I have a 72 coupe that has a bad vibration. The faster i go the less the vibration.
I'm thinking it has something to do with the tires. its like every other rotation is when it vibrates.
any ideas or suggestion would be great.

 

jack the tires up and spin them to see if the tire goes up and down. Even a little bit means the tire is out of round. This is one thing you can eliminate. Does our steering wheel shake??

 

Put it in park and rev the motor up slowly. Does it do it then?

 

Thanks for the reply guys. The steering vibrates alittle and revving in park it dosen't. It vibrates the worst around 45 to 55 mph.

 

Its not a motor mount or a trans mount. I would start looking at you tires. Is you frontend worn out? Is the vibration coming from the back? Could it be mud in your tires?

 

Out of balance drive shaft?

 

Could be, he would have to jack the rearend up and pick it in gear and rev the motor up and see what is going on.

 

The first thing I would do would be to take it to a tire shop and have them check the balance of all four tires. If one of the tires is out of round, they can tell you. Then you just need to replace that tire. If all the tires are balanced, and it continues to do it, I would suspicion the Universal joints. If they have grease zerks in them, you might want to grease the old ones up first before replacing them.

 

Thanks for all the replies. Im taking the stang to a local tire shop in the morning to have all four tires checked and balanced. Also i checked the drive shaft and found a small dent near the rear of the shaft, its not a very big dent about the size of a quarter. Would that throw of the balance of the drive shaft.

 

Depends how it got dented...could have knocked off a weight or bent the shaft a little.
If the tires don't fix it, you may need to have the shaft straightened and/or balanced, but check the u-joints first.