has the driveshaft been replaced by an aftermarket one?

4) Has the vehicle been lowered or is there a bushing failure?

If none of these problems are the cause, then SVT will be offering another possible solution.

STEP TWO (2)

1) Check the vehicle's driveshaft to verify that there are yellow paint indexing dots. One yellow dot should be on the left side of the driveshaft and another yellow dot on the high side of the companion flange.

2) The next step is to measure the companion flange's runout. The specification is .008" maximum runout. Use a dial indicator to do this procedure.

If the above two steps do not solve the vehicle's vibration, these are the additional solutions that SVT will be recommending:

STEP (3)

1) Have the driveshaft offset serviced.

2) Obtain a matched driveshaft and axle set.

3) Obtain a new vibration dampner.

4) Have the driveshaft indexed to the transmission.

SVT might also issue a bulletin to Cobra owners reminding them of the following:

* Engine performance characteristics are different from previous models and that the suspension is different than other models due to rear IRS versus a live axle.

BlueOvalNews has no information on how Ford/SVT will handle the warranty aspect of the drive line problem; however, it is suggested that owners who have a problem(s) with their 1999 Cobra take it to a local Ford or Lincoln Mercury dealership to document your concerns. Remember to keep copies of all documentation for future reference. You can also print this article and take it to your dealership for additional reference if needed.

I think what was actually meant here (I'm the original poster on BON and now) is that the yellow dot on the DS should match the point of max runout on the flange. Sounds like here they recommend to offset the dots by 90 deg. That ain't right! There were questions about that TSB posting back then, and now. Makes no sense.

 

[GT Pony]

The service tech I check my car in with has read this entire thread.

You are lucky, because him reading this thread may give some extra information and things to check out. For instance, if it was my car and I had a lift I would run the drive train in gear and look for any kind of wobbling of the drive shaft and the transmission and differential mating flanges. Even the slightest axial mis-alignment in all these components can cause undue vibrations. A dial indicator with a magnetic base for a more accurate check if needed. There was someone on here that posted a video of his on the lift with the driveshaft rotating and you could see the wobble going on with the naked eye.

 

[shahram72]

You are lucky, because him reading this thread may give some extra information and things to check out. For instance, if it was my car and I had a lift I would run the drive train in gear and look for any kind of wobbling of the drive shaft and the transmission and differential mating flanges. Even the slightest axial mis-alignment in all these components can cause undue vibrations. A dial indicator with a magnetic base for a more accurate check if needed. There was someone on here that posted a video of his on the lift with the driveshaft rotating and you could see the wobble going on with the naked eye.

That was me. On my V6. It wobbles visibly. Still waiting on my driveshaft to come in. Why do Ford parts take so long? I work for UPS and shipping is like 3 days average.

 

[MikeD1]

That was me. On my V6. It wobbles visibly. Still waiting on my driveshaft to come in. Why do Ford parts take so long? I work for UPS and shipping is like 3 days average.

Must be a supply issue with the V6 versions, for my V8 it came in within 3 days of being ordered both times.

 

[shahram72]

My spare tire took 2 weeks!

 

[amilhazes]

You are lucky, because him reading this thread may give some extra information and things to check out. For instance, if it was my car and I had a lift I would run the drive train in gear and look for any kind of wobbling of the drive shaft and the transmission and differential mating flanges. Even the slightest axial mis-alignment in all these components can cause undue vibrations. A dial indicator with a magnetic base for a more accurate check if needed. There was someone on here that posted a video of his on the lift with the driveshaft rotating and you could see the wobble going on with the naked eye.

Well. Not really. The last two messages I've received stated they can't replicate the issues at the dealership...

 

[majtom94]

And after the technician tells you he agrees, someone in the chain decides that you are BOTH wrong! Acceptable vibration.

 

[Lsumba97]

I wanted to provide a follow-up to my original post. I took into the dealership yesterday at 7am. I thoroughly explained the problem and provided printouts of this thread for reference purposes. I was clear and direct about what the problem was and to the credit of the service rep, he wrote down everything and took everything that I gave him.

At around noon yesterday, they called me to let me know that they found that it was a driveshaft issue and that they emergency ordered a new driveshaft to be delivered today and that I would have my GT back by Friday.

I just received a call from the service rep to let me know that they received the driveshaft early this morning and that it has been installed. He told me that the vibrations are gone and that I can pick my car up this afternoon. This will be AMAZING if, in fact, the issue has been resolved. I guess that I am still nervous about it.

I will be so thankful to get out of the Focus that they gave me as a loaner - the double-clutch in that thing about drives me nuts!! I will post tonight and let you all know the results.

 

[Lo Pony]

I wanted to provide a follow-up to my original post. I took into the dealership yesterday at 7am. I thoroughly explained the problem and provided printouts of this thread for reference purposes. I was clear and direct about what the problem was and to the credit of the service rep, he wrote down everything and took everything that I gave him.

At around noon yesterday, they called me to let me know that they found that it was a driveshaft issue and that they emergency ordered a new driveshaft to be delivered today and that I would have my GT back by Friday.

I just received a call from the service rep to let me know that they received the driveshaft early this morning and that it has been installed. He told me that the vibrations are gone and that I can pick my car up this afternoon. This will be AMAZING if, in fact, the issue has been resolved. I guess that I am still nervous about it.

I will be so thankful to get out of the Focus that they gave me as a loaner - the double-clutch in that thing about drives me nuts!! I will post tonight and let you all know the results.

That will be great if it was such a simple fix for once.

 

[Cobra Jet]

Mine resonates through the steering wheel also. It will also vibrate cans or cups in the console holder and buzzes the left side panel behind the driver's seat.

You're right - it sounds like a subwoofer that's set to play a single bass note. It is a first order harmonic that matches the frequency of the driveshaft rotation.

Your last two sentences are a PERFECT description of the resonance of the vibration to the human ear!!! I couldn't have explained it any better - it's true with regards to the "sound" - because if I had maintained my vehicle at 65mph (prior to the fix), not only was the vibe present, but that actual irritating sound was too.

Lo Pony - awesome tech you're providing in this thread as well, it should also help others with the issue!!

 

[shahram72]

Then why is my driveshaft taking so long? It's been a couple weeks! I need to call them.

 

[Lsumba97]

Update on my 2016 GT ... IT'S FIXED! I picked up the car tonight and anxiously accelerated to the magic 50mph threshold and....nothing! No vibration - it was a huge relief.

I was very pleased with the response that I received from my dealership here in Scottsdale, AZ (AutoNation Ford). Again - I dropped it off Wed 7am and had it back Friday 5pm.

I will say that I am still anxious. I'm afraid that one day that vibe is going to creep back. Perhaps I'm just overly cautious. If it does - I will update this thread.

Thanks again to everyone that added to this thread - I believe that it really helped me to get a very quick response.

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