Shaking at 40+ MPH

[Freshmeat]

Okay, so the Town Car is licensed and inspected again... but it has a shake when it's above 40MPH. I mean shake the whole car kind of shake. More pronounced when maintaining speed, but not so much when accelerating or coasting. I thought it was the U-joints. The rear joint seemed tight, but the front was a little loose so I replaced it.

Never really had to diagnose a shake before, so what do I start checking?

[gadget73]

check your tires. if they're old or lumpy, they may vibe even if properly balanced. if they're out of balance, it will vibrate too.

[Freshmeat]

My dad said the same thing. I think I'm going to swap the wheels/tires I used to have on the wagon onto the TC and see if that helps.