shaking over 55 mph

[beerboy]

just recently put new cragars on p215 70 14 tires on front and p245 60 15s on the back on my 73 duster, while on the expressway, not often by the way, i get some shake at 50 60 mph. and steering feels like its floating around some, i know these a bodys do not handle like a new vette. any how, you guys think its alingment-- tires on front not balanced correctly-- bad bushings??? bushings are rubber wth afewsmall cracks in the rubber.

 

[TrailBeast]

Could be any of the above, or a combination of them.
Misaligned tires with bad shocks will make a tire hop, as will bad shocks and an out of balance tire.
Or just a bad shock
Or just out of alignment
Or just an out of balance tire.
Or bad bushings causing a misalignment and an out of balance tire/s

See where this is going?
It's kind of an all or nothing type thing.

 

[diymirage]

don't forget the possibility of the drive shaft being out of whack (balance)

 

[TrailBeast]

don't forget the possibility of the drive shaft being out of whack (balance)

I relate a "shake" to be a shudder and a driveline as a vibration.
But there I go assuming.

 

[Bulldozer]

sounds like you have the elusive "death wobble"