Newbie needs help!

[ConfuzdGT]

I bought my first Mustang last week, a '96 GT convertible. The rear tires were worn out so when I felt a vibration above 50mph I figured it was the tires. Bought 4 new tires today and jumped on the interstate. I have a major vibration between 60 and 70. It's there above and below but seems maybe just a little less severe.

Anyone have an idea where to start? I'm now sure it's not the tires and I assume the wheels are OK because they balanced them and should have seen a problem wheel when they balanced them.

 

[fast97gt]

It could not be a vibration at all, last week I thought the same with my 97gt. Come to find out it was a very bad worn shock, it turned out to let the wheels bounce excessivly, but you can also check the u joints. Thated be a good start
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[squeak93]

+1 on checking u joints and drive shaft bolts.

 

[Kilgore Trout]

Most likely tires need balanced. In my experience tire techs are really bad at balancing tires and it often takes going to 2 or even 3 shops to get them balanced properly.

Do your f'n job right the first time tire techs!

Vibration at the speed you mention is almost always tire balance.

Other things it could be:
-wheel bearing
-bent rim
-drive shaft vibration

 

[bhuff30]

I would definately take it back to the shop and ask them to try balancing again. Chances are that it is a tirel balance issue or they'll find a bent wheel.

 

[GDTrumbo]

What tire brand are they? Some brands just suck... Ford (hub centric) wheels or aftermarket? Many aftermarket wheels are just lug centered and that doesn't get it.

Take them back and have the wheels/tires checked for radial/lateral runout.
Watch as this is done if you can. A good balancer operator uses a locator cone on the inside of the wheel, if at all possible, with a rubber faced drum on the front for styled aluminum wheels.

Watch as the wheel is spun and pay close attention to the rim edges and the surface of the tire. I'm sure you'll find something a little off.

GT