Car vibrates when driving

[Dottie L. Simar]

I have a 2005 50th Anniversary T-Bird. The car was running smooth. After an oil change, I noticed that the car was vibrating when driving, expecially on smooth roads. It's like the car is running rough or unbalanced tires. Ford had the car for three weeks trying to find the problem. They cleaned oil on a gasket, change parts in the exhaust system, bolted the engine, etc. The car vibration is better but I still feel it even though it is subtle. I went from Shell Gas 93 octane to BP 93 Octane. It's not bad enough for me to make a big issue about it but it still is there. Can anyone help or is this something I have to live with. Thanks

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[Anezangl]

Dottie, is this your first convertible?

 

[George]

Dottie:
I believe you have what is called "cowl shake". The under pinnings of the new Thunderbirds was from Jaguar's (chassis) which were and not originally built as convertibles. This is more proniounced when the tops are off the car.
If this is your case, there are bolts (eight of them I think) under the car on three cross memebrs that need that need retightening. I believe to 46 foot pounds of torque.
Allow me to do some searching and see if I can come up with some data to bring to the dealer. ---It may take some time and I do have a few appointments today, but be patient.



Another guy said, "when I took my car in for oil change and seat belt recall, just told the service rep to check the bolts on all cross frame bracing. all were "slightly" loose."

 

[George]

Dotie:
If you find it is not cowl shake, another TBird owner had this issue:

"Since I've owned the Bird, there has been a pronounced "body shake" or vibration whenever I go over 70 mph. It seems to shake the most behind the seat--sometimes vibration in the steering wheel.
I've had 3 different wheel balances at different places--different set of wheels--tires checked for flat spots and roundness, etc. I've had the crossbars checked and torqued to 46 ft lbs. Nothing seems to help so far.
A friend of mine at my car club suggested taking it to a place that uses a Hunter Dynamic Balancer. I went to their website and read about their equipment--seems impressive. I contacted their service manager and he recommended using the Hunter GSP 9700 Road Force Measurement System.

He found a Lincoln dealer who had the right eqiuipment and here's the resolution:

"Got it fixed today. Went to a Wheel Specialty House who had the Hunter equipment and very experienced, trained personnel. It took them about 2 hours, but the wheels were out of balance big time (despite what others had told me and after 3 wheel balances). They also had to reset the tires on the rims. The Road Force Measurement System really does a great job. So, for those of you who have vibration problems at higher speeds (not cowl shake), I would go to the Hunter website www.gsp9700.com. It will explain how the sytem works and you can search for the facility nearest you that uses their equipment. Give it a shot--it worked for me! The locator is www.gsp9700.com/pub/search/findgsp9700.cfm "

 

[Dottie L. Simar]

Thanks again George

Thanks George for your quick response. I knew you would be the one to help me if anybody. Yes, this is my first convertible, however, I do not take the hard top off. I consider it as permanent. Please don't think this is weird. I just love the car as it is, that's why I bought it. I will take the time today (during working hours) to read all the threads you sent me. I also forgot to mention that before Ford made the car a lot better, it could feel the vibrating, and still do sublely, in the gas peddle and seats and side of the doors.

 

[George]

Dottie:
You could still have cowl shake with the hardtop on. So, it's certainly worth it to have them check out the 12 bolts on the X-Braces, underneath.

Then, if that doesn't correct your issue my other response was related to tire balancing, but with a Hunter system. So if you're at your dealers, ask if their balancing system is the same Huinter sytem I mentionsed in my post above. If not you can try a Lincoln dealer. They work a lot on TBirds too, since the drive line is all Lincoln LS.
Good Luck!!

 

[Dottie L. Simar]

Thanks George

Thanks George. I will follow up on your recommendations next time I go in for an oil change (two to three weeks) and let you know if they have tried some of your recommendations and if not, would they look at it now. You have a wealth of information. Thanks again.

 

[George]

And, it should be warranty service...

 

[Anezangl]

Hey George, I know on the mazda miatas they make an after market cross brace that bolts up under the hood. It takes only 10 minutes to bolt it up. It attaches at the top of the shock towers and stops the cowl shake dead in its tracks. Do you know of something like this for the birds?

 

[George]

No I do not, and I've had mine for almost 5 years.

Tightening those 12 bolts have done it for about 35 people that I know of, that had that problem. One exception-
There was only one guy who had vibration and it wasn't the x-braces, and his was the wheel balancing that I posted above.
Note: The birds are much larger than the Miata and therefore probably more strain on that LS chassis. In my opinion, the Miata is small enough that it could be corrected as you stated above.
I am not sure if that was a chassis from another car or if it was designed specifically for the Miata.
Have a great day 😎